Controlled interconversion of quantized spin wave modes via local magnetic fields

In the emerging field of magnonics, spin waves are considered for information processing and transmission at high frequencies. Accordingly, the manipulation of propagating spin waves in nanostructured waveguides for novel functionality has attracted increased attention. Excitations with uniform magnetic fields in such waveguides favor symmetric spin-wave modes with odd quantization numbers. Interference between multiple odd spin-wave modes leads to a periodic self-focusing effect of the propagating spin waves. In this work we demonstrate how antisymmetric spin-wave modes with even quantization numbers can be induced by local magnetic fields in a well-controlled fashion. The resulting interference patterns are discussed within an analytical model and experimentally demonstrated using microfocused Brillouin light scattering.