Nonmonotonic bias dependence of local spin accumulation signals in ferromagnet/semiconductor lateral spin-valve devices

TL;DR

This paper reports on the unusual nonmonotonic bias dependence of local spin signals in ferromagnet/semiconductor devices, including sign inversion, explained by interface spin polarization reduction and other effects.

Contribution

It reveals the nonmonotonic bias dependence and sign inversion of local spin signals in FM/SC devices, highlighting the roles of interface polarization and spin drift.

Findings

Nonmonotonic bias dependence of spin signals observed

Sign inversion of spin accumulation signals detected

Influence of interface polarization reduction and spin drift discussed

Abstract

We find extraordinary behavior of the local two-terminal spin accumulation signals in ferromagnet (FM)/semiconductor (SC) lateral spin-valve devices. With respect to the bias voltage applied between two FM/SC Schottky tunnel contacts, the local spin-accumulation signal can show nonmonotonic variations, including a sign inversion. A part of the nonmonotonic features can be understood qualitatively by considering the rapid reduction in the spin polarization of the FM/SC interfaces with increasing bias voltage. In addition to the sign inversion of the FM/SC interface spin polarization, the influence of the spin-drift effect in the SC layer and the nonlinear electrical spin conversion at a biased FM/SC contact are discussed.