Spectral intensities and frequencies of spin waves in ferromagnetic cylinders: Application to nickel nanowires

Abstract

The theory for dipole-exchange spin waves in cylindrical ferromagnetic nanowires, as developed in a previous paper, is extended to include spectral intensities, arbitrary orientation of external magnetic field, and effects of single-ion anisotropy. This allows applications to be made to the nickel nanowires studied experimentally. The dependences of the spin-wave frequencies on the nanowire radius, wave vector, and magnetic field are investigated, and the spatial distribution of the eigenmodes are evaluated to analyze their localization. The spectral intensities are calculated within a Green's function formalism, giving a good insight into data from Brillouin light scattering. The spin-wave frequencies obtained in the case of zero field are compared to the experimental results for nickel, and to results deduced from macroscopic theory under conditions of small surface pinning. Also when the magnetic field is perpendicular to the wire axis, making the magnetization nonuniform, our results provide a good description of the experimental behavior.