Spin-torque-induced magnetization dynamics in ferrimagnets based on Landau-Lifshitz-Bloch Equation

TL;DR

This paper develops a Landau-Lifshitz-Bloch based model to analyze spin-torque effects in ferrimagnets, capturing experimental phenomena and revealing unique precession-free switching dynamics and oscillation regions.

Contribution

It introduces a novel theoretical model based on the Landau-Lifshitz-Bloch equation for ferrimagnets, enabling systematic analysis of spin-torque effects beyond traditional models.

Findings

The model captures temperature dependence and spin torque peaks.

Switching in ferrimagnets is precession free, unlike ferromagnets.

An oscillation region exists at intermediate current densities.

Abstract

A theoretical model based on the Landau-Lifshitz-Bloch equation is developed to study the spin-torque effect in ferrimagnets. Experimental findings, such as the temperature dependence, the peak in spin torque, and the angular-momentum compensation, can be well captured. In contrast to the ferromagnet system, the switching trajectory in ferrimagnets is found to be precession free. The two sublattices are not always collinear, which produces large exchange field affecting the magnetization dynamics. The study of material composition shows the existence of an oscillation region at intermediate current density, induced by the nondeterministic switching. Compared to the Landau-Lifshitz-Gilbert model, our developed model based on the Landau-Lifshitz-Bloch equation enables the systematic study of spin-torque effect and the evaluation of ferrimagnet-based devices.