Chapter 8: Magnetic Normal Modes of Nanopatterned Magnets Investigated by Both Wavevector- and Space-Resolved Brillouin Light Scattering Spectroscopy

Results from combined wavevector- and space-resolved Brillouin light scattering (BLS) investigation of the magnetic eigenmodes of nanopatterned magnetic elements and arrays of elements are presented and discussed. Two classes of elements are considered: Elliptical nanorings in the vortex and onion ground states, and uniformly magnetized rectangular elements arranged in close packed arrays in square “artificial spin ice” (ASI) geometries. A careful comparison of the calculated frequency and profiles, as well as of the scattering cross-section, of magnetic modes with the experimental data, allows the identification of the character of the different modes in terms of spatial symmetry and localization. Micromagnetics is used to analyze and identify possible modes that are active in the scattering process. Spatially resolved light scattering is used in the case of elliptical rings to create two-dimensional space-resolved maps of the mode intensity over the ring surface.