Spin-wave propagation in metallic CoFe films determined by microfocused frequency-resolved magneto-optic Kerr effect.

We investigated the magnetization dynamics of a patterned Co$_{25}$Fe$_{75}$-based heterostructure with a novel optical measurement technique that we call microfocused frequency-resolved magneto optic Kerr effect ($mu$FR-MOKE). We measured the magnetic field dependence of the dynamical spin-wave susceptibility and recorded a spatial map of the spin-waves excited by a microwave antenna. We compare these results to those obtained on the same sample with the established microfocused Brillouin light scattering technique. With both techniques, we find a spin-wave propagation length of 5.6$mu$m at 10GHz. Furthermore, we measured the dispersion of the wavevector and the spin-wave propagation length as a function of the external magnetic field. These results are in good agreement with existing literature and with the employed Kalinkos-Slavin model.