Post on 25-Jun-2020
INTERNSHIP
neel.cnrs.fr
2018 - 2019
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NÉEL Institute is a major research laboratory in physics, with about 450 members. Its collective strength is expressed in numerous national and international collaborative projects, in open technological platforms of exceptional quality, and by a remarkable level of scientific production. This booklet presents the internship topics offered by NÉEL researchers. These cover a wide range of scientific and technological fields, reflecting the diversity of our teams. Magnetism, quantum fluids, new materials, crystallography and surface science mingle with quantum nanoelectronics, nanomechanics, non-linear and quantum optics, spintronics, etc. Beyond our core expertise in physics of condensed matter, we also work at the interface with chemistry, engineering, astrophysics and biology. In all these fields, our mainly experimental activity benefits from the local presence of many worldclass experts in theoretical, analytical and computational physics. NÉEL Institute fosters a technological expertise that is essential to bring our research projects to the highest level, through often unique house-made or in house designed instruments. We are also actively involved in creating value from our research in the sectors of electronics, energy, health and space. This booklet contains the Master internship offers for the 2018-19 academic year. Most of them are Master 2 projects, offering often the possibility of going on as a PhD student. If you are starting your Master degree, you will also find Master 1 project proposals. Many of the Master 2 topics may also be adapted to Master 1 projects. You are welcome to a virtual visit of NÉEL Institute through this booklet and our website, www.neel.cnrs.fr. Please get in touch with NÉEL researchers and come around for a real visit ! Etienne BUSTARRET Director, NÉEL Institute September 2019
Institut NEEL-CNRS 25, rue des Martyrs – Bâtiment - BP 166 – 38042 Grenoble cedex 9 – France
+33 (0)4 76 88 74 68 +33 (0)4 76 88 12 30
L’Institut Néel est une unité propre du CNRS conventionnée avec l’Université Grenoble Alpes
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L’Institut Néel est un grand laboratoire de recherche en physique avec près de 450 membres. Sa force collective s’exprime dans de nombreuses collaborations internationales et nationales, la présence en son sein de plate-formes technologiques ouvertes aux performances exceptionnelles, et un niveau de production scientifique remarquable. Vous trouverez dans ce recueil les sujets de stage proposés par les chercheurs de l’Institut Néel. Les domaines scientifiques et technologiques sont extraordinairement variés, à l’image des activités de nos équipes. S’y côtoient en effet magnétisme, fluides quantiques, nouveaux matériaux, cristallographie, science des surfaces, nano-électronique quantique, nano-mécanique, optique nonlinéaire et quantique, spintronique… Par delà notre cœur de métier qu’est la physique de la matière condensée, nous travaillons aussi aux interfaces avec la chimie, l’ingénierie et la biologie. Dans tous ces domaines, notre activité principalement expérimentale se développe en lien avec de fortes compétences transversales en physique théorique analytique et numérique. L’Institut Néel développe une expertise technologique au plus niveau, essentielle pour mener à bien de nombreux projets de recherche. Enfin, nous nous impliquons activement dans la valorisation de nos recherches et de nos savoir-faire dans les domaines de l’électronique, de l’énergie, de la santé et aussi les sciences de l’univers. Cette brochure regroupe les offres de stage de Master proposés pour l’année universitaire 2018-2019. Ce sont principalement des stages de Master 2 avec pour la plupart une possibilité de continuation en thèse. Si vous commencez votre master, vous trouverez aussi des propositions de stage de Master 1. De nombreux sujets de Master 2 peuvent aussi être déclinés en sujets de Master 1. Je vous souhaite la bienvenue à l’Institut Néel, au moins virtuellement par cette brochure et au travers de notre site web www.neel.cnrs.fr ! N’hésitez pas à contacter les chercheurs de l’Institut Néel afin de nous rendre visite.
Etienne BUSTARRET Director Institut NEEL September 2019
Institut NEEL-CNRS 25, rue des Martyrs – Bâtiment - BP 166 – 38042 Grenoble cedex 9 – France
+33 (0)4 76 88 74 68 +33 (0)4 76 88 12 30
L’Institut Néel est une unité propre du CNRS conventionnée avec l’Université Grenoble Alpes
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NÉEL INSTITUTE Grenoble
Topic for Master 1 internship – Academic year 2018-2019
Table des matières / Contents
Recycling of end of life NdFeB magnets ................................................................................... 9
Flying qubits using ultrashort single-electron charge pulses ................................................... 10
High temperature superconducting oxychlorides: a light element model for cuprates ............ 11
Nouveaux Supraconducteurs .................................................................................................... 12
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NÉEL INSTITUTE Grenoble
Topic for Master 1 internship – Academic year 2018-2019
Recycling of end of life NdFeB magnets
General Scope:
In the frame of the “Sintermagrec” project, funded by the French National Research Agency (ANR-17-
ASTR-0014-02), your mission will be to develop a new fabrication process of NdFeB magnets from
recycled NdFeB magnets collected in urban mines. In the proposed process, sintered magnets collected
in WEEE (Waste of Electrical and Electronic Equipments) are, first, pulverised into NdFeB powders.
In a second step, the development of non-conventional sintering techniques using the powder opens up
an interesting valorization perspective. Thus, within the framework of the proposed study, attention will
be given to study the influence of the processing parameters on the induced microstructure and on the
final magnetic properties
As part of the team, you will conduct the tests (heat treatments, milling, DRX, microscopy, etc…), exploit
the results, report on the results (both written and oral reports).
Research topic and facilities available
In CNRS/ Néel Institute, you will benefit from the expertise of the TEMA group
(Processing Elaboration Materials Applications, 6 persons) on the development of processes
using intense magnetic fields, on the recycling processes as well as on the synthesis of alloys
in various forms. Facilities available in the group include high superconducting magnets, various processing tools
(induction cold crucible, furnaces, milling facilities, separation tools, etc…) and characterization devices
(laser granulometry, ATD/TGA, microscopy, etc…). All common facilities from Institut Néel available
as well (SEM, magnetic measurements, DRX, etc…)
Possible collaboration and networking: This subject is part of the "Sintermagrec” project, which involves both academic and industrial
contacts.
Required skills:
-Interest in the recycling and the valorization of by-products.
-General curriculum with a specialty in Materials Science.
-Autonomy, initiative and ability to work in a team and to adapt to a collaborative project, which
includes partners from academic research and industry.
-Knowledge in physicochemical processes and/or metallurgy is welcome.
Starting date: Spring 2019
Contact:
Sophie RIVOIRARD, Institut Néel - CNRS
Phone:04 76 88 90 32 e-mail:sophie.rivoirard@neel.cnrs.fr
More information: http://neel.cnrs.fr
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NÉEL INSTITUTE Grenoble
Topic for Master 1 internship – Academic year 2018-2019
Flying qubits using ultrashort single-electron charge pulses
General Scope: Coherent manipulation of single electrons in solid-state devices is attractive for
quantum information purposes because they have a high potential for scalability. Depending on the
system used, the charge or the spin may code binary qubit information. A particular appealing idea is to
use a single flying electron itself as the conveyor of quantum information. Such electronic flying qubits
allow performing quantum operations on qubits while they are being coherently transferred. Information
processing typically takes place in the nodes of the quantum network on locally controlled qubits, but
quantum networking would require flying qubits to exchange information from one location to another.
It is therefore of prime interest to develop ways of transferring information from one node to the other.
The availability of flying qubits would enable the possibility to develop new non-local architectures for
quantum computing with possibly cheaper hardware overhead than e.g. surface codes.
Research topic: The aim of the proposed M2 internship is to develop a flying qubit architecture using
ultra-short single-electron charge pulses. In order to generate such ultra-short electron wave packets,
we will leverage on the progress made on THz photon production and use photon to electron conversion
devices to engineer THz electronic charge pulses that can be used in quantum nanoelectronics.
Fig.1: A flying electron generated above the Fermi Sea and propagating in an electron waveguide.
References:
Hermelin et al., Nature 477, 435 (2011); Bertrand et al, Nature Nanotech. 11 672 (2016)
Dubois et al., Nature 502, 659 (2013); Roussely et al. Nature Com. 9, 2811 (2018)
Possible collaboration and networking: This project is realized in close collaboration with the
nanoelectronics group in Saclay (C. Glattli), the THz laboratory of the Université de Savoie Mont-Blanc
(J.F. Roux & J.L. Coutaz), the theory group of CEA Grenoble (X. Waintal) as well as the Quantum
Metrology group (AIST), Tsukuba, Japan (S. Takada)
Required skills:
The candidate should have a good background in quantum mechanics and solid-state physics.
Starting date: anytime
Contact:
BAUERLE Christopher
Institut Néel – CNRS, Grenoble
e-mail: christopher.bauerle@neel.cnrs.fr
web: http://neel.cnrs.fr
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NÉEL INSTITUTE Grenoble
Topic for Master 1 internship – Academic year 2018-2019
High temperature superconducting oxychlorides: a light element model for cuprates
General Scope:
Cuprates were discovered in 1986 to show superconductivity at the highest temperature at ambient
pressure, a record they still detain (see figure 1), but their phenomenology apparently cannot be grabbed
by present theory, so that they are considered among the main unsolved problems in physics today. In
this context, the discovery of the Na and vacancy doped Ca2CuO2Cl2 oxychloride is very promising
indeed to bridge the gap between theory and experiment since it: lacks high Z atoms; has a simplest
crystalline structure for cuprates, stable at all doping and temperatures; and has a strong 2D character
due to the replacement of apical oxygen with chlorine. Therefore, advanced calculations that incorporate
correlation effects, such as quantum Monte Carlo are easier, but relatively little is known about
Ca2CuO2Cl2 from an experimental point of view. We are now filling this gap by a comprehensive
experimental study covering the whole phase diagram, in particular of the magnon and phonon
dispersion, using advanced approaches based on synchrotron radiations.
Figure 1: Cuprates allows exploiting magnetic
levitation above the liquid Nitrogen temperature,
as shown in the picture (Mai-Linh Doan wikimedia
commons, © Creative commons).
Research topic and facilities available: The internship will focus on the growth and characterisation of single crystal of doped Na doped
Ca2CuO2Cl2 oxychloride, Ca2-xNaxCuO2Cl2 using the large volume press available at the institute (pole
X'Press), their crystalline and crystalline (x-ray diffraction) and superconducting (magnetometry)
characterisation, as well as preparation to adapt the sample for advanced spectroscopic measurements
using synchrotron light.
Possible collaboration and networking: Sample synthesis will be made in collaboration with the group of Prof. I. Yamada (Univ. of Osaka,
Japan).
Required skills:
Background in electronic properties of materials and some basic knowledge of chemistry for material
science.
Starting date: From winter to spring 2019
Contact:
Name: D'ASTUTO Matteo
Institut Néel - CNRS
Phone: (+33)(0)4 76 88 12 84 e-mail: matteo.dastuto@neel.cnrs.fr
More information: http://neel.cnrs.fr
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NÉEL INSTITUTE Grenoble
Topic for Master 1 internship – Academic year 2018-2019
Nouveaux Supraconducteurs
Cadre général : Les supraconducteurs sont des matériaux aux propriétés étonnantes. Ils sont connus
pour permettre de faire léviter un aimant, ou de léviter sur un aimant voire les deux (Cf. figure). Ils sont
aussi le siège de propriétés quantiques à la pointe de la recherche actuelle. Nous avons découvert
récemment deux nouvelles familles de supraconducteurs, une famille que l’on dit non-conventionnelle
car la supraconductivité coexiste avec un état magnétique et une famille qui allie cet état quantique avec
des propriétés de structure étonnante (ultra-dureté, auto-réparation de la surface).
Ce stage a pour objet l’étude de ces nouvelles familles de supraconducteurs par différentes techniques
expérimentales de pointe.
Sujet exact, moyens disponibles : Après la découverte d’un état supraconducteur dans la famille de
supraconducteurs à base de Fe (LaFeSiH composé), l’intérêt de la communauté scientifique se porte sur
les propriétés quantiques de ce système et de toute la famille (variation de la composition par dopage).
L’étudiant(e) entreprendra des études sur les nouveaux composés à pression ambiante et sous pression.
Il/elle étudiera le lien entre supraconductivité et magnétisme ainsi que transformation structurale.
L’autre famille de supraconducteurs aux propriétés structurales étonnantes a été découverte encore plus
récemment. A priori, le mécanisme d’établissement de l’état supraconducteur fait intervenir les phonons.
L’étudiant(e) caractérisera les phonons par différentes techniques optiques et spectroscopie de pointe.
Expériences : cryogénie, haute pression, transport, susceptibilité magnétique, spectroscopies optiques.
Interactions et collaborations éventuelles : Ce stage s’insère dans un projet ANR (coll. Bordeaux,
Caen, différentes équipes à l’Institut Néel dont théorie). Collaboration avec l’université de Paris 13.
Formation / Compétences : Physique de la Matière condensée, curiosité et goût pour les expériences
délicates.
