Comparison of electrical and optical detection of spin injection in L1₀-FePt/MgO/GaAs hybrid structures

We have investigated comparative experiments for spin injection into semiconductor in an ordered L1₀-FePt/MgO/n-GaAs hybrid structure using electrical and optical detection methods. Spatial-resolved Kerr rotation microscope image clearly demonstrates accumulation of perpendicularly oriented spins in an n-GaAs channel at zero magnetic field. On the other hand, electrical three-terminal Hanle measurement shows shorter spin lifetime than that of the optical measurement. It suggests that the spin lifetime obtained from three-terminal Hanle method originates from spins at the MgO/GaAs interface but not in the bulk GaAs channel. (paper)