Non-Hermitian Topological Magnonics

Finally, I will briefly mention the anomalous transport enabled by Cato damping, which is a source of non-Hermitian Hamiltonians. When a normal metal is placed near spin waves, the eddy current driven by the dial field from the spin waves causes damping. In a measurement, the NV center in the diamond observed the propagation of the spin wave beneath the normal metal (yellow region) and found that the damping below the normal metal is larger than outside of it. Recently, it was discovered that this damping is chiral.