Magnetization dynamics at elevated temperatures

TL;DR

This paper introduces a unified quantum kinetic equation for magnetization dynamics applicable across a wide temperature range, bridging low-temperature and high-temperature models, and including thermal fluctuations.

Contribution

It presents a novel equation that unifies magnetization dynamics models across all temperatures, incorporating stochastic fields for high-temperature fluctuations.

Findings

Equation reduces to Landau-Lifshitz at low T

Equation reduces to Bloch at high T

Includes stochastic fields for thermal fluctuations

Abstract

By using the quantum kinetic approach with the instantaneous local equilibrium approximation, we propose an equation that is capable of addressing magnetization dynamics for a wide range of temperatures. The equation reduces to the Landau-Lifshitz equation at low temperatures and to the paramagnetic Bloch equation at high temperatures. Near the Curie temperature, the magnetization reversal and dynamics depend on both transverse and longitudinal relaxations. We further include the stochastic fields in the dynamic equation in order to take into account fluctuation at high temperatures. Our proposed equation may be broadly used for modeling laser pump-probe experiments and heat assisted magnetic recording.