Non-Hermitian Topological Magnonics

The damping of spin waves is affected by the current of the strip field. Chiral damping results in larger damping for spin waves propagating to the right and smaller damping for spin waves propagating to the left. This leads to more depletion for waves propagating to the right. However, there is no depletion for waves propagating to the left. This asymmetry has surprising effects on spin transport. In contrast to electrons, where transmission across a barrier is symmetric regardless of direction, spin waves exhibit different behavior depending on their direction of propagation.