title: Curvature-enhanced Spin-orbit Coupling and Spinterface Effect in Fullerene-based Spin Valves.
abstract: We investigated curvature-enhanced spin-orbit coupling (SOC) and spinterface effect in carbon-based organic spin valves (OSVs) using buckyball C60 and C70 molecules. Since the naturally abundant (12)C has spinless nuclear, the materials have negligible hyperfine interaction (HFI) and the same intrinsic SOC, but different curvature SOC due to their distinct curvatures. We fitted the thickness dependence of magnetoresistance (MR) in OSVs at various temperatures using the modified Jullière equation. We found that the spin diffusion length in the C70 film is above 120 nm, clearly longer than that in C60 film at all temperatures. The effective SOC ratio of the C70 film to the C60 film was estimated to be about 0.8. This was confirmed by the magneto-electroluminescence (MEL) measurement in fullerene-based light emitting diodes (LED). Next, the effective spin polarization in C70-based OSVs is smaller than that in C60-based OSVs implying that they have different spinterface effect. First principle calculation study shows that the spin polarization of the dz(2) orbital electrons of Co atoms contacted with C60 is larger causing better effective spin polarization at the interface.
authors.affiliation: Physics and Astronomy Department, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Shiheng
authors.initials: S
authors.lastname: Liang
authors.affiliation: Physics and Astronomy Department, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Rugang
authors.initials: R
authors.lastname: Geng
authors.affiliation: State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Baishun
authors.initials: B
authors.lastname: Yang
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, University of Science and Technology of China, Hefei 230026, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Wenbo
authors.initials: W
authors.lastname: Zhao
authors.affiliation: Physics and Astronomy Department, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Ram
authors.initials: R
authors.lastname: Chandra Subedi
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, University of Science and Technology of China, Hefei 230026, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Xiufeng
authors.initials: X
authors.lastname: Han
authors.affiliation: Physics and Astronomy Department, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Tho Duc
authors.initials: TD
authors.lastname: Nguyen