Edge localization of spin waves in antidot multilayers with perpendicular magnetic anisotropy

We study the spin-wave dynamics in nanoscale antidot lattices based on Co/Pd multilayers with perpendicularmagnetic anisotropy. Using time-resolved magneto-optical Kerr effect measurements we demonstrate that thevariation of the antidot shape introduces significant change in the spin-wave spectra, especially in the lowerfrequency range. By employing micromagnetic simulations we show that additional peaks observed in themeasured spectra are related to narrow shell regions around the antidots, where in-plane domain structures areformed. This is because the magnetic anisotropy in these regions is reduced due to the Ga(+)ion irradiation duringthe focused ion beam milling process of the antidot fabrication. The results point at possibilities for exploitationof localized spin waves in out-of-plane magnetized thin films, which are easily tunable and suitable for magnonicapplications.