Softening of Spin-Wave Stiffness near the Ferromagnetic Phase Transition in Diluted Magnetic Semiconductors

TL;DR

This paper investigates how the spin-wave stiffness in diluted magnetic semiconductors decreases sharply near the ferromagnetic transition temperature, using a self-consistent Green's function approach that captures spatial and temperature fluctuations.

Contribution

It introduces a self-consistent Green's function method to study temperature effects on spin-wave stiffness, surpassing traditional mean-field theories.

Findings

Spin-wave stiffness dramatically softens near the critical temperature.

The approach explains sharp drops in magnetization in diffusive samples.

Green's function method captures spatial and temperature fluctuations.

Abstract

Employing the self-consistent Green's function approach, we studied the temperature dependence of the spin-wave stiffness in diluted magnetic semiconductors. Note that the Green's function approach includes the spatial and temperature fluctuations simultaneously which was not possible within conventional Weiss mean-field theory. It is rather interesting that we found the stiffness becomes dramatically softened as the critical temperature is approached, which seems to explain the mysterious sharp drop of magnetization curves in samples within diffusive regime.