Topological magnonics

摘要

Spin waves, whose quanta are called magnons, are propagating excitations of magnetic materials. Magnonics is an emerging field of modern condensed matter physics that aims to study and utilize the properties and behaviors of magnons. The topological magnon band is an interesting topic of magnonics, and nontrivial topology is usually accompanied with many exotic phenomena such as emergence of robust edge states and the magnon Hall effect. In this Tutorial, using a honeycomb ferromagnet as a prototypical platform, we pedagogically demonstrate how to compute the magnon spectra and the topological invariants characterizing the topology of the magnon bands. We also briefly discuss some numerical techniques.