Bismuth based topological Josephson junctions · Li Jorrit de Boer Bob de Ronde University of...

University of Twente, the Netherlands

Alexander Brinkman

Bismuth based topological

Josephson junctions

IEEE CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), November 2019. Invited presentation 3-EO-TS-02l given at EUCAS, 1 – 5 September 2019, Glasgow, UK.

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UNIVERSITY OF TWENTE.

Acknowledgements

University of Twente

Yingkai Huang

Anne de Visser

Erik van Heumen

Mark Golden

MartijnLankhorst

Chuan

LiJorritde Boer

Bobde Ronde

University of Amsterdam

Peter Schüffelgen

Daniel Rosenbach

Thomas Schäpers

Detlef Grüzmacher

Forschungszentrum Jülich


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Message of this talk

3D helical spin-momentum locking

of Dirac semimetal

- Topological transport

- 4p-periodic Andreev bound states

- Zeeman induced p-junction


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Non-Abelian anyons

“Qubits stored in topology are less likely

to be affected by their environment.”

Microsoft

Non-Abelian anyons


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Majoranas in superconductors?

Bogoliubov quasiparticles:

Needed for Majorana:

Zero energy state required


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Spin-momentum locking

Adv. Electr. Mater. 201900334 (2019)


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Topology and superconductivity

3D chiral p:3D s-wave:


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PdTe2 type II Dirac semimetal

Dominant s-wave superconductor…

Phys. Rev. B 99, 014510 (2019)


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NS S

NS S

TIS S

Calculations and figure

from Badiane,Meyer, HouzetStandard SNS:

Including interface barrier:

With topological interlayer:

Why topological Josephson junctions?


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Majorana manipulation on a surface

Fu & Kane, PRL 100, 096407 (2008)

Phase


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Advanced device fabrication

In situ electrode deposition by shadow mask technology

Selective area growth

enhanced IcRn

towards 1D


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Advanced device fabrication

Nature Nanotechnology 14, 821 (2019)


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Majoranas

1D Nanowires (InAs, InSb… )Strong evidence (Delft, Lund, Copenhagen)

SSS S

1D edges of 2D QSH (HgTe)Strong evidence (Würzburg)

S

3D bulk states (Dirac/Weyl semimetals)This talk

DSM

SS S

2D surface states of 3D topological insulators

(Bi2Se3, Bi2Te3, Bi1Sb1Te1Se2)First signatures

TI


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Sb doping concentration3%0%

3D Dirac semimetal Bi1-xSbx

“3D graphene”


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Surface (111) of Bi1-xSbx

Angle resolved photoemission

spectroscopy (ARPES):

electrons: 1-2 x 1012 cm-2

holes: 1-2 x 1012 cm-2


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Quantum oscillations of bulk holes


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Multiband magnetotransport

Electrons in the bulk Dirac cone:


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Negative longitudinal

magnetoresistance (LMR)

3%✔ 4%✘

Chiral anomaly in Bi1-xSbx

Polarization of chirality:

Analogy pion decay:


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Monopole diffusion

Phys. Rev. B 99, 085124 (2019)


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Bi1-xSbx Josephson junctions

Bi1-xSbx

Nb

Nature Mater. 17, 875 (2018)


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Ballistic 500 nm Josephson junctions:

Bi1-xSbx Josephson junctions, x=0.03

Transparency = 0.9


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Observation of 4p-periodic supercurrent

Microwave irradiation:


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From the critical frequency we obtain: I4p > 20% of Ic

Recovery of 2p-periodicity


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Non-perpendicular trajectories

Towards single channel:

1. Quantization of tranverse

momentum

2. Including a magnetic layer

M. Snelder, M. Veldhorst, A.A. Golubov, A. Brinkman, Phys. Rev. B 87, 104507 (2013)


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‘Majorana’ percentage


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0 p

Giant Zeeman effect in Dirac cone

with g = 1000


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S3 (accidental) SQUIDAsymmetric SQUID for current-phase relation


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0 – pi transitions

Phys. Rev. Lett. 123, 026802 (2019)


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Conclusion and outlook

• Josephson supercurrent observed in several topological

Josephson junctions

• Largest Majorana signal in the 3D Dirac semimetal

• Thin films & gating needed

• Majorana character: Fu-Kane type experiment


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Outlook: Majorana vortex lattice

dimensionless self inductance of the loop


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Using local current pulses instead of flux biasing

Compatible with GHz rapid single flux quantum (RSFQ) technology?


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Using global current pulses and trap sites


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Bismuth based topological Josephson junctions · Li Jorrit de Boer Bob de Ronde University of...

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