Reversal of spin polarization in Fe/GaAs (001) driven by resonant surface states: First-principles calculations

TL;DR

This paper uses first-principles calculations to show that a resonant surface state at the Fe/GaAs interface can reverse electron spin polarization with voltage bias, explaining experimental spin injection and tunneling magnetoresistance data.

Contribution

It reveals the mechanism of spin polarization reversal driven by surface states at the Fe/GaAs interface using first-principles calculations.

Findings

Spin polarization reverses with bias voltage due to surface resonance.

Theoretical results align with recent experimental observations.

Resonant surface states significantly influence spin transport.

Abstract

A minority-spin resonant state at the Fe/GaAs(001) interface is predicted to reverse the spin polarization with voltage bias of electrons transmitted across this interface. Using a Green's function approach within the local spin density approximation we calculate spin-dependent current in a Fe/GaAs/Cu tunnel junction as a function of applied bias voltage. We find a change in sign of the spin polarization of tunneling electrons with bias voltage due to the interface minority-spin resonance. This result explains recent experimental data on spin injection in Fe/GaAs contacts and on tunneling magnetoresistance in Fe/GaAs/Fe magnetic tunnel junctions.