Edge and corner skin effects of chirally coupled magnons characterized by a topological winding tuple

TL;DR

This paper explores how topology influences edge and corner localization of magnons in a non-Hermitian 2D nanomagnet array, revealing predictable skin effects characterized by a topological winding tuple, with implications for magnonic device design.

Contribution

It introduces a topological framework using a winding tuple to characterize edge and corner skin effects in a non-Hermitian magnonic system, demonstrating controllable localization by magnetic field orientation.

Findings

Magnon states localize at edges or corners based on topological winding numbers.

Varying magnetic field direction switches localization between edges and corners.

Topological characterization aids in designing future magnonic metasurfaces.

Abstract

We investigate a long-ranged coupled and non-Hermitian two-dimensional array of nanomagnets, fabricated on a thin magnetic substrate and subjected to an in-plane magnetic field. We predict topology-driven edge and corner skin effects of magnetic eigenmodes with the localization position at boundaries precisely characterized by a topological winding tuple $({\cal W}_1,{\cal W}_2)$. By varying the direction of the in-plane field, all magnon states pile up either at different edges of the array with $({\cal W}_1=\pm 1,{\cal W}_2=0)$ or $({\cal W}_1=0,{\cal W}_2=\pm 1)$, or at different corners characterized by $({\cal W}_1=\pm 1,{\cal W}_2=\pm 1)$. Exploiting the non-Hermitian topology is potentially helpful for designing useful magnonic metasurface in the future.