Studies of spin related processes in fullerene C₆₀ devices

We have investigated spin related processes in fullerene C₆₀ devices using several experimental techniques, which include magnetic field effect of photocurrent and electroluminescence in C₆₀-based diodes; spin polarized carrier injection in C₆₀-based spin-valves; and pure spin current generation in NiFe/C₆₀/Pt trilayer devices. We found that the 'curvature-related spin orbit coupling' in C₆₀ plays a dominant role in the obtained spin-related phenomena. The measured magneto-photocurrent and magneto-electroluminescence responses in C₆₀ diodes are dominated by the difference in the g-values of hole and electron polarons in the fullerene molecules. We also obtained giant magneto-resistance of ∼10% at 10 K in C₆₀ spin-valve devices, where spin polarized holes are injected into the C₆₀ interlayer. In addition, using the technique of spin-pumping in NiFe/C₆₀/Pt trilayer devices with various C₆₀ interlayer thicknesses we determined the spin diffusion length in C₆₀ films to be 13 ± 2 nm at room temperature.