Spin Dependent Tunneling in FM|semiconductor|FM structures

TL;DR

This paper demonstrates how standard band structure calculations can elucidate spin-injection mechanisms at ferromagnet/semiconductor interfaces, aiding in the design of materials with high tunneling magnetoresistance.

Contribution

It introduces a method using ab-initio calculations to analyze spin-dependent tunneling and screen material combinations for improved TMR in FM|semiconductor structures.

Findings

Fe wave functions decay differently in GaAs and ZnSe based on symmetry.

Band structure codes can effectively model spin-injection at interfaces.

Material screening can optimize TMR properties.

Abstract

Here we show that ordinary band structure codes can be used to understand the mechanisms of coherent spin-injection at interfaces between ferromagnets and semiconductors. This approach allows the screening of different material combinations for properties useful for obtaining high tunneling magnetoresistance (TMR). We used the Vienna Ab-initio Simulation Code (VASP) to calculate the wave function character of each band in periodic epitaxial Fe(100)|GaAs(100) and Fe(100)|ZnSe(100) structures. It is shown that Fe wave functions of different symmetry near Fermi energy decay differently in the GaAs and ZnSe.