On the nature of the spin-polarized hole states in a quasi-two-dimensional GaMnAs ferromagnetic layer

TL;DR

This study uses a self-consistent model to analyze how Mn concentration and hole density influence the localization and spin polarization of holes in GaMnAs layers, shedding light on ferromagnetism mechanisms.

Contribution

It provides a detailed theoretical analysis of the nature of spin-polarized hole states in GaMnAs, linking magnetic order with state localization and spin polarization.

Findings

Increased magnetic order correlates with delocalization of certain hole states.

Spin-polarized extended states can be anti-aligned with Mn magnetization.

Results support high-temperature ferromagnetism in thin films.

Abstract

A self-consistent calculation of the density of states and the spectral density function is performed in a two-dimensional spin-polarized hole system based on a multiple-scattering approximation. Using parameters corresponding to GaMnAs thin layers, a wide range of Mn concentrations and hole densities have been explored to understand the nature, localized or extended, of the spin-polarized holes at the Fermi level for several values of the average magnetization of the Mn ystem. We show that, for a certain interval of Mn and hole densities, an increase on the magnetic order of the Mn ions come together with a change of the nature of the states at the Fermi level. This fact provides a delocalization of spin-polarized extended states anti-aligned to the average Mn magnetization, and a higher spin-polarization of the hole gas. These results are consistent with the occurrence of ferromagnetism with relatively high transition temperatures observed in some thin film samples and multilayered structures of this material.