4 Department of Chemistry, University of Warwick, … · 4 Department of Chemistry, University of...
Transcript of 4 Department of Chemistry, University of Warwick, … · 4 Department of Chemistry, University of...
Molecular SpintronicsGabriel Aeppli 1, Andrew Fisher 1, Nicholas Harrison 2, Sandrine Heutz 3,
Tim Jones 4, Chris Kay 5 and Des McMorrow 1
1 Department of Physics and Astronomy, London Centre for Nanotechnology, University College London, London WC1E 6BT, U.K.2 Department of Chemistry, London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, U.K. 3 Department of Materials, London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, U.K.
4 Department of Chemistry, University of Warwick, Coventry, CV4 7AL, U.K.5 Department of Biology, London Centre for Nanotechnology, University College London, London WC1E 6BT, UK.
• Funded through the Basic Technology programme
• November 2008 start, duration 4 years.
• Includes 3 institutions (Warwick, UCL and Imperial) and 7 investigators.
• Crossing boundaries: PIs experts in different branches of Science (Chemistry, Physics, Biology) and Engineering (Materials, EE).
• Directly employs 4 PDRAs and 3 PhD students
• Project extends boundaries: Additional academics (a.o. Hirjibehedin, Curson, Nathan, Ryan), more than 7 PhD students and PDRAs closely linked to the project
Combine cheap organic electronics and high performance spintronics
to develop molecular spintronics with outcomes in IT and biosensing.
Use expertise in small molecule film growth, magnetism, theory,
optoelectronics, device engineering and spin resonance applied to
biology.
Molecular Electronics
OPV, OLED,
Transistors
Semicond. polymers
and molecules
Spintronics
GMR, MRAM
Magnetic HJ
Magnetic
Semiconductors
Organic Spintronics
Molecular films
as tunnelling layers
Molecules
on magn. surfaces
Molecular Magnetism
Magnetic switching,
spin-crossover
Molecular powder,
e.g. Prussian Blue
BT Molecular
SpintronicsUnique combination of
properties
Xiong, Nature 04
Baibich, PRL88
Verdaguer, Science 96
Nelson, Durrant (IC), Forrest
Applications in IT
Combine magnetic
centre (Q-bit) with
semiconducting
ring (control)
N
N-
N
N-
N
N
N
N
Cu2+
Exploit spin and
magnetism in
optoelectronic
devices based on
organometallics
Applications in
Biosensing
Label-free detection
based on specific
spin relaxation
Key Publications and Patents
• A Novel Route for the Inclusion of Metal Dopants in Silicon,
Nanotechnology 21 (2010) 035304.
• Ultralong copper phthalocyanine nanowires with new crystal structure
and broad optical absorption, ACS Nano 4 (2010) 3921-3926.
• Morphology and Structure Transitions of Copper
Hexadecafluorophthalocyanine (F16CuPc) Thin Films, J. Phys. Chem. C
114 (2010) 1057.
• Theoretical modeling of exchange interactions in Cu(II)Pc one-
dimensional chain, Phys Rev B (2011) – in press.
• Spin-based diagnostic of nanostructure in films of a common
molecular semiconductor – submitted.
• Patent: A Novel Route for the Inclusion of Metal Dopants in Silicon
(GB0908254.6).
Further fundingProject is a platform for further funding, including EPSRC-NSFC grant in
Foundations of Molecular Nanospintronics.
Key issue: efficiency of organic devices strongly depends on
molecular orientation. However, diffraction cannot always be applied in
poorly crystallised systems.
Objectives: use spin resonance lineshapes and positions to determine
local order and orientation of dye molecules in test systems and apply
to rationalisation of solar cells
Film B perp
( = 90°)
B parallel
( = 0°)
On glass g┴ g// and g┴
Templated g// g┴
B “parallel” ( = 90°)B “perpendicular” ( = 90°)
g//
gperp
gperp
g//
CuPc on glass CuPc templated
Top view of molecules on substrate g-factors observed
Field (mT)
Orienta
tion ()
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Film on glass Templated CuPc:C60 mixed
Unexpected benefit of BT project for energy sector:
• molecular spins as an inexpensive in-line quality
control tool to measure mol. orientation
• clustering and preferential orientation with
molecules perp to substrate in mixed CuPc:C60
• unfavourable orientation of molecules in mixed
solar cells, points to path for increased efficiency
Main Milestones Nanowire film and FET
Set of rules for correlation between molecular parameters and
exchange couplings
EPR Hamiltonian
• Thin film Tc above 77K
• Optical control of exchange interactions
• EPR detection of biomolecules based on antibody/antigen interactions
• Magneto-optic phenomenology and EPR Hamiltonian for bioassay
400 nm1 cm N2 20 nm
d001
Nanowires and films are essential for miniaturisation of spintronic device
and efficient spin transport through single crystal domains
CuPc by Organic Vapour Phase Deposition
Based on molecules in a 3-zone furnace and inert carrier gas wires with
new crystal structure, high flexibility and aspect ratios approaching CNTs
alpha
wire
beta
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No
rma
lise
d m
ag
ne
tisa
tio
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m0H (Tesla)
Magnetic properties show that wires have
antiferromagnetic coupling, as rationalised by
theoretical calculations.
High orbital overlap along long axis should
mediate high anisotropic conductivity.
Increasing Tc using different transition metal derivatives
Project Organisation
Engineering Application: new route to
determine local order in organic solar cells
Visibility and Outcomes
Science Application: molecular magnetic
wires and films from vapour
Project Summary and Context
Thin films grown using organic molecular beam deposition
0 20 40 60 80
0.0
3.0x107
6.0x107
9.0x107
1.2x108
1.5x108
-1 (
Oe
/em
u)
Magnetisation
Ferromagnetic film
with Tc ~26 K
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
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m0H (Tesla)
m0H (Tesla)
M n
orm
alis
ed
at 7
T