Mode conversion by symmetry breaking of propagating spin waves

We study spin-wave transport in a microstructured Ni81Fe19 waveguide exhibiting broken translational symmetry. We observe the conversion of a beam profile composed of symmetric spin-wave width modes with odd numbers of antinodes n = 1, 3,… into a mixed set of symmetric and asymmetric modes. Due to the spatial homogeneity of the exciting field along the used microstrip antenna, quantized spin-wave modes with an even number n of antinodes across the stripe’s width cannot be directly excited. We show that a break in translational symmetry may result in a partial conversion of even spin-wave waveguide modes.