Forced response and dynamic hysteresis of magnetic nanoparticles with mixed uniaxial and cubic anisotropy in superimposed strong ac and dc bias fields

摘要

The stationary response of ferromagnetic nanoparticles with mixed uniaxial and cubic anisotropy to superimposed external ac and dc bias fields of arbitrary strength is investigated using Brown's continuous diffusion of orientations model [W. F. Brown Jr., Phys. Rev. 130, 1677 (1963)]. The susceptibility and dynamic magnetic hysteresis (DMH) loops of an individual nanoparticle are calculated in extensive ranges of the superimposed fields, their orientation, damping, temperature, and specific mixed anisotropy parameter. The DMH loops and nonlinear dynamic susceptibility strongly depend on the dc and ac field strengths, the polar angle between the easy axis of the particle and the external field vectors, as well as the temperature and damping, simultaneously displaying a marked dependence on the mixed anisotropy parameter.