Switching speed distribution of spin-torque-induced magnetic reversal

TL;DR

This paper analyzes the distribution of switching speeds in spin-torque-induced magnetic reversal using the Fokker-Planck equation, providing analytical and numerical insights into the eigenvalues that govern the slowest switching events.

Contribution

It introduces a method to evaluate the switching probability distribution by calculating the lowest eigenvalue of the Fokker-Planck equation, validating previous models under certain conditions.

Findings

Eigenvalue $$ accurately determines slowest switching times

Analytical and numerical methods agree in specific limits

Previous thermally distributed initial state model is justified in some cases

Abstract

The switching probability of a single-domain ferromagnet under spin-current excitation is evaluated using the Fokker-Planck equation(FPE). In the case of uniaxial anisotropy, the FPE reduces to an ordinary differential equation in which the lowest eigenvalue $\lambda_1$ determines the slowest switching events. We have calculated $\lambda_1$ by using both analytical and numerical methods. It is found that the previous model based on thermally distributed initial magnetization states \cite{Sun1} can be accurately justified in some useful limiting conditions.