Mean first-passage times for an ac-driven magnetic moment of a nanoparticle

TL;DR

This paper uses the backward Fokker-Planck equation to analyze how a rapidly rotating magnetic field affects the mean first-passage times and magnetic relaxation of nanoparticle magnetic moments, revealing equivalence to static field effects.

Contribution

It demonstrates that a rotating magnetic field perpendicular to the easy axis influences MFPTs similarly to a static field along the axis, providing new insights into nanoparticle magnetic relaxation.

Findings

Rotating magnetic fields govern MFPTs like static fields along the easy axis.

Features of magnetic relaxation are affected by the rotating field.

Net magnetization behavior is influenced by the rotating magnetic field.

Abstract

The two-dimensional backward Fokker-Planck equation is used to calculate the mean first-passage times (MFPTs) of the magnetic moment of a nanoparticle driven by a rotating magnetic field. It is shown that a magnetic field that is rapidly rotating in the plane {\it perpendicular} to the easy axis of the nanoparticle governs the MFPTs just in the same way as a static magnetic field that is applied {\it along} the easy axis. Within this framework, the features of the magnetic relaxation and net magnetization of systems composed of ferromagnetic nanoparticles arising from the action of the rotating field are revealed.