Dynamics at finite temperatures of single-domain particles driven by rotating magnetic fields

Recent studies show that the magnetization of nanoparticles with uniaxial anisotropy can be reversed by rotating magnetic fields applied perpendicular to the easy axis. In this contribution the details of this switching process is worked out in detail by solving the Fokker-Planck equation describing the dynamics of the magnetic moment at finite temperatures numerically. The dependence of the induced magnetization due to the rotating field on temperature as well as on frequency and amplitude of the driving field is studied. Of particular interest is the time for switching the magnetization between metastable states. This time is analyzed in detail and it is shown in particular that it increases dramatically with driving frequency. The numerical method developed in this paper is applicable to many other problems in magnetism on the nanoscale.