Période envisagée pour le début du stage : mars-mai 2019
Contact : Méasson Marie-aude / Matteo d’Astuto
Institut Néel - CNRS : marie-aude.measson@neel.cnrs.fr / matteo.dastuto@neel.cnrs.fr
Plus d'informations sur : http://neel.cnrs.fr
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NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
Table des matières / Contents Recycling of end of life NdFeB magnets ................................................................................... 9
Flying qubits using ultrashort single-electron charge pulses ................................................... 10
High temperature superconducting oxychlorides: a light element model for cuprates ............ 11
Nouveaux Supraconducteurs .................................................................................................... 12
“Seeing” frustration in two-dimensional molecular lattices .................................................... 17
Glass Nanomechanical Resonators in the Quantum Ground State .......................................... 18
Development of a Demagnetization Stage for Sub-mK cooling .............................................. 19
Spectroscopic study of free, only optically trapped nanorods ................................................. 20
Coupling a single quantum dot to a mechanical oscillator ....................................................... 21
Studying electrical properties of nanowires by in-situ electron holography ............................ 22
Investigating Multiferroïcity in Doubly Ordered Perovskites.................................................. 23
Flying qubits using ultrashort single-electron charge pulses ................................................... 24
Growth and redox reaction at the transition metal monoxide/metal interface ......................... 25
Properties of magnetic tunnel junctions with a spin-filtering layer ......................................... 26
STM/STS studies of two-dimensional semiconductors doped with magnetic atoms. ............. 27
Functionalization of suspended thermoelectric nano-generators ............................................. 28
High temperature superconducting oxychlorides: a light element model for cuprates ............ 29
Epitaxial growth of hybrid nanowires for topological quantum computing ............................ 30
Quantum circuits and the Superconductor-Insulator transition ................................................ 31
Wannier Resonances and Two-Frequency Problems in Three-Terminal Josephson Junctions32
Cavitation at the nanoscale ....................................................................................................... 34
Testing the Classical Nucleation Theory ................................................................................. 35
Guided interactions with rare-earth luminescent centers for quantum information processing
.................................................................................................................................................. 36
Theoretical study of excitations in the magneto-electric RMn2O5 compounds ...................... 37
Elaboration of Ln3+-doped α-La(IO3)3 thin films ..................................................................... 38
DNA Nanostructure programming ........................................................................................... 39
Nano-Neuroelectronics ............................................................................................................. 40
Ultrasensitive force measurements at the Quantum/Classical interface .................................. 41
Turbulence Quantique & Vortex .............................................................................................. 42
Superconducting Higgs mode in Monolayer systems under extreme conditions .................... 43
Search for new high Tc superconducting oxides ..................................................................... 44
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New Superconductors with Iron ............................................................................................... 45
Superconducting quantum devices with topological edge channels ........................................ 46
Localized Cooper-pairs in disordered superconductors ........................................................... 47
Search for new high Tc iron-based superconductors ............................................................... 48
Search for superconductivity under pressure in mono and bi-layer graphene ......................... 49
Degradable organosilica nanoparticles for controlled drug delivery ....................................... 50
Controlled nucleation and growth of molecular nanocrystals for biophotonics and advanced
solid-state NMR ....................................................................................................................... 51
White phosphors for LED lighting prepared by sol-gel method .............................................. 52
Molecular spin devices for quantum processing ...................................................................... 53
Interfacing molecular spins with nanomechanical oscillators in the quantum regime............. 54
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
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“Seeing” frustration in two-dimensional molecular lattices
General Scope: Implementing complexity in lattices of objects is a fascinating goal in physics, holding
promises for the discovery of new states of matter with unique properties. One strategy is the search for
lattices with complex tilings, such as those predicted centuries ago by Archimedes and Kepler.
Strikingly, it is only today that these predictions find practical realizations at the nanometer scale.
Another strategy is to use unit objects having more than a single state on the lattice sites, and whose
mutual interactions prevent them minimizing simultaneously all their pairwise interaction energies. We
then say that the system is frustrated. This frustration is linked to the lattice topology, and can be found
in various systems, such as H2O ice or in certain charge and spin lattice models.
Recently, direct visualisation of frustrated spin lattices has proven to be particularly insightful, revealing
intriguing and exotic phenomena. For example, in micrometer-scaled lattices of magnetic dipoles, we
observed magnetic phases being at the same time liquid and solid [1], and other phases apparently
violating the third law of thermodynamics [2]. Based on these results, we now want to launch a new
research track, and address frustration effects at a much smaller (nanometer) scale and in nonmagnetic
systems. More precisely, we would like to investigate the properties of certain two-dimensional
molecular lattices through their real space imaging (using scanning tunneling microscopy). Molecular
systems present the advantage of being tunable with “turning knobs” that are not accessible in larger-
scale systems: in particular, temperature allows to make them fluctuate, and local electrostatic potentials
applied under the metal tip of the microscope allow us to create point lattice defects at will or to excite
the system locally.
[1] B. Canals et al. Nature Communications vol.7, p.11446 (2016)
[2] Y. Perrin, B. Canals, N. Rougemaille. Nature vol.540,
p.410 (2016)
Research topic and facilities available: The student will
fabricate lattices of C60 buckyballs onto a metal surface. We
expect the formation of triangular lattices (with 1 nm lattice
constant) where each C60 buckyball can have two possible
heights (see figure) due to repulsive interactions between
neighboring molecules. There is a direct analogy between this
C60 lattice and a triangular lattice made of Ising spins coupled
antiferromagnetically (i.e., “up” and “down” spins
preferring to align in opposite directions). The goal of this
project is to image C60 lattices using scanning tunneling
microscopy, and to characterize their “magnetic”
configuration (red / blue arrangement in the figure) based on
frustrated spin models. In a second step, defects will be
intentionally introduced in the lattices to investigate the impact of structural disorder.
Possible collaboration and networking: The work relies on a collaboration between several
researchers at the Néel Institute, experts in the physics of frustrated systems and in the preparation of
atomic and molecular lattices on surfaces. The student will be thus involved in a team work and will
benefit from strong technical support.
Possible extension as a PhD: Yes.
Required skills: Condensed matter physics and / or nanosciences.
Starting date: March, 2019
Contact:
Name: Johann Coraux, Nicolas Rougemaille
E-mail: johann.coraux@neel.cnrs.fr ; nicolas.rougemaille@neel.cnrs.fr
More information: http://neel.cnrs.fr
Triangular lattice of C60 molecules,
with part of the molecules (red) located
higher than the other (blue).
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
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Glass Nanomechanical Resonators in the Quantum Ground State
Context:
Keywords: Quantum engineering, two-level systems, glass
Highly motivated students are sought for an ERC-funded project devoted to identifying the
universal low energy excitations of glass. These excitations, thought to be two level systems (TLSs)
formed by atoms or groups of atoms tunneling between nearly equivalent states, will be probed on the
individual level for the first time. This will allow us to make a microscopic test of the controversial
“tunneling model” of glass.
Objectives and means available:
In order to access individual TLSs, a glass nanomechanical resonator will be cooled to its
quantum ground state around 1 mK. Only a few research groups worldwide have succeeded in
cooling a mechanical resonator to the ground state, and most of them use active cooling schemes in
which only the mechanical mode of interest is cold. In contrast, we will draw on our expertise in ultra-
low temperature measurements to cool the entire mechanical resonator to 1 mK.
Ultimately, we are interested in properties of quantum matter. In particular, the identity of the
TLSs will be investigated by making the first measurements of individual TLSs inside a mechanical
resonator. The quantum state of the resonator will be controlled using a qubit to enable these
measurements. First we will look for a signature of an individual TLS in spectroscopic measurements
of the ground-state glass resonator. Then we will use quantum control of the mechanical resonator to
in turn control and measure the quantum state of the TLS. This will yield information about the TLS
and a test of the “tunneling model” mentioned above.
Figure: Intrinsic tunneling two level systems (TLSs) inside a glass nanomechanical resonator. The mechanical
resonator will be cooled to the quantum ground state to enable measurements of the individual TLSs.
Possible collaborations and networking: This work may involve collaboration and interactions with researchers at the Institut Néel,
elsewhere in Europe and in the United States.
Required profile:
The student should have a strong interest in fundamental research and making challenging
measurements at very low temperatures, as well as a thorough understanding of quantum theory at the
Master’s Degree level.
Ce stage pourra se poursuivre par une thèse financée.
Période envisagée pour le début du stage : Flexible
Contact : Andrew Fefferman
Institut Néel - CNRS : 04.76.88.90.92 andrew.fefferman@neel.cnrs.fr
Plus d'informations sur : http://neel.cnrs.fr/spip.php?rubrique69&lang=fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
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Development of a Demagnetization Stage for Sub-mK cooling
General Scope: The Grenoble Ultra-Low Temperatures group cools
condensed matter samples to sub-mK temperatures to probe fundamental
questions in quantum mechanics. These samples include NEMS
(nanoelectromechanical systems) and quantum fluids. Refrigeration by
Adiabatic Demagnetization of Cu or PrNi5 nuclei is the most common way
to achieve this temperature range [1]. Such a cooler uses a ~10 mK pre-
cooling stage provided by a dilution refrigerator. In the present
development, we plan to use a He free « dry » dilution refrigerator
similarly to previous works [2, 3] but with the goal of providing continuous
cooling below 1 mK, which hasn’t been achieved so far.
As heat switches (HS) are of major importance in the final performance of
the system, a first step will consist in characterizing existing HS and
improving their performance, in particular the thermal contacts.
In parallel, the overall system shall be designed taking into account all the thermal constraints (parasitic
loads, thermal resistances, heat capacities, etc) but also the magnetic field aspects (available space in
the dilution refrigerator, shielding, etc)
Available facilities: The student will be part of the ultra-low temperature group (UBT) of Institut Neel.
For the purpose of the development, 2 dry refrigerators will be used. The first one is a homemade dry
dilution refrigerator presently under re-assembly. The second one is a commercial dry fridge that will
be shared with sicentific experiments.
[1] Andres K and Lounasmaa O V 1982. Progress in Low Temperature Physics, vol 8, ed D F Brewer
(Amsterdam: Elsevier) chapter 4, pp 221–87
[2] G. Batey et al.; New J. Phys. 15, 113034 (2013).
[3] I. Todoshchenko et al.; Review of Scientific Instruments; 85 ; 085106 (2014)
Possible collaboration and networking: For the M2 internship, no specific collaboration is foreseen.
In the frame of a PhD, collaboration with industry and with other low temperature groups in Europe.
Possible extension as a PhD: Yes.
Required skills:
- Ability to work in autonomy
- Good competencies in low temperature physics and, more generally, in condensed
matter physics
- Good skills for experimental work
- English (fluent)
Starting date: Flexible
Contacts : Name : Fefferman Andrew / Triqueneaux Sébastien Institut Néel - CNRS
Phone : +33 (0)4 76 88 90 92 e-mail : andrew.fefferman@neel.cnrs.fr
Phone : +33 (0)4 76 88 12 02 e-mail : sebastien.triqueneaux@neel.cnrs.fr
More information : http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
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Spectroscopic study of free, only optically trapped nanorods
General Scope : Over the last years optical tweezers became a standard tool for non-invasive nano-
manipulation in biology, chemistry, and soft-mater physics. In this context we have developed an
original approach based on the use of optical fiber nano-tips and we demonstrated stable and
reproducible optical trapping of micro- and nanoparticles. One major application of optical tweezers consists in the
characterization of the optical properties of trapped
particles, including emission spectra and optical lifetime
measurements. The possibility to study free, only optically
trapped particles, allows us to reduce significantly any
environmental influence. Moreover our specific tweezers
geometry allows to capture the particle emission in three
orthogonal directions, with sub-micron spatial resolution in
one direction.
Research topic and facilities available: The overall scope
of the internship is to implement to the existing optical
fiber tip tweezers and to run spectroscopic facilities adapted for europium-doped NaYF4 nanorods. The
main features are parallel recording of spectroscopic signals captured by at least two of the three possible
routes of our set-up (trapping fiber, auxiliary fiber for spatial scanning, and microscope objective) and
fluorescence lifetime measurements. Both measurements will be run as a function of the position on the
nanorod. The available equipment includes a spectrometer with a state of the art EM-CCD camera, an
electro-optical modulator, a high speed photodiode and a numerical oscilloscope. In this context europium-doped nanorods are of great interest for their very strong orientation dependent
emission. Moreover, the length and aspect ratio of NaYF4 nanorods can be controlled, thus allowing us
to study rods with lengths from 600 nm to up to 2 µm. Recent results have revealed the paramount
influence of the rod length on the trapping behavior, with short rods trapped within two fiber tips and
long rods with only one fiber tip. The obtained results will be interpreted in close collaboration with the
colleagues elaborating the particles. If available they will be compared to similar results obtained by
confocal microscopy.
Possible collaboration and networking: The internship is part of the ongoing SpecTra project which
is founded by the French National Research Agency (ANR). The work will be done in collaboration
with the LPMC at Ecole Polytechnique for the nanorod elaboration and ICB at Dijon for theoretical
considerations.
Possible extension as a PhD: YES
Required skills: Student should have skills in experimental work and have a background in optics and
nanosciences. She/ he will get insight in the very busy domains of optical trapping and nano-physics. Starting date: free as a function of academic program
Contact: Jochen Fick, Institut Néel - CNRS
Phone: 04 76 88 10 86 e-mail: jochen.fick@neel.cnrs.fr
Nanorod trapping in our optical fiber
nano-tweezers using two fiber tips. The
third tip is used for the particle emission
capture.
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
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Coupling a single quantum dot to a mechanical oscillator
General Scope:
Owing to the recent progress in nanotechnology and in ultra-sensitive motion detection methods,
it becomes now possible to associate quantum systems such as superconducting qubits, spins, atoms or
quantum dots to mechanical oscillators. These hybrid systems can be used as ultra-sensitive motion
sensors to detect magnetic or electric field with unprecedented sensitivity. They can also offer the
perspective of storing quantum information on mechanical degrees of freedom.
A few years ago, we have realized
such an hybrid system made of a vibrating
wire and a semi-conducting quantum
dot1,2,3. The very large coupling between
these two subsystems relies on
mechanical strain (cf figure). The
quantum dot undergoes periodic strain as
the wire oscillates along its fundamental
flexural mode at around 500 kHz. The
alternatively tensile and compressive
strain periodically alters the quantum dot
energy levels and therefore the spectral
position of the photoluminescence lines.
Research topic and facilities available: We want to explore the reverse aspect of this coupling by investigating how the resonant optical
excitation of a single quantum dot affects the motion of the oscillator. The first possibility is to set the
wire in motion by exciting a quantum dot, realizing a nano-engine powered by a single quantum dot4.
This realization will raise issues in the field of quantum thermodynamics, where we have a
strong local theoretical support with the group of A. Auffèves. A second possibility is to measure
non-destructively the quantum dot population via a mechanical read out.
The experiment consists in a microphotoluminescence set-up operating at a temperature of
T=4K, and equipped with nanomechanical detection schemes.
References 1 I. Yeo, et al, Nature Nanotechnology 9, 106 (2014) 2 P.L. de Assis et al, Phys. Rev. Lett. 118, 117401 (2017) 3 D. Tumanov et al, Appl. Phys. Lett. 112, 123102 (2018). 4A. Auffèves et M. Richard, Phys. Rev. A 90, 023818 (2014),
Possible collaboration and networking : J. Claudon, J.M. Gérard, CEA/INAC Grenoble;
A. Auffèves, O. Arcizet, Institut Néel; P.L. de Assis, Campinas, Brazil.
Possible extension to a PhD: Yes
Required skills: This experimental internship will deal with nano optics, nanomechanics and semi-
conductor physics.
