Static and dynamic magnetic properties of Ni80 Fe20 square antidot arrays

Abstract

We have investigated both static and dynamic magnetic properties of square antidot arrays in a ferromagnetic thin-film structure of Au (2 nm)/ Ni80 Fe20 (27.6 nm) on a SiO2 500 nm/Si substrate using magneto-optic Kerr effect magnetometry, Brillouin light scattering (BLS), and micromagnetic simulations. The antidot patterns were 1 µm square holes arranged in two separate square lattices of dot separations d=0.6 µm and 1.0 µm. The introduction of antidots induced an in-plane fourfold magnetic anisotropy with hard axes on the two nearest-antidot-neighbor directions. The coercive field, Hc, was increased by the presence of antidots. Fixed-frequency modes were observed in spin-wave dispersion relations in remanent spin configurations. These modes correspond to spin-wave confinement by antidot edges, which were seen as a series of nodal lines parallel to the edges in simulated spin-wave mode spatial mappings. Domains in remanent states, some of which were responsible for the existence of dipole-exchange backward volume modes seen in BLS spectra, were also found to confine spin waves in simulations. © 2009 The American Physical Society.