Interlayer and interfacial exchange coupling in ferromagnetic metal/semiconductor heterostructures

TL;DR

This paper investigates the exchange coupling mechanisms in ferromagnetic metal/semiconductor heterostructures, revealing how layer thickness, composition, and spacer layers influence magnetic interactions and bias fields.

Contribution

It introduces a comprehensive exchange spring model for MnAs/GaMnAs bilayers and provides evidence for hole-mediated interlayer exchange coupling in trilayers.

Findings

Exchange bias varies with layer thickness and composition.

Hole-mediated interlayer exchange coupling observed.

Dependence of exchange bias on spacer layer thickness.

Abstract

We describe a systematic study of the exchange coupling between a magnetically hard metallic ferromagnet (MnAs) and a magnetically soft ferromagnetic semiconductor (GaMnAs) in bilayer and trilayer heterostructures. An exchange spring model of MnAs/GaMnAs bilayers accounts for the variation of the exchange bias field with layer thickness and composition. We also present evidence for hole-mediated interlayer exchange coupling in MnAs/p-GaAs/\GaMnAs trilayers and study the dependence of the exchange bias field on the thickness of the spacer layer.