Starting date: between January and April 2019
Contact:
Name: Jean-Philippe Poizat
Institut Néel - CNRS
Phone: 04 56 38 71 65 e-mail: jean-philippe.poizat@neel.cnrs.fr
More information: http://neel.cnrs.fr/spip.php?rubrique47
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
22
Studying electrical properties of nanowires by in-situ electron holography
General scope:
Nano-objects such as nanowires (NW) and nanotubes are promising candidates for many device
applications ranging from electronics and optoelectronics to energy conversion and spintronics. To
allow successful device integration, detailed knowledge and ultimately control of the electrical
properties of these nano materials at nm length scales are fundamental.
Research topic and available facilities: The aim of this internship is to contribute to the study of semiconducting nanowires regarding their
electrical properties. Off-axis electron holography is a powerful interferometric method taking place in
a transmission electron microscope which allows retrieving the phase shift of the transmitted electron
wave. As the phase shift is sensitive to the electrostatic potential, the electrical properties of the sample
can be measured at the nanoscale.
We aim to apply this technique to a nanowire containing a p-n junction in combination with in-situ
biasing to obtain a quantitative measurement of the electric potential in the nanowire and to probe the
electrically active doping concentration. The student will work in a larger project were p-n junctions
will be studied in different semiconducting nanowire materials, being germanium, gallium nitride and
indium phosphide. The student will focus on one of these material systems that will be defined at the
start of the internship. The student will have access to a state of the art cleanroom and transmission
electron microscope. We have developed sample fabrication based on nitride membranes to make
suspended and contacted nanowires compatible with electron holography that the student will use.
The student’s work will involve:
- (Assisting with) sample preparation
by cleanroom fabrication techniques
including optical and electron beam
lithography.
- Preliminary electrical experiments to
check the sample quality.
- Performing the electrical part of in-
situ TEM experiments (TEM will be
performed by the supervisors),
treatment, correlation and
interpretation of electrical and
imaging results.
From top to bottom: schematics of the nanowire doping,
hologram, phase image showing doping contrast.
Possible collaboration and networking: The internship will be in collaboration with CEMES Toulouse
(Christophe Gatel). Potential collaborations with Vienna University of Technology and Technical
University of Eindhoven.
Possible extension as a PhD: yes (funded European project)
Required skills:
Interest in solid-state physics, electrical properties and characterization techniques and transmission
electron microscopy.
Starting date: Jan/Feb 2019 or for a longer internship asap.
Contact: den Hertog Martien
Institut Néel - CNRS : tél: 0476881045 mail: martien.den-hertog@neel.cnrs.fr
More information at: http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
23
Investigating Multiferroïcity in Doubly Ordered Perovskites
Keywords: Multiferroic materials, Structure, Magnetism
Context: We study a new class of multi-functional magnets called multiferroïcs,
where magnetism and ferroelectricity are strongly coupled together. For
example, electric polarization may be switched by applied magnetic
fields, and vice-versa. These types of materials, currently at the cutting-
edge of condensed matter research, are likely to form key components in
the development of future technology, for example, in memories and
logic devices [1]. Recently we have investigated a new family of doubly
ordered perovskites with the general formula NaLnTWO6 (Ln:
lanthanide and T: magnetic transition metal) and have found that these
materials were multiferroic by the virtue of a new mechanism, the so-
called “Hybrid Improper Ferroelectricity” [2,3].
Fig. 1 : Magnetic structure of the NaYCoWO6 [4]
Objective and available means:
A proper understanding of the interplay between the various physical
properties of these types of materials relies heavily on the knowledge of
the detailed crystal and magnetic structures. The aim of this Master
internship will be to synthesize new compounds with the doubly ordered
perovskites structure and study their electrical, magnetic and structural
properties. The structural investigation will be carried out using x-ray
diffraction at the laboratory as well as at the nearby large facilities when
needed. (European Synchrotron Radiation Facility and Institut Laüe
Langevin high flux neutron reactor). An extended set of physical,
magnetic and electrical measurement facilities (see for instance fig. 1 and
2) is available at Institut Néel and will be used to characterize the
samples.
Fig. 2: Electric polarization
developed under magnetic
field in NaYCoWO6 [4]
[1] S-W Cheong, M. Mostovoy, Nat. Mater., 6, 2007, 13. [2] P. Zuo, PhD thesis, 2017. [3] P. Zuo, C.V. Colin, H. Klein, P.
Bordet, E. Elkaim, E. Suard and C. Darie, Inorg. Chem. 2017, 56, 8478−8489 [4] P. Zuo, C.V. Colin, H. Klein, in
preparation.
Possible collaboration and networking: The student will be working within the Materials, Radiation and Structure (MRS) team of the Néel
Institute. He/she will collaborate closely with several researchers of the MRS team (experienced
chemists, crystallographers and physicists) and work with the technical staff of the laboratory (for
Physical Characterizations, X-Ray and eventually neutron diffraction).
This Master internship could be extended into a PhD within the same research subject if a
funding source for a PhD thesis is obtained (research project grant or PhD contract awarded by the
Physics Graduate School of Grenoble).
Background and expected skills: The candidate must have a background in condensed matter physics, with good basis in materials
Science and interest for exploratory experimental physics.
Possible period for the beginning of the internship: February 2019
Contact : COLIN Claire (claire.colin@neel.cnrs.fr) Institut Néel - CNRS : tel : 04 76 88 74 14, See
also: http://neel.cnrs.fr/spip.php?rubrique63
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
24
Flying qubits using ultrashort single-electron charge pulses
General Scope: Coherent manipulation of single electrons in solid-state devices is attractive for
quantum information purposes because they have a high potential for scalability. Depending on the
system used, the charge or the spin may code binary qubit information. A particular appealing idea is to
use a single flying electron itself as the conveyor of quantum information. Such electronic flying qubits
allow performing quantum operations on qubits while they are being coherently transferred. Information
processing typically takes place in the nodes of the quantum network on locally controlled qubits, but
quantum networking would require flying qubits to exchange information from one location to another.
It is therefore of prime interest to develop ways of transferring information from one node to the other.
The availability of flying qubits would enable the possibility to develop new non-local architectures for
quantum computing with possibly cheaper hardware overhead than e.g. surface codes.
Research topic: The aim of the proposed M2 internship is to develop a flying qubit architecture using
ultra-short single-electron charge pulses. In order to generate such ultra-short electron wave packets,
we will leverage on the progress made on THz photon production and use photon to electron conversion
devices to engineer THz electronic charge pulses that can be used in quantum nanoelectronics.
Fig.1: A flying electron generated above the Fermi Sea and propagating in an electron waveguide.
References:
Hermelin et al., Nature 477, 435 (2011); Bertrand et al, Nature Nanotech. 11 672 (2016)
Dubois et al., Nature 502, 659 (2013); Roussely et al. Nature Com. 9, 2811 (2018)
Possible collaboration and networking: This project is realized in close collaboration with the
nanoelectronics group in Saclay (C. Glattli), the THz laboratory of the Université de Savoie Mont-Blanc
(J.F. Roux & J.L. Coutaz), the theory group of CEA Grenoble (X. Waintal) as well as the Quantum
Metrology group (AIST), Tsukuba, Japan (S. Takada) PhD fellowship available
Required skills:
The candidate should have a good background in quantum mechanics and solid-state physics.
Starting date: anytime
Contact:
BAUERLE Christopher
Institut Néel – CNRS, Grenoble
e-mail: christopher.bauerle@neel.cnrs.fr
web: http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
25
Growth and redox reaction at the transition metal monoxide/metal
interface
General Scope:
The building of new interfaces between oxides is of mandatory importance for the search of magnetic
and electronic properties at the nanoscale. For a decade, an intense research activity has focused on two
dimensional electron gases forming at such interfaces [Ohtomo, A. & Hwang, H. Y., Nature 427, 423-
426 (2004)]. These electronic states present a wide range of interesting properties including a
modulation of the conductivity by applying a gate voltage, superconductivity, magnetoresistance and
spin polarization. The elaboration of these interfaces requires a layer-by-layer tuning of their structure.
More recently it has been shown that 2D electron systems can be generated more easily, simply by
depositing aluminum on the surface of oxides like SrTiO3 TiO2, etc. [T. C. Rödel et al., Adv. Mater.
28, 1976 (2016)]. In this case Al gives rise to a redox reaction, resulting in an amorphous alumina layer
and oxygen vacancies at the interface acting as an electron doping (see Fig.). This phenomenon seems
to be quite general providing that a metal with low electronegativity is deposited. Our aim is to grow
and characterize interfaces with a well-defined structure (unlike amorphous alumina) by depositing
reactive metals like e.g. magnesium on simple and well defined monoxides surfaces such as CoO(100)
or NiO(100).
Research topic and facilities available: During the internship, samples will be grown by molecular beam epitaxy (MBE) and characterized by
combining low energy electron diffraction (LEED), Auger spectrometry (AES) and scanning tunneling
microscopy (STM). High quality CoO(100) or NiO(100) films will be obtained by reactive metal
deposition in molecular oxygen atmosphere. Mg will be deposited on top in ultra-high-vacuum. The
structure of the interfaces showing the desired epitaxial relationship will be determined using
synchrotron radiation x-ray diffraction (as a function of the beam time allocation). This is an essential
preliminary step to the measurement of their electronic properties. In situ resonant x-ray diffraction will
be also employed, when adapted, to gather the onset of induced electronic state measuring the diffracted
signal change at the transition metal adsorption edge. Such a technique is sensitive to the electronic
properties of sharp interfaces.
Possible extension as a PhD: Yes
Required skills: Solid-State Physics, Nanoscience
Starting date: March 2019
Contacts:Maurizio De Santis,, Phone: 04 76 88 74 13, e-mail: Maurizio.De-Santis@neel.cnrs.fr
Yves Joly, Phone: 04 76 88 74 12; Aude Bailly, Phone: 04 76 88 74 13
Institut Néel - CNRS (Surfaces – Interfaces - Nanostructures Team)
More information: http://neel.cnrs.fr
Schematics of the
mechanism of formation of
a highly doped 2DES in
ZnO (from Rödel et al.,
Phys. Rev. Mat. 2,
051601(R) (2018)
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
26
Properties of magnetic tunnel junctions with a spin-filtering layer
General Scope:
Research topic and facilities available: We have recently grown Fe3O4/MgO/CoFe2O4 multilayers on Ag(100) using reactive molecular beam
epitaxy (MBE). In this system the magnetite layer constitutes the magnetic electrode, while the cobalt
ferrite acts as a spin-filter. The properties of this system depend on the epitaxial relationship with the
Ag substrate. It is known that a compressive strain induce an in plane magnetization in cobalt ferrite. In
our system, this effect need to be investigated in details and systematically as function of the film
thickness.
Fig. 2 LEED pattern recorded at different stages of Fe3O4/MgO/CoFe2O4 /Ag(100) growth, showing a good
epitaxy with the substrate and between each layer (a: Ag; b,c,d: Fe3O4, MgO, and CoFe2O4 surfaces ).
During the internship we will growth CoFe2O4 layers of different thickness and we will measure their
magnetic properties by SQUID magnetometry. Once optimized the properties of the cobalt ferrite
barrier, a complete Fe3O4/MgO/CoFe2O4 /Ag(100) device will be elaborated and its magnetoresistence
will be measured by conductive AFM.
Possible collaboration and networking: Technological groups at Néel Institut.
Possible extension as a PhD: Yes
Required skills: A good background in condensed matter physics
Starting date: March, 2019
Contacts: Maurizio De Santis, Phone:04 76 88 74 13, e-mail: Maurizio.De-Santis@Neel.CNRS.Fr;
Farid Fettar, Phone:04 76 88 74 11 42; Jean-Marc Tonnerres, 04 76 88 74 15.
SIN Team (Surfaces – Interfaces - Nanostructures Team) Institut Néel - CNRS
More information : http://neel.cnrs.fr
Spin based electronics take advantage of both the
electron charge and spin in solid-state systems. A
crucial component in applications is the magnetic
tunnel junction (MTJ), where two magnetic layers
sandwich a non-magnetic one. Its conductance
depend on the relative spin orientation of the two
electrodes. An alternative way for generating spin-
polarized currents is based on MTJ with magnetic
barrier materials, which results in spin dependent
tunneling probabilities (Fig. 1). Efficient spin-
filtering has been demonstrated for ferromagnetic
insulators such as EuS and EuO, which show low
transition temperatures. Spinel ferrites like CoFe2O4
are promising candidates for room-temperature spin
filtering.
Fig. 1 Schema of spin filtering (J S
Moodera et al.,J. Phys.: Condens. Matter
19 (2007) 165202
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
27
STM/STS studies of two-dimensional semiconductors doped with magnetic
atoms.
General Scope:
In the monolayer limit, two dimensional (2D) transition metal dichalcogenides (TMDC: 1H-MX2, with
M=Mo, W and X=S, Se) are semiconductors with a direct electronic gap and degenerate valleys (and
opposite spins) at the K/-K corners of the Brillouin zone. This peculiar electronic structure opens
exciting possibilities for information processing that exploit the quantum degree of freedom known as
the valley index. This is « valleytronics ». Indeed, K/-K valleys can be selectively addressed e.g. by
using circularly polarized light. However, for practical uses of these materials in valleytronics, a means
to lift permanently the valley degeneracy is required. One promising route to reach this objective is to
incorporate substitutional magnetic atoms in the TMDC materials during growth.
Research topic and facilities available: The aim of the internship is to investigate by means of scanning tunneling microscopy and
spectroscopy (STM/STS) at low temperature in ultra-high vacuum the atomic and electronic structure
of magnetically doped TMDC layers. The main point will be to analyse the distribution of the
substitutional (magnetic) atoms in the material and to determine whether they induce localized states
and doping. As a probe with “atomic” scale resolution, STM is well suited for such studies. The data
will be compared to ab-initio calculations performed in the Néel Institute. The experimental setup is
available and we have already performed the characterization of the undoped phases (see figure 1).
Figure 1 : a) 60x60 nm² STM image of a monolayer MoSe2 flake on graphene. b) STS spectrum showing
the band edges of monolayer MoSe2 in a defect-free area.
