Bias-dependent electrical spin generation in Fe3Si/GaAs : Consistent behavior in nonlocal and local spin valves and in the three-terminal configuration

Abstract

We study spin generation in lateral spin-valve structures consisting of ferromagnetic ${\mathrm{Fe}}_{3}\mathrm{Si}$ contacts on $n$-type GaAs transport channels. Different film-growth conditions are found to enable the comparison of ferromagnetic contacts with similar spin polarizations but different electrical characteristics. Strongly rectifying contacts are found to hinder the observation of spin-injection signals due to a strong bias dependence of the spin-generation efficiency. For contacts fabricated under optimized growth conditions, efficient spin generation enables the operation of nonlocal and local spin valves as well as the detection of spin signals in the three-terminal configuration. In all configurations, the observed signals exhibit a consistent bias-dependent spin generation and detection behavior which is explained by spin accumulation in the GaAs conduction band without the involvement of localized states.