Mode conversion by symmetry breaking of propagating spin waves

TL;DR

This paper investigates how breaking translational symmetry in a Ni81Fe19 waveguide causes spin-wave modes to convert between symmetric and asymmetric profiles, revealing mode mixing effects.

Contribution

It demonstrates that symmetry breaking enables partial conversion of spin-wave modes that cannot be directly excited due to uniform excitation fields.

Findings

Symmetry breaking induces mode conversion in spin waves.

Even modes cannot be directly excited by uniform fields.

Partial conversion of modes observed due to symmetry breaking.

Abstract

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