Possible collaboration and networking: This program is developed in collaboration with groups in INAC/Spintec and Institut Néel, which
prepares the samples by molecular beam epitaxy. It is part of an ANR project funded for the period
2019-2022. It inserts in a larger program that aims at developing activity on TMDC in Grenoble
Possible extension as a PhD: Yes
Required skills: Good background in solid state physics (electronic structure of solids).
Starting date: 2019
Contact:
Name: Jean-Yves Veuillen
Institut Néel - CNRS
Phone: 04 76 88 74 61 e-mail: jean-yves.veuilllen@neel.cnrs.fr
More information : http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
28
Functionalization of suspended thermoelectric nano-generators
General Scope:
With the emergence of Industry 4.0, the possibility for wireless sensors to harvest small
quantities of energy (100 µW – 1 mW) in their environment for becoming autonomous is
attracting a lot of attention from both the scientific community and the economic world. Among
different sources of energy, thermal energy presents the
advantage to be available almost everywhere but in
small quantities. To adress the challenge of thermal
energy harvesting, we have developed a planar
thermoelectric generator. It is made of suspended
membranes which are very sensitive to small
intermittent temperature gradient thank to their very low
mass.
Research topic and facilities available:
The expertise developed at the Institut Néel in the
development of suspended sensors dedicated to thermal
measurements at very low temperatures has been used
to design a suspended thermoelectric nano-generator.
The duplication of this thermoelectric nano-module
thanks to standard clean room techniques enabled us to
power sensors and to transmit the information using low
power wireleess protocol (see figure 1).
The main goal of the internship would be to use the
suspended membranes as a support for the deposition
of an active thin film giving to the device another
features. It could magnetic materials for sensing
magnetic fields variation and/or phase change material
(PCM) for stocking energy and rereleasing it when the
temperature of the device is going down a given value.
Possible collaboration and networking:
A start-up exploiting these patents is going to be created. Today, three companies (SNCF, Air
Liquide and Schneider Electric) are working with us for applications of the energy harvesting
system. The team is involved in French and European network of thermal engineering.
Possible extension as a PhD: The internship could be followed by a PhD
Required skills: A Master level in applied physics is required.
Starting date: Spring 2019
Contact:
Name: Dimitri Tainoff
Institut Néel - CNRS
Phone: 04 76 88 12 17 e-mail: Dimitri.tainoff@neel.cnrs.fr
More information : http://neel.cnrs.fr
Figure 1 : SEM image of an individual micro-thermogenerator. The membrane is suspended and a functional material having phase transition will be deposited at its center to reach new properties. The micro-generator are then duplicated and integrated into small prototypes built in the frame of collaboration with industrial partners.
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
29
High temperature superconducting oxychlorides: a light element model for
cuprates
General Scope:
Cuprates were discovered in 1986 to show superconductivity at the highest temperature at ambient
pressure, a record they still detain (see figure), but their phenomenology apparently cannot be grabbed
by present theory, so that they are considered among the main unsolved problems in physics today. In
this context, the discovery of the Na and vacancy doped Ca2CuO2Cl2 oxychloride is very promising
indeed to bridge the gap between theory and experiment since it: lacks high Z atoms; has a simplest
crystalline structure for cuprates, stable at all doping and temperatures; and has a strong 2D character
due to the replacement of apical oxygen with chlorine. Therefore, advanced calculations that incorporate
correlation effects, such as quantum Monte Carlo are easier, but relatively little is known about
Ca2CuO2Cl2 from an experimental point of view. We are now filling this gap by a comprehensive
experimental study covering the whole phase diagram, in particular of the magnon and phonon
dispersion, using advanced approaches based on synchrotron radiations.
Figure 1: Cuprates allows exploiting magnetic
levitation above the liquid Nitrogen temperature,
as shown in the picture (Mai-Linh Doan wikimedia
commons, © Creative commons).
Research topic and facilities available: Most of experiment will be planned at synchrotron facilities in europe and around the world, mainly at
ESRF (Grenoble) and SOLEIL (Paris region), but also at NSLS-II (Brookhaven, US), Spring-8 (Japan)
as well as other facilities depending on available techniques, in order to unveil their electronic properties
at a microscopic level.
Preparation of these experiments will require special care, as the materials are sensitive to air, so that a
special glove box is under installation at the Néel institute, and we will use its facility to growth (large
volume press), crystalline (x-ray diffraction) and superconducting (magnetometry) characterisation.
Possible collaboration and networking: Interpretation of the results will be made with group performing ab-initio electronic structure calculation
including correlation effects in Paris (Ecole Polytechnique) and USA (University of Illinois). Sample
synthesis will be made in collaboration with the group of Prof. I. Yamada (Univ. of Osaka, Japan). Part
of the synchrotron spectroscopy studies will be performed in collaboration with M. Dean (Brookhaven
National Laboratory).
Possible extension as a PhD: Yes, this project is part of a PhD program, of which this Master Internship could be a first approach.
Required skills:
A good background in electronic properties of material, with the will to have a global approach, from
material synthesis and characterisation to advanced spectroscopic properties. Team work will be an
essential part of the project success.
Starting date: Winter 2019
Contact:
Name: D'ASTUTO Matteo
Institut Néel - CNRS
Phone: (+33)(0)4 76 88 12 84 e-mail: matteo.dastuto@neel.cnrs.fr
More information: http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
30
Epitaxial growth of hybrid nanowires for topological quantum computing
General Scope:
One interesting and promising proposal for quantum computation relies on the so called topological
protected quantum bits. Realizing such quantum bits depends on the ability to make materials that can
host Majorana bound states. In 2012, signatures of such states were reported in one-dimensional
semiconductors with high spin-orbit coupling, coupled to a superconductor. Since then, nanostructured
hybrid materials based on superconductor/semiconductor interfaces have received increased attention.
Yet, controlled formation of topological protected states can only be realized if the
superconductor/semiconductor interface is of high quality. Creating those interfaces in an epitaxial
fashion would have many advantages, among them better transparency, controlled interface chemistry,
higher current injection and lower disorder.
Combining crystalline metals and semiconductors is challenging because of the fundamental different
properties of both families of materials. In-situ epitaxial growth of InAs/Al and InAs/Nb core-shell
nanowires were recently developed. The InAs/Al nanowire devices revealed a superconducting hard
gap, demonstrating the high potential of in-situ shell epitaxy. Such structures are currently studied at
Microsoft Station Q to build a topological quantum computer. In our project, we propose to develop
novel hybrid interfaces using vanadium and tantalum grown epitaxially on InAs. These novel
combinations of materials have strong potential not only to understand crystal growth but also to reach
the Majorana regime and perform further topological experiments thanks to the higher critical field of
V and Ta in comparison with Al.
Research topic and facilities available: In this project, the student will carry out the growth of inclined hybrid nanowires in a III-V molecular
beam epitaxy reactor. She/he will focus on InAs/V and InAs/Ta core/shell nanowire fabricated using
templates developed in the cleanroom. The student will perform the characterization of the samples by
SEM and EDX. Together with partner labs, she/he will participate in low temperature measurement
campaigns using a dilution fridge to probe the superconductivity induced in the InAs nanowires.
Moreover, high-end structural characterizations (TEM, XRD) will be performed on the hybrid
nanowires to unravel the growth mechanisms at the superconductor/semiconductor interface.
Collaboration and networking: University of Pittsburgh (S. Frolov)
University of California in Santa Barbara
(C. Palmstrom)
CEA-INAC (J. Meyer, M. Houzet, F. Lefloch)
Possible extension as a PhD: Yes (funding from ANR PIRE HYBRID)
Required skills:
Motivated experimentalist
Programming (Python)
Starting date: march 2019
Contact:
Name: Moïra Hocevar
Institut Néel - CNRS Phone: 04 78 38 35 13
e-mail: moira.hocevar@neel.cnrs.fr
More information: https://pirehybrid.org
(a) (b)
(c)
(a) InAs nanowires will be grown by the VLS mechanism using
gold catalysts. Then a shell will be fabricated by switching the
growth mode to 2D growth. (b) SEM image of a sample of
inclined InAs nanowires. (c) SEM image of a core-shell nanowire
device.
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
31
Quantum circuits and the Superconductor-Insulator transition
General Scope: During the last decade, it has been demonstrated that superconducting circuits
embedding Josephson junctions behave as quantum bits or qubits. These circuits appear as artificial
atoms whose properties are defined by their electronic characteristics (capacitance, inductance and
tunnel barrier). As of today, they are considered as one of the most promising platform to perform
quantum computation.
On the other hand, understanding the details of the Superconductor-Inductor phase transition remains
one the most challenging problem in condensed matter physics since it merges various ingredients such
as interactions, mesoscopic superconductivity or disorder.
This project aims at using the tools developed for superconducting qubits to gain new insights on the
Superconductor-Insulator transition and more specifically on one of the most intriguing and promising
disordered superconductor: Indium Oxyde (InOx) [1]. It builds on the expertise of two teams at the Néel
Institute: the quantum coherence team (supervisor: Nicolas Roch) and the quantum nanoelectronics and
spectroscopy team (supervisor: Benjamin Sacépé).
During a very recent effort to bridge these two fields of research, we already obtained very exciting
preliminary results using a very long microwave InOx resonator (see figure and [2]).
[1] Low-temperature anomaly in disordered superconductors near Bc2 as a vortex-glass property,
B. Sacépé et al. arxiv:1609.07105, Nature Physics (2018) in press
[2] Probing light-matter interaction in the manybody regime of superconducting quantum circuits, Javier
Puertas-Martinez, PhD Thesis, Grenoble Alpes University (2018).
Research topic and facilities available: Both teams have a strong experience in nanofabrication and
cryogenic equipment. The quantum coherence team specializes in the coherent control and manipulation
of superconducting qubits while the quantum nanoelectronics and spectroscopy team is internationally
renowned for its expertise on InOx. The student will use state-of-the-art setups combining very low
temperatures (around 10 mK), quantum-limited microwave detection chains and high-magnetic fields
(up to 15 T) to study. The devices are fabricated in the clean room of the Neel Institute (Nanofab). If the
candidate is interested in learning these fabrication techniques, she/he can be associated to this part of
the project as well.
This internship can be pursued toward a PhD
Required skills: Master 2 or Engineering degree. We are seeking motivated students who want to take
part to a state of the art experiment and put some efforts in the theoretical understanding of the
Superconductor Insulator transition.
Starting date: Flexible
Contacts: ROCH Nicolas (nicolas.roch@neel.cnrs.fr ) website : http://perso.neel.cnrs.fr/nicolas.roch
SACEPE Benjamin (benjamin.sacepe@neel.cnrs.fr ) website: http://sacepe-quest.neel.cnrs.fr/
Measured InOx resonator. (a) Circuit
diagram of the sample. It consists of a
transmission line of impedance Z and
propagation constant k coupled via
capacitances Cc to input and output 50 Ω
ports. (b) Optical image of the sample
showing one of the coupling capacitors
and one 50 Ω pad. The pads are made of
gold. The substrate is silicon. (c) SEM
image of the InOx wire. It corresponds to
the blue square in (b).
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
32
Wannier Resonances and Two-Frequency Problems in Three-Terminal
Josephson Junctions
Introduction : Since the beginning of the
1960s, the Josephson effect has focused interest of
the condensed matter physics community. It lead to
major applications in the field of quantum
information and technologies. The Josephson
effect appears when two superconductors are
connected by a non-superconducting material, and
the underlying mechanism is related to the
formation of Andreev bound states. These Andreev
doublets produced by the proximity effect appear
in the gap, and they are sensitive to the
superconducting phase. The Andreev bound states
can be seen as two-level systems, and they are due
microscopically to the formation of pairs of
entangled electrons in the normal conductor. Many
properties of the Josephson effect, such as the
value of the current, depend on the energy-phase
relation of the Andreev bound states at zero bias
voltage. A deep analogy appears between band theory in solid state physics and Josephson junctions. For
instance, the superconducting phase between 0 and 2 π plays the role of the wave-vector in the first
Brillouin zone. On the other hand, the acceleration of the electronic wave-vector due to an electric field
(which leads to Bloch oscillations [Zener1934]) is similar to the Josephson relation for the time
evolution of the superconducting phase variable. Josephson junctions are thus expected to produce
effects similar to those of solid state physic, like spectral properties [Wannier1960] of Bloch oscillations
[Zener1934], or topology-related effects. Context : Our goal since several years has been to determine the fate of the equilibrium Andreev
bound states in the presence of bias voltage. We have developed recently [Mélin2017] numerical and
analytical calculations for three-terminal superconductor – quantum point contact – superconductor
junctions (see figure above). We have developed an analogy between the nonequilibrium dc Josephson
effect and notions from band theory. The nonequilibrium Andreev bound states look like “ladders of
Wannier-Stark resonances” in semi-conducting superlattices [Wannier1960], which were observed by
optical spectroscopy in the end of the 1980s [Mendez1988]. We have discovered two new effects on the basis of numerical calculations for a time-periodic
Hamiltonian: correlations between Cooper pairs [Freyn2011] which were already demonstrated
experimentally [Cohen2017]. Second, Wannier-Stark ladders [Mélin2017] are the subject of an on-
going experimental work in the group of Romain Danneau in Karlsruhe. Methods more general than
those relying on time periodicity will have to be developed in order to address two-frequency problem,
for instance to sweep the Brillouin zone associated to superconducting phases in order to calculate a
Chern number [Riwar2016]. The PhD thesis project aims at exploring such problems with two
independent frequencies, which can be in a commensurate or incommensurate ratio. Work program for the internship : A simpler problem will be proposed for the internship, so
that the student can become acquainted with recursive Green’s functions, in connection with an on-
going experiment in Grenoble on the role of nonequilibrium quasiparticle populations injected by the
tip of a scanning probe microscope in a two-terminal Josephson junction. Results on this problem are
expected within a short period of time.
A three-terminal Josephson junction, in which a
quantum point contact x is connected to three
superconductors.
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
33
Work program for the PhD thesis : The first project of the PhD thesis will be to justify the Markovian
approximation by testing it against numerically exact calculations that we master well [Mélin2017].
