Impurity relaxation mechanism for dynamic magnetization reversal in a single domain grain

TL;DR

This paper investigates how impurity relaxation mechanisms influence the dynamic magnetization reversal in single domain grains, deriving equations that connect microscopic impurity processes to macroscopic magnetization behavior.

Contribution

It introduces a model linking impurity relaxation mechanisms to magnetization dynamics, deriving equations that incorporate microscopic impurity effects into the Landau-Lifshitz framework.

Findings

Impurity relaxation rates significantly affect magnetization damping.

Derived equations connect microscopic impurity processes with macroscopic magnetization dynamics.

Damping parameter can be calculated from impurity relaxation mechanisms.

Abstract

The interaction of coherent magnetization rotation with a system of two-level impurities is studied. Two different, but not contradictory mechanisms, the `slow-relaxing ion' and the `fast-relaxing ion' are utilized to derive a system of integro-differential equations for the magnetization. In the case that the impurity relaxation rate is much greater than the magnetization precession frequency, these equations can be written in the form of the Landau-Lifshitz equation with damping. Thus the damping parameter can be directly calculated from these microscopic impurity relaxation processes.