Two Modes of Magnetization Switching in a Simulated Iron Nanopillar in an Obliquely Oriented Field

TL;DR

This study uses micromagnetic simulations to reveal two distinct magnetization-switching modes in an iron nanopillar under an oblique magnetic field, highlighting the complexity of switching dynamics at finite temperature.

Contribution

It identifies and characterizes two competing switching modes—unstable decay and metastable decay—in a simulated iron nanopillar under specific conditions.

Findings

70% of switches involve unstable decay without a free-energy barrier

30% involve metastable decay crossing a free-energy barrier

Competition between modes can complicate magnetization switching applications

Abstract

Finite-temperature micromagnetics simulations are employed to study the magnetization-switching dynamics driven by a field applied at an angle to the long axis of an iron nanopillar. A bi-modal distribution in the switching times is observed, and evidence for two competing modes of magnetization-switching dynamics is presented. For the conditions studied here, temperature $T = 20$ K and the reversal field 3160 Oe at an angle of 75$^\circ$ to the long axis, approximately 70% of the switches involve unstable decay (no free-energy barrier) and 30% involve metastable decay (a free-energy barrier is crossed). The latter are indistinguishable from switches which are constrained to start at a metastable free-energy minimum. Competition between unstable and metastable decay could greatly complicate applications involving magnetization switches near the coercive field.