Once the method will have been tested, it will be proposed to couple a two or three-terminal Josephson
junction to ac voltages, in order to excite transitions between Wannier-Stark levels belonging to different
sub-bands. Two approaches will be developed: calculations based on the density matrix in the
Markovian approximation which will be compared to the rotating wave approximation. These
calculations will pave the way to NMR-type manipulations of a Floquet two-level system.
It will be also proposed to calculate the finite frequency noise spectrum, in connection with the
experiments in Romain Danneau’s group at the Karlsruhe Institute of Technology in the framework of
a Grenoble-Karlsruhe international laboratory The goal of these experiments is to provide evidence for
Floquet-Wannier-Stark ladders. Finally, as mentionned above, it will be proposed to address a two-frequency problem, allowing
for sweeping the Brillouin zone of the two relevant phase variables in the presence of two slightly
different bias voltages Va and Vb in an incommensurate ratio. This type of problem with a “slow” and a
“fast” frequency was treated with micro-local analysis in the mathematical community, and it was used
in Grenoble in order to calculate the bottom of the Hofstadter spectrum for a network of superconducting
wires (Wilkinson-Rammal approach, in connection with Pannetier’s experiments [Wang1987]). It will
be proposed to develop these calculations in close collaboration with Frédéric Faure and Alain Joye at
Institut Fourier in the mathematics department of Grenoble-Alpes University. It will also be proposed
to tackle this question in the framework of the Markovian approximation. In particular, special care will
be devoted to the fate of topology in the presence of relaxation, in connection with heat flows. Environment of the projects : This project is within a long-standing collaboration between
Régis Mélin et Benoît Douçot. Numerical calculations will be carried out on the Rouen platform
(CRIANN) through a collaboration with Jean-Guy Caputo (applied mathematics at INSA-Rouen). A
French-German ANR international project was proposed with Romain Danneau, who fabricates devices
based on bilayer graphene, and realizes finite frequency noise measurement of Josephson junctions.
Finally, a collaboration has started with Frédéric Faure and Alain Joye in the mathematics department
of the Grenoble-Alpes University, with regular meeting on a monthly basis.
Advisor : Régis Mélin, Institut Néel, Grenoble
Co-Advisor : Benoît Douçot, Laboratoire de Physique Théorique et des Hautes Energies, Paris
Possible extension as a PhD: The internship could be followed by a PhD Required skills: The candidate should be familiar with advanced quantum mechanics Starting date: Spring 2019 Contact: Régis Mélin, CNRS, Institut Néel Grenoble, Phone number: +33-4-76-88-11-88 E-mail address: regis.melin@neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
34
Cavitation at the nanoscale
Keywords: statistical physics, porous materials, helium, low temperature, optics
General Scope:
Cavitation, i.e. the formation of a vapor bubble in a stretched liquid, is of fundamental interest. For
decades, the consensus has been that, in bulk liquid, cavitation occurs via the stochastic formation of a
bubble nucleus as described by the classical nucleation theory. We want to elucidate whether this also
holds for liquids confined at the nanoscale.
Research topic and facilities available: Cavitation takes place when liquids are in a metastable state below their saturated vapor pressure. It is
possible to reach this state through active techniques such as ultrasonic waves or intense mechanical
stirring. Alternately, natural evaporation in trees drives their sap to large negative pressures, eventually
triggering adverse cavitation. This has inspired a different route to study cavitation, namely the
‘synthetic tree’ concept: the idea is to have liquid inside a cavity connected to a vapor reservoir through
a narrow neck also filled with liquid. When pressure in the vapor reservoir is reduced, the liquid inside
the cavity is forced to large negative pressures, allowing to observe cavitation (see fig a).
Using fabrication techniques (coll. L. Cagnon), we have obtained this geometry with alumina
membranes (fig b) where cavities have nanometric sizes. They are made out of individual cylindrical
pores, where they self-assemble in hexagonal arrays (fig c, SEM top view). The cavities are defined by
changing the diameter of the pores during the growth process (fig d, SEM side view). The first results show
that conventional fluids indeed cavitate inside these samples. The task of this intership will be to
elucidate whether cavitation can also be observed with liquid helium. This preliminary step opens the
way to a thesis studying the dependence of cavitation on the cavity size.
The team
Our team (2 permanents + 1 postdoc) works at the crossroads of low temperature and statistical physics,
focusing on porous materials. We use an original approach where the fluid of interest is helium, taking
advantage of its unique properties as compared to other fluids.
Possible collaboration and networking: This work is part of the project CAVCONF supported by ANR. In this framework, the PhD student will
participate to experiments using complementary techniques and fluids at Ecole Normale Supérieure
(LPS-ENS, Paris) and Université Pierre et Marie Curie (INSP, Paris).
Possible extension as a PhD: yes Required skills: the candidate should have a background in condensed matters physics
Starting date: flexible to the trainee academic program
Contact: Panayotis Spathis / Pierre-Etienne Wolf panayotis.spathis@neel.cnrs.fr / pierre-etienne.wolf@neel.cnrs.fr For more information:
- on the ‘artificial tree’ concept @ Cornell: http://www.stroockgroup.org/home/research
- on the fabrication process: http://neel.cnrs.fr/spip.php?article2056&lang=fr
- on the team: http://neel.cnrs.fr/spip.php?rubrique162 or better: drop by the lab!
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
35
Testing the Classical Nucleation Theory
Keywords: statistical physics, porous materials, nanofabrication techniques General Scope:
Cavitation, i.e. the formation of a vapor bubble in a stretched liquid, is of fundamental interest. For
decades, the consensus has been that its occurrence is correctly described by the Classical Nucleation
Theory (CNT). However, very few experimental studies are in quantitative agreement with this theory.
Our goal is to test its accuracy through benchmark cavitation experiments. Research topic and facilities available: Cavitation takes place when liquids are in a metastable state below their saturated vapor pressure. It is
possible to reach this state through active techniques such as ultrasonic waves or intense mechanical
stirring. Alternately, natural evaporation in trees drives their sap to large negative pressures, eventually
triggering adverse cavitation (see a simplified view fig a). This has inspired a different route to study
cavitation, namely the ‘synthetic tree’ concept: the idea is to have bulk liquid connected to a vapor
reservoir through a porous structure also filled with liquid. When pressure in the vapor reservoir is
reduced, nanometric menisci develop in the porous structure, forcing the liquid to large negative
pressures for which cavitation can occur (see fig b).
The task of this internship will be to design and build the first samples using nanofabrication techniques.
Porous silicon membranes will be synthesized and then bonded on patterned glass substrates. The
behavior of fluids condensed inside these samples will then be studied to measure their equation of state
at negative pressure. Subsequently, the occurrence of cavitation will be monitored with optical
techniques and compared to the predictions of the CNT.
The team
Our team (2 permanents + 1 postdoc) works at the crossroads of low temperature and statistical physics,
focusing on porous materials. We use an original approach where the fluid of interest is helium, taking
advantage of its unique properties as compared to other fluids.
Possible collaboration and networking: This work is part of the project CAVCONF supported by ANR. In this framework, part of the fabrication
will be done at Université Pierre et Marie Curie (INSP) and some measurements at Ecole Normale
Supérieure (LPS-ENS, Paris).
Possible extension as a PhD: yes Required skills: the candidate should have a background in condensed matter physics, with a focus on
nanosciences.
Starting date: flexible to the trainee academic program
Contact: Panayotis Spathis / Pierre-Etienne Wolf panayotis.spathis@neel.cnrs.fr / pierre-etienne.wolf@neel.cnrs.fr For more information:
- on the ‘artificial tree’ concept @ Cornell: http://www.stroockgroup.org/home/research
- a review on porous silicon : http://www.mdpi.com/1996-1944/3/2/943
- on the team: http://neel.cnrs.fr/spip.php?rubrique162 or better: drop by the lab!
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
36
Guided interactions with rare-earth luminescent centers for quantum
information processing
General Scope: Rare-earth ions because of their unique 4f electronic configuration form well isolated systems when
embedded in solids. They have long coherence time at low temperature making them highly promising
qubits for the development of quantum technologies. Their well-known optical transitions, historically
exploited for lasers, can be now used as a support for optical quantum memories and more generally as
a fast and versatile element of control on the qubit. High quality optical crystals containing rare-earth as
low concentration impurities can be obtained routinely. The qubit manipulation using both optical and
radio-frequency excitations is directly performed on millimeter-size bulk with a going through laser
beam and proximity electrodes RF coupling (see figure). Higher integration is desired not only to
improve the readiness level of quantum technologies but also to obtain a stronger optical and RF
coupling leading to a faster operation time.
Research topic and facilities available: In this project, we propose to investigate experimentally a new platform for rare-earth based quantum
processing by considering epitaxial semiconductors as host matrices instead of bulk oxides (see figure).
The growth and fabrication of III-V semiconductors inheriting from years of development in electronics
allow to access micro- and nano-size samples. Bulk devices can now be compacted by three orders of
magnitude allowing a stronger (optical and RF) fields confinement and a much faster qubit control as a
consequence. At the start of the project and depending on the expectation of the candidate, the internship can be
oriented toward the growth/fabrication and/or the design of the optical setup using commercial templates
as a testbed. Both aspects are very demanding in terms of technical skills with epitaxial material
engineering on one side and optical design in low temperature environment on the other side.
Possible collaboration and networking: M. Hocevar, M. Urdampilleta (Institut Néel), B. Daudin
CEA/INAC, A. Bartasyte (FEMTO-ST, Besançon) Possible extension as a PhD: Yes Required skills: Experimental including optics, materials science and engineering, nanofabrication. Starting date: between January and April 2019 Contact: Name: Thierry Chanelière Institut Néel - CNRS Phone: e-mail: thierry.chaneliere@neel.cnrs.fr
Bulk oxides doped with rare-earth ions can be advantageously
replaced by semiconductor doped matrices to shrink the device to
micro-size scale and then benefiting from a strong optical and RF
field confinements for qubit addressing.
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
37
Theoretical study of excitations in the magneto-electric RMn2O5
compounds
General Scope: Multiferroic materials are multifunctional systems that couple multiple orders and in
particular magnetism and ferroelectricity. Their interest is double. First the possibility to control
magnetism with an electric field has many potential applications in the domains of energy saving in
microelectronics or for data storage and processing. Second, the properties of these systems raise a large
number of fundamental questions. For instance, the origin or the amplitude of the magneto-electric
coupling remains to be fully understood. The complexity arises from the numerous degrees of freedom
involved that are all intrinsically interdependent. One can cite for the static aspects the structural (atomic
organisation), magnetic (spins amplitude and orientation) and dielectric (spatial distribution of charges)
parameters, while phonons and magnons may also be coupled in excited states.
Research topic and facilities available: In this internship proposal, we propose to investigate the
properties of a particular family of magneto-electric multiferroics : the RMn2O5 (R=Rare Earth).
Studying these materials is motivated by their very strong magneto-electric coupling (a field of only 2
Tesla can reverse the polarization [1]) and by the microscopic mechanism which is at work in this case
(exchange-striction)[2,3,4].
Fig.: Polarisation reversal using a magnetic field
in TbMn2O5
[1] N. Hur et al, Nature 429, 392 (2004) [2] G. R. Blake, et al, Phys. Rev. B 71, 214402 (2005) [3] G. Yahia … M.-B. Lepetit et al, Phys. Rev. B 95,
184112 (2017) [4] G. Yahia … M.-B. Lepetit et al, Phys. Rev. B 97,
085128 (2018)
For this purpose the student will perform ab-initio calculations, learn how to map them into Fermi level
effective models and to solve the latter to compare with experimental results. She/he will thus
learn the basis of electronic and magnetic struture calculations
learn how to use the supercomputers accessible in the national/regional computation centers
learn how to extract the important information from the calculation in order to built a model. For this purpose he/she will have access not only to the lab. computer facilities but also to supercomputer
centers.
Possible collaboration and networking: The student will collaborate with the experimentalists
working on this systems, namely members of the P. Foury group from the LPS (Orsay), specialists of
neutrons scattering from the LLB (Saclay) and ILL (Grenoble) neutron facilities. The student will also
collaborate with theoreticians from ILL in particular E. Rebolini.
Possible extension as a PhD
Required skills: The student should have a good knowledge of quantum mechanics, as well as
knowledge of computers usage.
Starting date: between January and March 2019, end date not after July 31st.
Contact: Name: Marie-Bernadette Lepetit - Institut Néel - CNRS Phone: (+33) 4.76.88.12.89 e-mail: Marie-Bernadette.Lepetit@neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
38
Elaboration of Ln3+-doped α-La(IO3)3 thin films
General Scope:
Iodate crystals (α-La(IO3)3) present a high dielectric
susceptibility (χ2), leading to promising applications
in piezoelectricity and non-linear optics.1 In
addition, the possibility of substituting La3+ ions by
some trivalent luminescent lanthanide ions adds up
the photoluminescence as a new functionality. In
this context, we have successfully developed Er3+-
doped α-La(IO3)3 nanocrystals (size <100 nm),
exhibiting both Second Harmonic signal and up-
conversion luminescence under a near-infrared
excitation.2 One of the biggest challenges is now to
be able to deposit these compositions as thin films
for a good integration in electronic devices.
1 K. M. Ok, P. S. Halasyamani. Inorg Chem (2005) 2 S. Regny, J. Riporto, Y. Mugnier, R. Le Dantec, I.
Gautier-Luneau, G. Dantelle, in preparation
Research topic and facilities available: Lanthanide-doped α-La(IO3)3 nanoparticles are currently synthesized by microwave-assisted
hydrothermal technique with a typical size comprised between 50 and 100 nm. They will be shaped as
thin films by different methods, in particular by Pulsed Laser Deposition (PLD). The deposition
conditions will be optimized to ensure the formation of the right phase, as well as a high crystal quality.
The nanocrystals and the obtained films will be characterized by X-ray Diffraction (powder and at
grazing angle, both available at the Institut Néel), as well as by Scanning Electron Microscopy. The
nanocrystal and film photoluminescence will be quantitatively studied in the lab using a
spectrofluorimeter. The Second Harmonic Generation (SHG) will be qualitatively studied at the Institut
Néel. More advanced SHG characterizations will be performed in collaboration with the Symme
Laboratory (Annecy).
