Bias-induced destruction of ferromagnetism and disorder effects in GaMnAs heterostructures

TL;DR

This study models how bias voltage and disorder affect ferromagnetism and spin polarization in GaMnAs heterostructures, revealing that resonance conditions can suppress magnetic order and that disorder impacts electronic and magnetic properties.

Contribution

It introduces a self-consistent Green's function approach to analyze bias-induced magnetic destruction and disorder effects in GaMnAs heterostructures.

Findings

Resonance peaks are highly sensitive to disorder.

Ferromagnetic order can be destroyed near resonance.

Disorder affects spin polarization and I-V characteristics.

Abstract

The magneto-electric properties of resonant tunneling double barrier structures using GaMnAs for the quantum well is investigated within a self-consistent Green's function approach and a tight-binding electronic structure model. The magnetic state of the well is determined self-consistently by the tunneling current which controls the hole spin density and, hence, the degree of exchange splitting of the subbands inside the well. Prompted by recent experiments we compare model systems of increasing defect concentration (substitutional disorder) regarding their I-V curve, magnetic state, and spin polarization. We predict that, near resonance, the ferromagnetic order which may be present at zero bias in the GaMnAs well tends to be destroyed. Resonance peaks are found to be more sensitive to disorder than ferromagnetic ordering and spin polarization of the steady-state current.