Evidence of an embedded vortex translation mode in flake-shaped ferromagnetic particle composites

Abstract

A low-frequency resonance (sub-GHz) is observed in microwave permeability spectra of anisotropic flake-shaped ferromagnetic particle composites. The resonance frequency of this peak increases linearly with the saturation magnetization of flakes, their aspect ratio, and the amplitude of a perpendicular static magnetic field. In addition, this resonance becomes extinct for a perpendicular RF exciting magnetic field. These experimental features are reproduced by an analytical model of vortex dynamics which militates in favor of an assignment of this low-frequency signal as an embedded vortex translation mode within a multidomain magnetic structure.