Spatial profile of spin excitations in multilayered rectangular nanodots studied by microfocused Brillouin light scattering

An array of multilayered rectangular NiFe/Cu/NiFe dots (lateral dimensions 720 × 430 nm, thicknesses 10/10/10 nm) has been fabricated by electron-beam lithography. The magnetization reversal process has been studied by the magneto-optical Kerr effect, showing that the dipolar coupling between the two magnetic layers plays an important role and competes with shape anisotropy, determining the characteristic profile of the hysteresis curve. Moreover, both conventional and microfocused Brillouin light scattering have been exploited to study the eigenmodes spectrum in the gigahertz range, achieving a direct visualization of the spatial profile of the different modes. The results are in good agreement with both the modes frequency and the spatial profiles obtained by micromagnetic simulations.