Confined dynamic excitations in structured magnetic media

High-quality arrays of submicrometer size magnetic rectangular elements and stripes are considered to be a prototype of the next generation magnetic memory. Spin waves are the fundamental dynamic eigenmodes of a magnetic system and spin wave frequencies determine characteristic temporal parameters of the system. This presentation covers the recent results obtained on confined spin wave excitations in arrays of magnetic elements using Brillouin light scattering spectroscopy. Quantization of spin waves in axially magnetized stripes leads to appearance of gaps in the spin wave mode spectrum. The quantized spin wave frequencies are determined by the stripe width and by the boundary conditions at the lateral edges of the stripe. The confinement effects are even more dramatic for rectangular magnetic elements or magnetic stripes magnetized perpendicular to their axis. In both cases, the internal magnetic field is highly inhomogeneous. The inhomogeneity creates potential wells for spin waves near the edges of the elements, causing a localization of low frequency magnetic excitations in the well.