Magnetic-field effects in defect-controlled ferromagnetic Ga_{1-x}Mn_xAs semiconductors

TL;DR

This study investigates how magnetic fields and Mn concentration affect magnetizations in Ga_{1-x}Mn_xAs semiconductors, highlighting the importance of precise doping control and reproducibility in experimental data.

Contribution

The paper introduces a mean-field model linking hole concentration to experimental Tc data, analyzing magnetization dependence on Mn doping and magnetic field.

Findings

Magnetization peaks sharply at certain Mn concentrations.

Applied magnetic fields increase the maximum magnetization.

Reproducibility issues in experimental Tc and p measurements are identified.

Abstract

We have studied the magnetic-field and concentration dependences of the magnetizations of the hole and Mn subsystems in diluted ferromagnetic semiconductor Ga_{1-x}Mn_xAs. A mean-field approximation to the hole-mediated interaction is used, in which the hole concentration p(x) is parametrized in terms of a fitting (of the hole effective mass and hole/local moment coupling) to experimental data on the Tc critical temperature. The dependence of the magnetizations with x, for a given temperature, presents a sharply peaked structure, with maxima increasing with applied magnetic field, which indicates that application to diluted-magnetic-semiconductor devices would require quality-control of the Mn-doping composition. We also compare various experimental data for Tc(x) and p(x) on different Ga_{1-x}Mn_xAs samples and stress the need of further detailed experimental work to assure that the experimental measurements are reproducible.