Ferromagnetic resonance investigations of spin waves in Fe-Ni multilayers

Abstract

The standing spin-wave resonance (SSWR) at 9.2 GHz has been investigated in a multilayer structure composed of alternating layers of Ni and Fe for the as-prepared sample and at different annealing temperatures between 420 and 570 K. Changes of the resonance field and of the intensity of spin-wave modes with annealing temperature indicate the excitation of a surface mode in the as-prepared sample. Heating of the multilayer above 520 K leads to a spin-wave spectrum which exhibits a behavior corresponding to an alloy with comparable chemical composition. The SSWR fields show a quadratic dependence of the wave number of the spin waves at all annealing temperatures but a drastic change of surface spin pinning with increasing temperature.