Possible extension as a PhD: Yes if funding
Required skills:
Good skills in Materials Sciences (chemical synthesis, characterization techniques: XRD, SEM)
Good writing and oral skills
Starting date: February-March 2019
Contact: Geraldine Dantelle and Mathieu Salaün
Institut Néel - CNRS
e-mail: geraldine.dantelle@neel.cnrs.fr and mathieu.salaun@neel.cnrs.fr
More information: http://neel.cnrs.fr
Fig. 1. SEM image of Er3+-doped α-La(IO3)3
nanocrystals
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
39
DNA Nanostructure programming
General Scope:
The bottom-up fabrication of functional materials
opens a realm of applications, in particular in the
fields of life sciences and health. One can imagine
easily to build up in parralel and in-vivo nanocage
that would open-up and deliver drugs at the proper
target. Other applications could range from
fundamental molecular computations to enzymatic
pathway control. In fact these applications have
already been demonstrated using DNA as a
framework for molecular assembly. The design of
nanostructures is essentialy based on the
thermodynamic while their assembly is for some
part kinetically controlled. We propose to use toy
systems made of an essential element of
nanostructure assembly, the Holliday junction, to
investigate thoroughly the assembly of simple
nanostructure. The possibility to tune finelly
sequences in order to control the assembly pathway will be extensively used.
Research topic and facilities available: The internship will take place in a group interested in the thermodynamic of small systems and
biophysics. Our general goal is to investigate how heat is used at the nanoscale to drive molecular events.
We base our experiments on calorimetric measurements. We will combine these measurements with UV
absorption and gel electrophoresis to measure the thermodybamic properties and perform control
experiments. AFM analysis is also essential to our work and we benefit from the AFM platform at Neel.
Possible collaboration and networking: We collaborate with researchers in Symmes (INAC-CEA Grenoble) and in the LIMMS a joint unit of
the CNRS and the University of Tokyo in Japan.
Possible extension as a PhD:
Yes for outstanding students
Required skills:
General knowledge in thermodynamic, molecular biology a good organization and meticulous
manipulation are required. The team spirit is mellow but we expect students to get involved in their
project.
Starting date: ASAP
Contact:
Name: GUILLOU Hervé
Institut Néel - CNRS
Figure 2 Various object assembled using DNA as a
construction material
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
40
Nano-Neuroelectronics
General Scope:
While the brain is one of the most famous systems, providing and controlling every function of the
Body, it is barely understood in health and disease. New methods and new technology are required to
interrogate neuronal cells by many means and at multi-scale in-vivo, and within model neural networks
in-vitro. In particular, to understand how neural circuits operate, we need access to activity of large
numbers of neurons at the same time, and record their activity at the single cell level and at the nanoscale
regarding the lot of information which relies at the level of synapses and ion channels.
In that race, we have shown that graphene based
nanoelectronics offers an ideal platform for recording and
culturing neural networks, thanks to its flexibility,
transparency and exceptional neural affinity (Veliev 2016).
Also, the presence of readily accessible surface charges gives
the unprecedented possibility to realize a direct coupling with
cells, such the sensitivity reached in gapless graphene FET
(G-FETs) is well beyond that of current silicon technology
and allow to sense single neural spikes (Veliev et al. 2017) as
well as nanoscale event such as ion channel currents (Veliev
et al. 2018).
Research topic and facilities available: We aim to implement novel graphene based nanosensors for both in-vitro and in-vivo recording of
neuron assemblies, and combine them with several manipulation ports (optic, microfluidic and
electrical). This unique combination would allow to interrogate neuronal systems by many means and
to investigate neuronal processes within cultured and brain neuron networks.
(Veliev 2016) Veliev, F., Briançon-Marjollet, A., Bouchiat, V., & Delacour, C. (2016). Impact of crystalline
quality on neuronal affinity of pristine graphene. Biomaterials, 86, 33-41.
(Veliev 2017) Veliev, F., Han, Z., Kalita, D., Briançon-Marjollet, A., Bouchiat, V., & Delacour, C. (2017).
Recording spikes activity in cultured hippocampal neurons using flexible or transparent graphene transistors.
Frontiers in neuroscience, 11, 466.
(Veliev 2018) Veliev, F., Cresti, A., Kalita, D., Bourrier, A., Belloir, T., Briançon-Marjollet, A., ... & Delacour,
C. (2018). Sensing ion channel in neuron networks with graphene field effect transistors. 2D Materials.
Possible collaboration and networking: Such interdisciplinary project relies on strong collaborations
with numerous Physicists (theorists, material sciences, nanoelectronics, signal processing…),
Neurobiologists and Chemist at Néel and outside the lab (EPFL, IBS, IMEP, CERMAV…), as well as
‘HighTech’ plateforms for materials, nano/micro-fabrication in clean room, highly resolved microscopy
and biotechnological platform (microfluidic, cells culture, microscopy, electrophysiological setup) that
are gathered at the Néel Institut.
Possible extension as a PhD: oui
Appreciated skills condensed matter physic, nanoelectronics, materials sciences, and
electrophysiology
Starting date: March, 2019
Contact:
Name: Delacour Cécile
e-mail:cecile.delacour@neel.cnrs.fr
More information : http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
41
Ultrasensitive force measurements at the Quantum/Classical interface
General Scope: Optomechanical systems, which couples a light field
to a nanomechanical oscillator, have demonstrated outstanding
sensitivities for force measurements. Using a Silicon Carbide
nanowire coupled to a focused laser beam we already demonstrated
sensitivities in the atto-Newton (10-18 N) range [1]. Moreover the
vibrations of these wires consist in nearly degenerated and
orthogonal modes which allows for vectorial sensing capabilities
[1]. These amazing features, which have been employed to
investigate their interaction to a single spin qubit [2], will be applied
to design a new type of Magnetic Force Microscope (MFM) with a
sensitivity increased by six orders of magnitudes compared to
standard AFM/MFM probes and the ability to map the local
magnetization vector. These capabilities will be crucial to prove the
existence and reveal the fine structure of new exciting magnetic
states at room temperature. Among those, the stable chiral structure
of magnetic skyrmions [3] is very promising for future spintronics
applications and will be the focus of this project.
Research topic and facilities available: The goal of this project is to
detect, image and study the physics of magnetic skyrmions in thin
ferromagnetic films of Platinum/Cobalt. The first task will be to set up a nanowire based
MFM under vacuum, for which we have all the essential pieces and adapt and optimize new
signal processing protocols to accelerate the acquisition time. This task will be followed by
the fonctionalisation of nanowires with ferromagnetic nanoparticles. After preliminary
charcterisation of the instrument on calibrated nanostructures, measurements will be
performed on individual magnetic skyrmions.
[1] L. Mercier de Lépinay et al., Nature Nano 12, 156-162 (2016)
[2] B.Pigeau et al, Nature Comm. 6, 8603 (2015)
[3] A. Fert et al., Nature Nano. 8, 152 (2013).
Possible collaboration and networking: The Micro and Nanomagnetism group (Néel Institute)
will provide the magnetic nanoparticles as well as the thin films and magnetic dots hosting
skyrmions.
Possible extension as a PhD: The internship can move on a PhD.
Required skills: The candidate must have good experimental skills and a good knowledge in
optics. Prior experiment in magnetism is welcome. Starting date: In 2019
Contacts:
Benjamin Pigeau, Institut Néel - CNRS : benjamin.pigeau@neel.cnrs.fr
Olivier Arcizet, Institut Néel - CNRS : olivier.arcizet@neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
42
Turbulence Quantique & Vortex
Cadre général :
En dessous de 2,17 K, l’hélium liquide acquiert des propriétés
quantiques spectaculaires : écoulement sans viscosité, quantification des
mouvements tourbillonnaires... On s’attend donc à ce que sa turbulence,
appelée « Turbulence Quantique », diffère de la turbulence « classique ».
Etonnament, plusieurs études suggèrent que la seule différence entre ces
deux turbulences se concentre aux petites échelles. En particulier, en
l’absence d’un mécanisme de dissipation efficace, une accumulation
désordonnée de tourbillons de diamètre atomique (les vortex quantiques)
est prédite, mais cet effet n’a jamais été mesuré directement.
L’objectif d’un prochain Doctorat est de détecter cette éventuelle accumulation grâce à une sonde à haute
résolution, puis de modéliser ce phénomène. Outre une meilleure compréhension de la turbulence
quantique, cette étude fournira un étalon très contraignant pour des modèles numériques développés
conjointement par nos collaborateurs.
Sujet, moyens disponibles :
Une nouvelle génération de sondes micro-fabriquées de
vortex quantiques vient d’être mise au point. Ces « pinces
à second son » d’une résolution record reposent sur
l’atténuation d’ondes thermiques en présence de vortex
quantiques (cf figure). Elles seront exploitées dans nos
souffleries superfluides.
Le sujet du stage de M2 se focalisera sur un unique aspect
de ce sujet de thèse (instrumentation / mesure en soufflerie
superfluide), ou portera sur un sujet connexe
d’hydrodynamique physique cryogénique (à discuter).
Interactions et collaborations éventuelles : Cette étude s’inscrit dans le cadre d’une collaboration inter-laboratoires visant à améliorer
significativement la capacité de simulation des écoulements quantiques (Centrale Lyon/CNRS/ENS
/Univ. Grenoble-Alpes/Univ. Rouen). Des échanges réguliers auront lieu dans ce cadre.
Ce stage pourra se poursuivre par une thèse : Oui, le financement est acquis (ANR QUTE-HPC).
Formation / Compétences développées : Hydrodynamique & Turbulence quantique, Physique des
basses températures, Nanotechnologie & micro-fabrication, Traitement du signal, Instrumentation
Période envisagée pour le début du stage : indifférente
Contact : Philippe Roche, Institut Néel – CNRS/ UGA, per@grenoble.cnrs.fr http://hydro.cnrs.me
Pour candidater : merci d’envoyer CV + liste des intitulés des cours de Master (M1+M2).
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Modes de résonances d’une micro-cavité à 2nd
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présence (rouge) ou quasi-absence (bleu) de
vortex quantiques
Tourbillons superfluides
(simulations Baggaley et al.)
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
43
Superconducting Higgs mode in Monolayer systems under extreme
conditions
General Scope:
When a spontaneous breaking of a continuous symmetry takes place, for instance when crossing the normal
to superconducting transition, collective excitations of the order parameter emerge:
They are the phase modes and the massive amplitude Higgs mode, as illustrated Fig.1.
While the quest for the Higgs boson in particle physics has reached its goal and its prediction has been
rewarded with the Nobel Prize, there is growing interest in the search for analogous excitation in quantum
many body systems, notably in superconductors. Indeed, even if theoretically always here in any
superconductors and even if presented as a textbook excitation, this ‘dark’ mode (like the Higgs boson in
particle physics) remains very elusive. In principle, it does not couple to any external probe. Our purpose is
to identify and search for this Higgs mode in purely 2D monolayer systems.
Research topic and facilities available:
The compounds where a superconducting Higgs mode has been claimed to be present are the ones where
superconductivity coexists with another type of electronic order, such as charge density wave. In these systems,
like in NbSe2 (see Fig. 2), the amplitude oscillations of the CDW order parameter (CDW mode) can be detected
by Raman spectroscopy. When the system becomes superconductor, a new Raman peak emerges. It has been
attributed to the Higgs mode. Still, such Higgs mode has not been identified in purely 2D monolayer systems,
where confinement in the plane may have strong impact on its property. The student will explore mono/bilayers
systems by Raman scattering in extreme conditions of temperature and pressure, together by applying a gate.
Our goal is to discuss the universality of the detection of such mode. Technical Facilities: Glove Boxes for 2D
system exfoliation, Raman and transport measurements, clean room for contacting, High pressure cells,
cryogeny.
Possible collaboration and networking:
Collaboration between two teams of the Néel Institute (Nedjma Bendiab: Hybrid team, Pierre Rodière and
Marie-Aude Méasson: MagSup team). Theoretical collaboration with Lara Benfatto (ISC/Roma).
Collaboration with samples’ growers (Nantes, Spain). Networking: ANR project.
Possible extension as a PhD: YES.
Required skills: knowledge of condensed matter physics, curiosity, taste for delicate experiments.
Starting date: march-april 2019
Contact:
Name: Marie-Aude Méasson / Nedjma Bendiab / Pierre Rodière - Institut Néel - CNRS
e-mail: marie-aude.measson@neel.cnrs.fr / nedjma.bendiab@neel.cnrs.fr / pierre.rodiere@neel.cnrs.fr
Fig. 1: Free energy of the superconducting state versus
the superconducting order parameter (Re(Δ),Im(Δ)).
There are two types of fundamental collective
excitations. One, the amplitude Higgs mode, is the
analogous of the Higgs boson.
Fig. 2 : Raman spectra of NbSe2, a compound which
presents a charge-density-wave (CDW) mode and
may present a superconducting Higgs mode below
Tc~7K, as observed by Raman spectroscopy.
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
44
Search for new high Tc superconducting oxides
General Scope:
Unconventional superconductivity with high critical temperature (Tc) occurs by doping
two-dimensional (2D) compounds presenting an antiferromagnetic order with a high Néel
temperature (TN) and a moderate magnetic moment. This is linked to the strong exchange
interaction, responsible for antiferromagnetism but also for superconductivity. This is the case
for cuprates and iron-based chalcogenides or arsenides. Thus a reasonable strategy to find new
superconductors, based on a spin fluctuations mechanism, is to select materials with these
properties, synthesize them and chemically dope them. In particular chromium compounds are
known to have strong antiferromagnetism. These low dimensionality oxides are difficult to
synthesize, which is an important obstacle, but also allows us to be among the first to study
them recently and to understand their physics. This can be very rich, regardless of whether or
not superconductivity is obtained (Kondo Orbital effect in CrSe2 [M. Núñez et al. Phys. Rev. B.
88 (2013)]; Quantum fluctuations at 600 K in CrRe [D. Freitas et al. Phys. Rev. B. 92 (2015)]).
Even if few years ago, thinking about finding superconductivity in chromium compounds made
experts sceptical, its discovery in CrAs under pressure [Wu Wei et al. Nature Comm. 5 (2014)],
now allows to expand this type of study.
