Non-Hermitian Topological Magnonics

When the thickness of the ferromagnet is larger than the critical value dF zero, the exceptional point always appears in some propagation directions. This is the persistent emergence of a nodal magnon-polariton in the heterostructure. In the next part, I will introduce the concept as an example of the non-Hermitian skin effect of magnons. The non-Hermitian effect can be easily understood by the high-dimensional model.