Magnetic dynamics with spin transfer torques near the Curie temperature

TL;DR

This paper investigates how spin transfer torques influence magnetic dynamics near the Curie temperature using atomistic simulations and a mean field theory, revealing significant longitudinal effects on magnetization.

Contribution

It introduces a combined atomistic simulation and mean field approach to study thermal fluctuation effects on spin transfer torques near T_C.

Findings

Longitudinal spin transfer effects are significant near T_C.

Magnetization changes can be accurately modeled by a Landau-Lifshitz-Bloch + Slonczewski equation.

Simulation results align with mean field theory predictions.

Abstract

We use atomistic stochastic Landau-Lifshitz-Slonczewski simulations to study the interaction between large thermal fluctuations and spin transfer torques in the magnetic layers of spin valves. At temperatures near the Curie temperature $T_{\rm C}$, spin currents measurably change the size of the magnetization (i.e. there is a {\it longitudinal} spin transfer effect). The change in magnetization of the free magnetic layer in a spin valve modifies the temperature dependence of the applied field-applied current phase diagram for temperatures near $T_{\rm C}$. These atomistic simulations can be accurately described by a Landau-Lifshitz-Bloch + Slonczewski equation, which is a thermally averaged mean field theory. Both the simulation and the mean field theory show that a longitudinal spin transfer effect can be a substantial fraction of the magnetization close to $T_{\rm C}$.