Low-field FMR studies of magnetic confinement effects in patterned ferromagnetic thin films

We have performed broad-band (10 MHz-20 GHz) and tuned cavity (9.7 GHz) ferromagnetic resonance measurements on permalloy thin films patterned with square lattices of circular, square and diamond-shaped antidots of various sizes and separations. We observe remarkably reproducible mode structures in the low-frequency, hysteretic regime in which various domain wall patterns and unsaturated magnetization textures exist and are strongly affected by the geometry of the antidot lattice. The field, frequency and angular dependences of the observed modes (some of which have not been previously observed) are generally in good agreement with our micromagnetic simulations.