Observation of spin-wave propagation in permalloy microstripes

We report on the propagation of spin waves in permalloy microstripes. By means of scanning Kerr microscopy combined with continuous microwave excitation, we detect the time evolution of spin-wave interference patterns in an external magnetic field. Assuming transverse spin-wave quantization we can directly measure the amplitude, phase velocity and damping for the corresponding transversal wave mode numbers m. We find that the spin-wave interference pattern is dominated by m=0 and m=2 with phase velocities v_0=71 km/s and v_2=47 km/s, respectively.