Research topic and facilities available:
We propose to perform the doping of the
Ruddlesden-Popper Æn+1CrnO3n+1 series
(where Æ is an alkaline earth, see figure) by
adequate chemical substitution. We have
already synthesized the parent phases n = 1, 2
and 3, and we have understood their physics,
thanks to a collaborative work between
experimentalists and theoreticians [Jeanneau
et al. PRL 118 (2017)]. The synthesis of these
oxides requires high pressure and high
temperature conditions, which are available in
the high-performance infrastructure of Institut
Néel. The crystallographic, electrical and magnetic properties, as well as the specific heat and
the thermal expansion of the doped samples will be probed thanks to the various experimental
setups available in our laboratory. Measurements under very high pressure, in particular
transport measurements, will complete the study.
Possible collaboration and networking:
Measurements using neutron scattering (ILL) and/or X-rays on synchrotron (ESRF) will also
be required in the medium term to understand the full set of properties. On the other hand, this
subject will benefit from interactions with the theoreticians of the laboratory or from abroad.
Possible extension as a PhD : Yes (via a selection organized by the Physics Graduate School).
Required skills : A good knowledge of the physics of condensed matter is desired.
Starting date : April 2019.
Contact : TOULEMONDE Pierre and NUNEZ-REGUEIRO Manuel
Institut Néel - CNRS : 04 76 88 74 21, pierre.toulemonde@neel.cnrs.fr;
04 76 88 78 38, manuel.nunez-regueiro@neel.cnrs.fr
More information : http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
45
New Superconductors with Iron
General Scope:
Superconducting materials convey great promises for energy saving and storage, and for reducing
our carbon footprint. This is obviously related to the possibility of electric-current transport without
dissipation, and the reduction of mechanical friction by means of magnetic levitation. At present, they are
commonly used in medical applications where they enable the generation of high and stable magnetic
fields for magnetic resonance imaging (MRI). However, a major challenge for the actual take-off of an
everyday superconducting technology lies in the discovery of appropriate materials with high
superconducting transition temperatures (Tc) and also with cheap and non-toxic elements. The project is
to investigate the potential of FeSi as a novel building block for high temperature superconductivity. This
investigation is motivated by the recent observation by the French community including the Néel Institute
of superconductivity in LaFeSiH. In this context, the student will participate in the partnership among
Grenoble, Bordeaux and Caen, highly competitive at international level.
Research topic and facilities available: Historically, superconductivity was believed not to coexist with
magnetism. This was surprisingly shown to be wrong with discovery of superconductivity in Cu and Fe-
based superconductors, both exhibiting high Tc. In the Fe-based systems a new family has been discovered
(LaFeSiH) with Tc=10K and based only on cheap and non-toxic elements. Our collaborative team aims at
studying this family, increasing the Tc, and deepen our understanding on the relationship between
superconductivity, magnetism and the changes of structure that happen to appear in the Pressure-Temperature
phase diagram. The student will perform transport, magnetic, optics, X-Ray and eventually Large Facilities
measurements (ESRF) at ambient and under pressure on the new compounds grown at Bordeaux.
Experimental Facilities : cryogeny, high pressure, transport, magnetic and optics measurements.
Possible collaboration and networking:
Networking: ANR project obtained in 2018. Collaborations: 2 teams of the Néel Institute, Bordeaux,
Caen, ESRF, Italy/Belgium/USA (DFT calculations)
Possible extension as a PhD: YES.
Required skills: knowledge of condensed matter physics, curiosity, taste for delicate experiments.
Starting date: march-april 2019
Contact:
Name: Manolo Nunez-Reguiero
Institut Néel - CNRS
e-mail: manolo.nunez-regueiro@neel.cnrs.fr
Fig. : New family of compounds we discovered in 2017 based
on Iron, a magnetic element, and Si (compared to the previous
families which required toxic/expensive elements such as As
or Se ). The resistivity versus temperature at different
magnetic field: we observe the superconducting transition at
about 10K. This family also has a complex phase diagram
under pressure which shows competing/coexisting electronic
orders (magnetism) together with superconductivity and
structural transition.
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
46
Superconducting quantum devices with topological edge channels
General Scope: Graphene is a 2D material that has attracted a considerable interest since its discovery
in 2005. Its gapless linear band structure that mimics massless Dirac fermions has led to the discovery
of a wealth of new exciting transport properties. Moreover, the possibility to engineer very high mobility
graphene devices in which electrons can travel in a ballistic fashion makes graphene the perfect
playground to investigate new quantum coherent phenomena in the quantum Hall regime, or when
coupled with a superconducting condensate.
Research topic and facilities available: Our
research focuses on coherent quantum
transport in ballistic devices. One of our main
objective is to couple topological edge
channels in graphene with superconducting electrodes to
realize topological Josephson junctions [1]. Topological edge
channels are one dimensional edge channels that emerge in
high quality graphene when a strong magnetic field drives the
system in the quantum regime. For this objective, our group
has develop state-of-the art fabrication process of high
mobility graphene devices by encapsulation of graphene
monolayers between insulating boron-nitride flakes [2], so-
called van der Waals heterostructures.
We have an open Master/PhD position to study hybrid devices
that couple superconducting electrodes with ballistic graphene
to realize superconducting quantum devices such as gate-
tunable Josephson junctions. The objective of the Master internship is to fabricate and perform
preliminary characterization by quantum transport measurements (down to T=0.01K and up to B=18T)
of high mobility graphene Josephson junctions made with a high critical-field superconductor
(amorphous indium oxide [3]). The capability of the superconducting electrodes to withstand a high
magnetic field will enable to make pioneer investigation of Josephson junctions and more advanced
devices in the quantum Hall regime under strong magnetic field (PhD research program).
[1] Joule overheating poisons the fractional ac Josephson effect in topological Josephson junctions.
Le Calvez, et al. arXiv:1803.07674 (2018)
[1] Tunable transmission of quantum Hall edge channels in split-gated graphene devices. K.
Zimmermann, et al. Nature Communications 8:14983 (2017)
[3] Low temperature anomaly in disordered superconductors near Bc2 as a vortex glass properties. B.
Sacépé et al. arXiv:1609.07105 Nature Physics in press (2018)
Possible extension as a PhD: YES (supported by an EU grant)
Required skills: We look for highly motivated students with a good background in condensed matter
physics / quantum physics, and which are willing to address fundamental questions at the frontier of
quantum solid-states physics. Notice that lab visits are highly encouraged.
Starting date: Flexible
Contact: SACEPE Benjamin ( benjamin.sacepe@neel.cnrs.fr )
Website: http://sacepe-quest.neel.cnrs.fr/
Figure | Left, SEM picture of graphene Josephson junctions devices. Right, differential resistance of a junction showing a superconducting branch (black area) that is modulated by a back gate electrode voltage Vg.
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
47
Localized Cooper-pairs in disordered superconductors
General Scope: When a superconducting disordered thin film
is subjected to an increase of disorder or to a strong magnetic
field (B) it can undergo a transition to an insulating state. This
transition is a quantum phase transition occurring at T=0
between two antinomic ground states: The superconducting
and insulating ground states. The fundamental question
underlying this superconductor-insulator transition (SIT) is
whether Cooper pairing responsible for superconductivity dies
out at the critical disorder (or B), or survives beyond, that is, in
the insulating state. In recent years a body of work has shown
that in some amorphous superconductors the Cooper pairing
actually persists in the insulator, forming a new sort of
insulator called “Cooper-pair insulator”. The unusual nature of
this insulator and of the superconducting state that precedes it
is nowadays drawing considerable interest.
Research topic and facilities available: Our research
program focuses on both the superconducting and insulating
sides of the transition. We study mainly amorphous indium
oxide [1,3] and molybdenum-germanium thin films and
nanowires [2]. The goal of this Master project will be to
investigate the role of Coulomb interaction in the suppression
of the critical temperature of thin films. We will use our know-how in van der Waals heterostructures
to exfoliate flakes of insulating boron-nitride (BN) on a high dielectric constant substrate. E-beam
lithography will be carried out to design samples on micron size flakes. By varying the thickness of the
BN microcrystal, we will vary the distance to the high dielectric constant substrate that serves as a
screening plate, and thus tune the strength of Coulomb interactions. This study will provide crucial
information on the role of correlations and charging effects in the suppression of Tc and the formation
of the Cooper-pair insulator. For the PhD perspective, efforts will be focused on two important
objectives; i) investigating the critical point of the B-tuned SIT, and ii) performing innovative high
frequency measurements of the dielectric properties of the Cooper-pair insulator using state-of-the-art
superconducting micro-wave resonators.
[1] Localization of preformed Cooper pairs in disordered superconductors, B. Sacépé et al. Nature Physics 7,
132 (2011). arXiv:1012.3630
[2] Pair-breaking quantum phase transition in superconducting nanowires. H. Kim et al. Nature Physics AOP
(2018)
[3] Low temperature anomaly in disordered superconductors near Bc2 as a vortex glass properties. B. Sacépé et
al. arXiv:1609.07105 Nature Physics in press (2018)
Possible extension as a PhD: YES
Required skills: We look for highly motivated students with a good background in condensed matter
physics / quantum physics, and w hich are willing to address fundamental questions at the frontier of
quantum solid-states physics. Notice that lab visits are highly encouraged.
Starting date: Flexible
Contact: SACEPE Benjamin ( benjamin.sacepe@neel.cnrs.fr )
Website: http://sacepe-quest.neel.cnrs.fr/
Figure | The SIT is easily tuned in experiments by applying a strong perpendicular magnetic field to a thin superconducting films. The figure shows a typical B-tuned transition from superconductor at B=0 to the Cooper-pair insulator at finite B with a diverging resistance at the lowest T.
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
48
Search for new high Tc iron-based superconductors
General Scope:
The mechanism of high Tc superconductivity remains an open question in condensed matter
physics. Such superconductors show record Tc values of 135K for Cu-based families and 55K
for iron-based arsenides and chalcogenides (and even above 77-100K in FeSe monolayer) at
ambient pressure. The electron-phonon coupling is too weak in these layered materials to
explain their high Tc, other mechanism such as spins fluctuations has to be involved. In 2014
superconductivity was evidenced in in another Fe-based superconductor, YFe2Ge2 [Zou et al.
Phys.Stat.Sol. 8 (2014), see first figure], showing also Fe in tetrahedral coordination (with Ge).
Very recently, thanks to collaboration between
ICMCB and Néel Institute, superconductivity at
Tc~10K has been discovered in LaFeSiH (see
second figure), i.e. an analogous layered compound
without toxic element like arsenic [Bernardini et al.
PRB: Rapid Comm. 97 (2018)). A long term
project, involving our laboratory and starting in
December 2018, aims to extend this new FeSi-
based superconducting family and understand their
properties.
Research topic and facilities available:
During this M2 internship we propose to use a high pressure – high
temperature process to 1) directly synthesize LaFeSiH from
precursors such as LaH3 (or anthracene as H source), La, LaSi,
Fe or FeSi, then 2) to try the Si substitution by Ge and H
substitution by F or O substitution and 3) possibly extend the
work to the study the related (Y,Ca)Fe2(Ge1-xSix)2 solid solution.
The crystallographic, electrical and magnetic properties, as well
as the specific heat of the different samples will be probed thanks
to the various experimental setups available in our laboratory.
Measurements under very high pressure, in particular transport
measurements, will complete the study.
Possible collaboration and networking:
Since the discovery of superconductivity in iron-based compounds, an important knowledge of
this family has been developed in our laboratory. The candidate will benefit of it and will have
the opportunity to interact with several collaborators at NEEL Institute, in particular with
theoreticians, but also outside from Grenoble.
Possible extension as a PhD : Yes (via a selection organized by the Physics Graduate School).
Required skills : The candidate must have a good background in solid state physics, crystallography
and material science.
Starting date : April 2019.
Contact : TOULEMONDE Pierre and NUNEZ-REGUEIRO Manuel
Institut Néel - CNRS : 04 76 88 74 21, pierre.toulemonde@neel.cnrs.fr;
04 76 88 78 38, manuel.nunez-regueiro@neel.cnrs.fr
More information : http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
49
Search for superconductivity under pressure in mono and bi-layer
graphene
General Scope:
The multiplication of the studies on graphene have resulted in a large number of the new applications.
However, very few experimental studies have been performed on his electronic properties under
pressure. Certainly, few changes are expected under pressure on the graphene mono-layer as it is
extremely hard in the basal plane. However, in our preliminary measurements shown in the figure, it is
clear that the resistance of the graphene sample changes enormously under pressure due to doping
effects. We intend to optimize this doping under pressure to over-dope single layer graphene and attain
the level where it has been predicted to be a chiral
superconductor [Nature
Phys. 8 (2012) 158].
Furthermore, the physics
of bi-layers under pressure
is certainly very rich. For
example, two graphene
monolayers, stacked in a
Moiré pattern by a small
angle rotation, have been
recently shown to be
superconducting at low
temperatures [Nature
556(2018)43]. We plan to
study the effect of pressure
on the Tc of Moiré bilayers. Finally, Van-der-Waals
bonding between two layers of graphene is weak and should be sensitive to pressure, that will deform a
bi-layer of graphene towards a diamond symmetry. Theoretical calculations have predicted these
structures to be superconductors [PRL 111(2013)066804].
Research topic and facilities available: The subject of the internship will consist in a first stage in the adaptation, for its assembly in the high-
pressure cells, of the graphene single and double layer samples, synthesized in collaboration with V.
Bouchiat of the HYBRID Team. The student will thus acquire a solid experience in nanofabrication. He
will proceed then to make transport measurements as a function of temperature down to 1K in both
piston-cylinder systems (P<2GPa; with P. Rodière, MagSup team) and in Bridgman cells (<30GPa; with
M. Nunez-Regueiro and M-A. Measson MagSup Team). These measurements will enrich his knowledge
of electronic properties of two-dimensional materials.
Possible collaboration and networking: The student will collaborate with colleagues of different Néel Institute departments.
Possible extension as a PhD: YES
Required skills: Good knowledge of condensed matter physics, curiosity, taste for delicate
experiments
Starting date:march-april 2019
Contact:
Name: Manuel Núñez-Regueiro
Institut Néel - CNRS
e-mail: nunez@neel.cnrs.fr
More information: http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
50
Degradable organosilica nanoparticles for controlled drug delivery
Summary:
Porous organosilica nanoparticles will be prepared to be used as nanovehicles for controlled drug
delivery of anti-cancer drugs. Their structure will feature organic fragments that will be cleaved in
cancer cells, leading to the overall degradation of the nanoparticle after or concomitantly with the release
of the drug.
