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Electrical spin injection from ferromagnet into an InAs heterostructures through MgO tunnel barrier

We have investigated electrical spin injection from Ni81Fe19 into an InAs quantum well through MgO tunneling barrier for potential application to InAs-based spin field effect transistor. Injected spin polarized current were detected in both nonlocal and local spin valve set-ups and the spin diffusion length and spin injection efficiency were analyzed. The spin diffusion length was estimated to be 1.6 μm in nonlocal set-up at 1.4 K. The spin polarization of Ni81Fe19/MgO/InAs as-deposited sample was relealed to be 6.9 %, while increased spin polarization of 8.9 % was observed by additional thermal treatment.