Damping-like spin-orbit-torque-induced magnetization dynamics in ferrimagnets based on Landau-Lifshitz-Bloch equation

Abstract

© 2018 Author(s). A theoretical model based on the Landau-Lifshitz-Bloch equation is developed to study the effect of damping-like spin-orbit torque in ferrimagnets, which can capture many experimental findings. For example, the sample changes from Gd to FeCo dominate by increasing temperature, the damping-like spin-orbit torque has a peak at the magnetization compensation temperature, and angular-momentum compensation temperature increases as a function of Gd concentration. 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 produce a 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 the spin-torque effect and the evaluation of ferrimagnet-based devices.