Detailed subject:
Periodic Mesoporous Organosilicas are attracting considerable attention for application in catalysis,
optics or drug delivery [1]. These materials of general formula O1.5Si-R-SiO1.5, where R is an organic
group, are obtained by the sol-gel hydrolysis-condensation of organo(trialkoxy)silanes in the presence
of surfactants. They advantageously combine organic fragments linking inorganic siloxane domains.
Recently, the first nanosized PMOs have been produced with variable mesoporous structures depending
on the nature of the organic linker [2]. These nano-PMOs are very promising for controlled drug
delivery, as they feature an important mesoporosity, but also an organic substructure allowing a strong
hydrophobicity, suitable to interact with lipophilic drugs.
The elimination of the nanoparticles after drug delivery is of major concern. Therefore, we recently
designed nano-PMOs containing S-S bonds that are easily cleaved in cells. This allowed to the
destruction of the nano-PMOs under biological conditions [3].
The aim of this Master 2 internship is to prepare and characterize new types of PMO nanoparticles that
would be degradable under biological conditions, and to evaluate their potential in controlled drug
delivery. The syntheses will be performed either in solution or by spray-drying.
References:
Croissant, J.; Cattoen, X.; Wong Chi Man, M.; Gallud, A.; Raehm, L.; Trens, P.; Maynadier, M.;
Durand, J.-O., Adv. Mater. 2014, 26, 6174-6180.
Croissant,J.; Mauriello-Jimenez,C.; Maynadier, M.; Cattoën, X.; Wong Chi Man, M.; Raehm, L.;
Mongin, O.; Blanchard-Desce, M.; Garcia, M.; Gary-Bobo, M.; Maillard, P.; Durand, J.-O. Chem.
Commun. 2015, 12324-12327.
This Master internship may be extended into a PhD within the same research subject.
Background and expected skills:
Good knowledge in characterization techniques (spectroscopies, microscopies) and basic knowledge
in molecular and sol-gel chemistry are required.
Expected starting date: feb 2019
Contact: CATTOEN Xavier
Institut Néel - CNRS : 04-76-88-10-42 ; xavier.cattoen@neel.cnrs.fr
More information on: http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
51
Controlled nucleation and growth of molecular nanocrystals for
biophotonics and advanced solid-state NMR General Scope: We develop the synthesis of highly fluorescent tracers for biological imaging based on
two-photon fluorescence scanning microscopy. These tracers (50-100 nm) are based on molecular
nanocrystals (NCs) constituted by a high number of molecules (105-106) allowing their good
photostability and high cross sections of absorption and fluorescence emissions. This leads to bright
tracers to increase fluorescence contrasts and 3D imaging in the depths of biological tissues. On the
other hand, the shaping of organic NCs in solutions allow to enhance the sensitivity (by several orders
of magnitude) and the resolution of a just emerging method of magnetic resonance spectroscopy called
Magic Angle Spinning - Dynamic Nuclear Polarization (MAS-DNP), developed at CEA-INAC
Grenoble. This MAS-DNP spectroscopy will be used for 3D structure determinations (NMR
crystallography) of many solid-state systems, which do not easily form large enough crystals (>100 m)
required for single crystal X-ray diffraction studies and cannot be easily isotopically enriched in 13C and 15N. Thus, such developments are highly relevant, especially for supramolecular systems, drugs, natural
products, self-assembled peptides/nucleotides… etc.
Research topic and facilities available: The objective will be to control the confined nucleation and
growth of molecular NCs in droplets of organic solvents. For that, different organic compounds will
be dissolved in solvents miscible with water (alcohols, THF, dioxane…). The resulting solutions will
be sprayed and suddenly dispersed in water. As water is generally a non-solvent for molecular phases,
the corresponding NCs will grow when the solvent droplets will be gradually mixed in water. We
recently made a step-forward in the control of this process by producing nanometer-sized crystals of
progesterone (around 50 nm in diameter) as shown by scanning electron microscopy in the figure
below. The goal is now to produce monodisperse initial droplets to obtain then narrow size
distributions of NCs (50-100 nm) by optimizing the nanocrystallization reactor and confined
nucleation conditions. The resulting NCs will be characterized by X-ray diffraction, electron
microscopies (SEM and TEM), dynamic light scattering, Raman and fluorescence spectroscopies. This
research is part of a highly challenging ERC (European Research Council) project on developments
of MAS-DNP spectroscopy. Indeed, we believe that our generic process will be widely applicable for
molecules exhibiting both a significant solubility in solvents miscible with water and a negligible
solubility in water, which is the case of a large number of organic compounds. Finally, we will plan to
couple this confined nanocrystallization method in solutions to sol-gel chemistry, in order to prepare
through a one-step process core-shell nanoparticles: fluorescent NCs surrounded by an amorphous
silicate crust for medical imaging applications (highly fluorescent tracers).
Nanocrystals of progesterone obtained from a methanol solution sprayed and injected in water.
Possible collaborations and networking: INAC-CEA, ENS Lyon, INSERM Lyon
Possible extension as a PhD: Yes
Required skills: Solid-state and physical chemistry, basic knowledge on physicochemical and
structural characterizations of materials. Starting date: 2018-19
Contact : Alain Ibanez, Institut Néel, CNRS. Phone: 0476887805 e-mail: alain.ibanez@neel.cnrs.fr
More information: http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
52
White phosphors for LED lighting prepared by sol-gel method
General Scope: White LED lighting (wLED) has become a major challenge for energy saving.
wLED involve a phosphor (phosphor-coated LEDs, pc-LEDs), to convert the initial diode emission in
white light. The defect-based luminescent materials are a promising alternative to lanthanide or
transition metal activators doped phosphors for a lot of applications due generally to their main
advantages of good thermal and chemical stabilities, tunable emission color and low-cost price. At
Institut Néel, we have developed for several years original lanthanide-free phosphors for wLED, which
are patented. These phosphors are amorphous yttrium aluminum borate micro-powders around the
YAl3(BO3)4 stoechiometry. The innovative nature of these powders is to produce a broad band of white
luminescence emission throughout the visible spectrum by excitation in the near UV (370-390 nm) due
to emitting centers trapped in the stable amorphous matrix. It is thus possible to produce comfortable
white light for eyes with excellent color rendering index. Recently, we have identified the nature of
emitting centers, which are small aromatic molecules formed during the thermal treatments. These
pioneering works published recently open up a field of research that is extremely promising from both
for fundamental works and applications: photoluminescence (PL) efficiency, colorimetric emission
quality and very good stability.
Research topic and facilities available: Based on these promising results, this project will be to
optimize the synthesis of metal aluminum borate powders by sol-gel route varying chemical factors.
Different metals with lower coordination number and stoichiometric ratios of molecular precursors
(allowing metal complexation and polymerization of organic-inorganic network) will be tested. The
change of chemical composition should enable both to adjust the width of the PL emission for better
colorimetry and to enhance the PL efficiency. The size, shape and composition of phosphors play a
considerable role in tailoring the optical properties of pc-LEDs. For this reason, a special effort will be
made to control the morphologies of these powders using a high pressure/temperature drying of
alcoholic gels under supercritical conditions, followed by thermal treatments in controlled atmosphere.
The obtained powders are characterized by various techniques, including X-ray diffraction, Differential
Thermal Analysis-Thermogravimetry coupled with Mass Spectrometry, infrared spectroscopy, Nuclear
Magnetic resonance, Scanning Electron Microscopy and Photoluminescence spectroscopy.
Amorphous YAB powders exhibit PL from blue
emission for powders calcined at 450 °C to broad
white PL for higher calcination temperature. Small
aromatic molecules providing from decomposition
of propionate ligands are trapped within the
inorganic matrix.
Possible collaboration and networking: Institut de Recherche Chimie-Paris ; INAC-CEA Grenoble
Possible extension as a PhD: Yes
Required skills: Chemistry in solution, knowledge on physicochemical and structural characterizations of
material
Contact : Pr Gautier-Luneau Isabelle
Institut Néel – CNRS
Phone: 04 76 88 78 04 e-mail: Isabelle.Gautier-Luneau@neel.cnrs.fr
More information: http://neel.cnrs.fr
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
53
Molecular spin devices for quantum processing
General Scope:
The realization of an operational quantum computer is one of the
most ambitious technological goals of today’s scientists. In this
regard, the basic building block is generally composed of a two-
level quantum system (a quantum bit). It must be fully controllable
and measurable, which requires a connection to the macroscopic
world. In this context, solid state devices, which establish electrical
connections to the qubit are of high interest. Among the different
solid state concepts, spin based devices are very attractive since
they already exhibit long coherence times.
Electrons possessing a spin 1/2 are conventionally thought as the natural carriers of quantum information, but
alternative concepts make use of the outstanding properties of molecular magnets as building blocks for
nanospintronics devices and quantum computing. Their spin benefit from longer coherence times compared to
purely electronic spins. In this context, our team combines the different disciplines of spintronics, molecular
electronics, and quantum information processing. In particular, we fabricate, characterize and study molecular
spin-transistor in order to manipulate[1] and read-out an individual spin[2] to perform quantum operations[3].
[1] S. Thiele, F. Balestro, R. Ballou, S. Klyatskaya, M. Ruben, W. Wernsdorfer, Science 2014.
[2] R. Vincent, S. Klyatskaya, M. Ruben, W. Wernsdorfer, F. Balestro. Nature 2012.
[3] C. Godfrin, R. Ballou, S. Klyatskaya, M. Ruben, W. Wernsdorfer, F. Balestro, Phys. Rev. Lett. 2018.
Research topic and facilities available: Nano-devices addressing single molecular spins will be designed and
reliable methods for their realization and caracterization will be developed. Our team has a strong experience
in molecular magnetism, nanofabrication, ultra-low noise transport measurements, microwave electronics and
cryogenic equipment. We propose to use molecular spins as platform to perform multiqubit algorithms. Single
molecular units are embedded in scalable electronic circuits and individual spin read out is performed by
molecular (or carbon-based) quantum dots. The key experiment will be the demonstration of two qubit gate to
complete the set of universal gates for scalable architectures. The student will fabricate the samples using the
clean room facilities of the Néel Institut. She/he will carry out the measurements of the device at very low
temperature (20mK), using one of the six fully equipped dilution refrigerators of the team, in order to create,
characterize and manipulate single spin using spin based molecular quantum dot.
Possible collaboration and networking: This multidisciplinary research field is based on years of
collaborations with teams from different scientific and technical cultures (cleanroom, technicians,
collaborations with chemists and theoreticians, ...), in the framework of European projects and different
national and regional funding.
Possible extension as a PhD: Yes
Required skills: We are looking for a motivated student who is interested in experiments that are challenging
from the experimental point of view.
Starting date:
Contact: BALESTRO Franck, Institut Néel - CNRS - UGA
Phone: 04 76 88 79 15 e-mail: franck.balestro@neel.cnrs.fr
More information: http://neel.cnrs.fr/spip.php?rubrique51
NÉEL INSTITUTE Grenoble
Topic for Master 2 internship – Academic year 2018-2019
54
Interfacing molecular spins with nanomechanical oscillators in the quantum
regime
General Scope: The spin degree of
freedom is a natural candidate to carry
quantum information. Because of a
generally weak coupling to its
environment, it benefits from long
lifetimes even in solid-state devices. The
counterpart of this natural isolation is the
challenge to engineer strong coupling
between distant spins, which is
fundamental requirement to perform
quantum computations [1]. Among the
various types of existing spin systems,
molecular spins have shown remarkable properties in transistor devices [2], and they have already been used
to perform basic quantum information processing tasks [3]. It is known that in a solid state context, the
dominant source of decay for molecular spins comes from the coupling to mechanical modes via spin-phonon
coupling [4]. These phonons could be seen as a nuisance, but they actually constitute an interesting degree of
freedom that has recently been intensely investigated in the field of circuit quantum electromechanics. Our
strategy is to take advantage of the natural spin-phonon coupling in molecular magnets and use phonons as a
resource to control and readout molecular spins on fast time scales, using the powerful circuit quantum
electromechanics techniques [5]. Such an interface could enable the coupling of distant molecular spins, but
also the coupling to other degree of freedom such as microwave and optical photons, superconducting qubit or
other spin systems.
[1] J. J. Viennot, M. C. Darthiail, A. Cottet, T. Kontos, Science 2015
[2] S. Thiele, F. Balestro, R. Ballou, S. Klyatskaya, M. Ruben, W. Wernsdorfer, Science 2014.
[3] C. Godfrin, K. Ferhat, R. Ballou, S. Klyatskaya, M. Ruben, W. Wernsdorfer, F. Balestro, Phys. Rev. Lett. 2018.
[4] M. Ganzhorn, S. Klyatskaya, M. Ruben, W. Wernsdorfer, Nature Comm. 2016
[5] J. J. Viennot, X. Ma, K. W. Lehnert, (under review) arXiv 1808.02673 2018
Research topic and facilities available: The purpose of this internship is to develop mechanical oscillators
made out of graphene or carbon nanotubes, which will maximize the spin-phonon coupling while being
embedded in superconducting microwave circuits compatible with quantum electromechanics techniques. Our
team has a strong experience in molecular magnetism, nanofabrication, microwave electronics and cryogenic
equipment. The student will design and fabricate devices, and will perform microwave measurements at
cryogenic temperatures (20 mK) using one of the fully equipped dilution refrigerators of the team.
Possible collaboration and networking: This multidisciplinary research field is based on years of
collaborations with teams from different scientific and technical cultures (cleanroom, technicians, theorists,
collaborations with chemists), in the framework of European projects and various national and regional
funding.
Possible extension as a PhD: Yes. PhD fellowship available.
Required skills: We are looking for a motivated student who is interested in learning a wide variety of skills
and being part of an experiment involving both technical and fundamental challenges.
Starting date: flexible
Contact: VIENNOT Jérémie (jeremie.viennot@neel.cnrs.fr)
BALESTRO Franck (franck.balestro@neel.cnrs.fr)
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