Tunable topological magnon phases in layered ferrimagnets
Jie Liu, Lin Wang, Ka Shen
Abstract
The introduction of effective spin-orbit couplings into magnon systems provides the opportunities to discover exotic and fascinating topological phases. In this work, we theoretically study the magnon spin-orbit coupling due to the natural dipole-dipole interaction in a layered collinear easy-axis ferrimagnet with two types of ferromagnetic sublayers coupled via antiferromagnetic interlayer exchange interaction, where we predict a nodal-loop semimetal phase and a Weyl semimetal phase in perpendicularly and laterally magnetized geometries, respectively. By driving the spin texture into a spin-canting phase with a magnetic field perpendicular to the easy axis, the nodal loop with a normal easy axis reduces to two Weyl points in the noncollinear spin configuration. Magnon arcs in the Weyl semimetal phases in both geometries are predicted in ferrimagnetic film with finite layers. Our results reveal the role of noncollinear spin texture on magnon topology, which may enrich the investigations in topological ferrimagnonics.