Transition state theory characterizes thin film macrospin dynamics driven by an oscillatory magnetic field: Inertial effects

TL;DR

This paper explores how inertial effects influence the magnetization switching in ferromagnetic thin films under oscillatory magnetic fields, revealing resonance phenomena and the importance of relaxation rates using transition state theory.

Contribution

It extends the Landau-Lifshitz-Gilbert model to include inertia and applies transition state theory to analyze magnetization switching rates under periodic driving.

Findings

Magnetization exhibits resonance-like behavior under specific driving conditions.

Switching rates are strongly affected by the system's relaxation rate.

Inertial effects significantly influence the switching dynamics.

Abstract

Understanding the magnetization switching process in ferromagnetic thin films is essential for many technological applications. We investigate the effects of periodic driving via magnetic fields on a macrospin system under explicit consideration of inertial dynamics. This is usually achieved by extending the Landau-Lifshitz-Gilbert equation with a term including the second time derivative of the magnetization. The dynamics of the magnetization switching can then be characterized by its switching rate. We apply methods from transition state theory for driven systems to resolve the rate of magnetization switching in this general case. In doing so, we find that magnetization exhibits resonance-like behavior under certain driving conditions, and it can be affected strongly by the system's relaxation rate.