Influence of roughness on the magnetostatic modes of ferromagnetic nano-wires

Abstract

Magnetic nano-entities in their own or as parts of artificial structures have recently been the subject of a large research effort. In order to understand their dynamic behavior, in particular their microwave response as well their spin-wave modes are of great interest. The latter subject is fairly understood in the bulk and for ferromagnetic thin films, but is under development for nano-structures. One aspect of interest is the influence of roughness on the spin-wave modes of these nano-entities. In this work this is studied in the magnetostatic approximation for nano-wires of elliptical cross section that have rough surfaces. The method is based on a perturbation treatment of extinction equations. The conclusion is that to first order surface roughness may well account for experimental frequency shifts of spin modes of nano-wires.