Switching properties of ferromagnetic nanoparticles driven by a circularly polarizedmagnetic field

Abstract

We present a comprehensive study of the magnetization switching of a uniaxialnanoparticle driven by a circularly polarized magnetic field rotated in the planeperpendicular to the easy axis. The conditions for the existence of the uniform andnon-uniform precessions of the nanoparticle magnetic moment are derived. In addition, thedifferences between switchings via uniform and non-uniform precession are determined, andthe essential role of field polarization is demonstrated. The dependence of the switchingtime on the field amplitude and frequency are calculated numerically. We show that apermanent magnetic field can reduce the amplitude and frequency of the switchingrotating field, and that the combined action of these fields is characterized by anextremely strong dependence of the switching time on the field parameters. Wealso demonstrate that the transition process caused by an external magneticfield pulse can decrease the switching amplitude in comparison with the valuepredicted from analysis of the stability criterion. We discuss the advantages ofswitching the magnetization by means of the action of a rotating field over themagnetization switching using a steady field applied perpendicular to the easy axis.