Spin-wave dynamics in perpendicularly magnetized antidot multilayers.

Abstract

Using all-optical time-resolved magneto-optical Kerr effect (TR-MOKE) measurements we demonstrate an efficient modulation of the spin-wave (SW) dynamics via the bias magnetic field orientation around nanoscale diamond shaped antidots that are arranged on a square lattice within a [Co(0.75)/Pd(0.9)]8multilayer with perpendicular magnetic anisotropy (PMA). Micromagnetic modelling of the experimental results reveals that the SW modes in the lower frequency regime are related to narrow shell regions around the antidots, where in-plane domain structures are formed due to the reduced magnetic anisotropy, caused by Ga+ion irradiation during the focused ion beam milling process of antidot fabrication. The in-plane direction of the shell magnetization undergoes a striking change with magnetic field orientation, leading to the sharp variation of the edge localized (shell) SW modes. Nevertheless, the coupling between such edge localized and bulk SWs for different orientations of bias field in PMA systems give rise to interesting Physics and attests to new prospects for developing energy efficient and hybrid-system-based next-generation nanoscale magnonic devices.&#xD.