# 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.

## Key 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.