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Molecular Spintronics Molecular Spintronics Gabriel 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. Project Organisation Project Summary and Context Combine cheap organic electronics and high performance spintronics • Funded through the Basic Technology programme to develop molecular spintronics with outcomes in IT and biosensing. • November 2008 start, duration 4 years. Use expertise in small molecule film growth, magnetism, theory, • Includes 3 institutions (Warwick, UCL and Imperial) and 7 investigators. optoelectronics, device engineering and spin resonance applied to • Crossing boundaries: PIs experts in different branches of Science (Chemistry, Physics, Biology) and Engineering (Materials, EE). biology. • Directly employs 4 PDRAs and 3 PhD students Molecular Electronics Spintronics • Project extends boundaries: Additional academics (a.o. Hirjibehedin, OPV, OLED, GMR, MRAM Curson, Nathan, Ryan), more than 7 PhD students and PDRAs closely Transistors Magnetic HJ Semicond. polymers Magnetic linked to the project and molecules Nelson, Durrant (IC), Forrest Baibich, PRL88 Semiconductors Organic Spintronics Molecular Magnetism Molecular films Magnetic switching, as tunnelling layers spin-crossover Visibility and Outcomes Molecules BT Molecular Molecular powder, on magn. surfaces Xiong, Nature 04 Spintronics Verdaguer, Science 96 e.g. Prussian Blue Unique combination of Key Publications and Patents properties • A Novel Route for the Inclusion of Metal Dopants in Silicon, Applications in IT Exploit spin and Applications in Nanotechnology 21 (2010) 035304. magnetism in Biosensing Combine magnetic optoelectronic • Ultralong copper phthalocyanine nanowires with new crystal structure centre (Q-bit) with devices based on Label-free detection and broad optical absorption, ACS Nano 4 (2010) 3921-3926. semiconducting organometallics based on specific N spin relaxation • Morphology and Structure Transitions of Copper ring (control) - N N 2+ N Cu N - Hexadecafluorophthalocyanine (F16CuPc) Thin Films, J. Phys. Chem. C N N 114 (2010) 1057. N • Theoretical modeling of exchange interactions in Cu(II)Pc one- dimensional chain, Phys Rev B (2011) – in press. Main Milestones • Spin-based diagnostic of nanostructure in films of a common Nanowire film and FET molecular semiconductor – submitted. Set of rules for correlation between molecular parameters and • Patent: A Novel Route for the Inclusion of Metal Dopants in Silicon exchange couplings (GB0908254.6). EPR Hamiltonian • Thin film Tc above 77K Further funding • Optical control of exchange interactions Project is a platform for further funding, including EPSRC-NSFC grant in • EPR detection of biomolecules based on antibody/antigen interactions Foundations of Molecular Nanospintronics. • Magneto-optic phenomenology and EPR Hamiltonian for bioassay Engineering Application: new route to Science Application: molecular magnetic determine local order in organic solar cells wires and films from vapour Key issue: efficiency of organic devices strongly depends on Nanowires and films are essential for miniaturisation of spintronic device molecular orientation. However, diffraction cannot always be applied in and efficient spin transport through single crystal domains poorly crystallised systems. CuPc by Organic Vapour Phase Deposition Objectives: use spin resonance lineshapes and positions to determine Based on molecules in a 3-zone furnace and inert carrier gas wires with local order and orientation of dye molecules in test systems and apply new crystal structure, high flexibility and aspect ratios approaching CNTs to rationalisation of solar cells Top view of molecules on substrate g-factors observed CuPc on glass CuPc templated gperp Film B perp B parallel g// g g ( = 90°) ( = 0°) d // perp 001 On glass g┴ g// and g┴ 1 cm N2 400 nm 20 nm Templated g// g┴ 1.0 B “perpendicular” ( = 90°) B “parallel” ( = 90°) Magnetic properties show that wires have 0.8 Film on glass Templated CuPc:C mixed antiferromagnetic coupling, as rationalised by 60 0.6 beta 180 1 180 1 180 1 wire theoretical calculations. 170 170 170 160 0.8 160 0.8 160 0.8 0.4 150 150 150 0.6 0.6 0.6 140 140 140 Normalisedmagnetisation High orbital overlap along long axis should 130 130 130 0.4 0.4 0.4 0.2 120 120 120 ) ) ) 110 110 110 0.2 0.2 0.2 alpha mediate high anisotropic conductivity. 100 100 100 0.0 90 0 90 0 90 0 0 1 2 3 4 5 6 7 80 80 80 Orientation ( Orientation -0.2 Orientation ( Orientation Orientation ( Orientation -0.2 -0.2 70 70 70 m0H (Tesla) 60 60 60 -0.4 -0.4 -0.4 50 50 50 40 40 40 -0.6 -0.6 -0.6 30 30 30 20 -0.8 20 -0.8 20 -0.8 10 Increasing Tc using different transition metal derivatives 10 10 0 -1 0 -1 0 -1 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 Field (mT) Field (mT) Field (mT) Thin films grown using organic molecular beam deposition Unexpected benefit of BT project for energy sector: 8 0.8 1.5x10 1.0 0.6 0.4 Ferromagnetic film • molecular spins as an inexpensive in-line quality 0.2 0.0 8 -0.2 1.2x10 with Tc ~26 K 0.5 -0.4 -0.6 control tool to measure mol. orientation -0.8 -0.10 -0.08 -0.06 -0.04 -0.02 0.00 0.02 0.04 0.06 0.08 0.10 7 m H (Tesla) 0 9.0x10 0.0 • clustering and preferential orientation with 6.0x107 (Oe/emu) molecules perp to substrate in mixed CuPc:C60 -0.5 -1 3.0x107 • unfavourable orientation of molecules in mixed M normalised at 7T -1.0 0.0 solar cells, points to path for increased efficiency -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 0 20 40 60 80 m H (Tesla) Magnetisation 0.
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