Towards half-metallic interfaces: the Co$_2$CrAl/InP contacts

TL;DR

This paper investigates mechanisms to maintain high spin-polarization at Co2CrAl/InP interfaces, crucial for spintronic devices, by analyzing how interface composition affects magnetic moments and spin-polarization despite loss of half-metallicity.

Contribution

It identifies specific interface configurations and mechanisms that preserve high spin-polarization at Co2CrAl/InP interfaces, despite the loss of half-metallicity.

Findings

CrAl termination enhances spin-polarization via Cr moment increase

Co/In or Co/P interfaces show reduced Co spin moments but maintain high polarization

High spin-polarization (>80%) achieved despite loss of half-metallicity

Abstract

Although the interest on half-metallic Heusler alloys, susceptible to be used in spintronic applications, has considerably grown, their interfaces with semiconductors show very low spin-polarization. I identify mechanisms which can keep the high spin-polarization at the interface (more than 80% of the electrons at the Fermi level are of majority spin) although the half-metallicity is lost. The large enhancement of the Cr moment at the interface between a CrAl terminated Co$_2$CrAl(001) spacer and the InP(001) semiconductor weakens the effect of the interface states resulting in this high spin-polarization. On the other hand the Co$_2$CrAl/InP interfaces made up by a Co layer and either an In or a P one show a severe decrease of the Co spin moment but Cr in the subinterface layer is bulklike and the resulting spin-polarization is similar to the CrAl-based interfaces.