Spin dynamics in paramagnetic diluted magnetic semiconductors

TL;DR

This paper investigates the microscopic spin dynamics in paramagnetic diluted magnetic semiconductors using a Kondo lattice model and dynamical mean-field theory, revealing how magnetic scattering suppresses spin diffusion and its temperature dependence.

Contribution

It provides a theoretical framework connecting spin diffusion to Green functions in diluted magnetic semiconductors, incorporating disorder and temperature effects.

Findings

Magnetic scattering suppresses spin diffusion in the paramagnetic state.

Spin diffusion exhibits a $1/T$-like temperature dependence at low carrier concentrations.

The model offers insights into the spin dynamics across various parameters.

Abstract

Microscopic properties of low-energy spin dynamics in diluted magnetic semiconductor are addressed in a framework of the Kondo lattice model including random distribution of magnetic dopants. Based on the fluctuation-dissipation theorem, we derive an explicit dependence of the spin diffusion coefficient on the single-particle Green function which is directly evaluated by dynamical mean-field theory. In the paramagnetic state, the magnetic scattering has been manifested to suppress spin diffusion. In agreement with other ferromagnet systems, we also point out that the spin diffusion in diluted magnetic semiconductors at small carrier concentration displays a monotonic $1/T$-like temperature dependence. By investigating the spin diffusion coefficient on a wide range of the model parameters, the obtained results have provided a significant scenario to understand the spin dynamics in the paramagnetic diluted magnetic semiconductors.