Generation of the second harmonic by spin waves propagating in microscopic stripes

We have studied experimentally the nonlinear frequency multiplication accompanying propagation of spin waves in microscopic Permalloy stripes. We find that a propagating spin wave efficiently generates another wave at the double frequency. By using an experimental technique with high spatial resolution, we show that the spatial distribution of the amplitude of the nonlinearly generated wave has a symmetry opposite that of the initial wave. We propose a qualitative model explaining this symmetry reversal.