Temperature-dependent magnetization in diluted magnetic semiconductors

TL;DR

This paper models magnetization in diluted magnetic semiconductors using various theoretical approaches, showing good agreement with experimental data across different material regimes and emphasizing the role of carrier density.

Contribution

It provides a comprehensive theoretical analysis of magnetization in diluted magnetic semiconductors, comparing mean-field and percolation theories with experimental results.

Findings

Mean-field theory aligns with itinerant systems like GaMnAs.

Percolation theory matches insulating materials like GeMn.

Carrier density critically influences magnetization behavior.

Abstract

We calculate magnetization in magnetically doped semiconductors assuming a local exchange model of carrier-mediated ferromagnetic mechanism and using a number of complementary theoretical approaches. In general, we find that the results of our mean-field calculations, particularly the dynamical mean field theory results, give excellent qualitative agreement with the experimentally observed magnetization in systems with itinerant charge carriers, such as Ga_{1-x}Mn_xAs with 0.03 < x < 0.07, whereas our percolation-theory-based calculations agree well with the existing data in strongly insulating materials, such as Ge_{1-x}Mn_x. We comment on the issue of non-mean-field like magnetization curves and on the observed incomplete saturation magnetization values in diluted magnetic semiconductors from our theoretical perspective. In agreement with experimental observations, we find the carrier density to be the crucial parameter determining the magnetization behavior. Our calculated dependence of magnetization on external magnetic field is also in excellent agreement with the existing experimental data.