Electrical spin injection in Ni81Fe19/Al/Ni81Fe19 with double tunnel junctions

Spin polarized electrons injected from ferromagnets (F) into non-magnetic materials (N) create nonequilibrium spin accumulation in N. This spin accumulation can be detected as a voltage signal by using non-local transport measurement for a F/N/F structure with tunnel barriers. We performed non-local measurements for Ni81Fe19/Al/Ni81Fe19 with double tunnel junctions to confirm the spin accumulation. The spin-dependent signals ΔR=ΔV/I as large as 35mΩ were obtained at 10 K and decreased with increasing temperature due to the reduction of the spin diffusion length.