Magnon Dirac materials

TL;DR

This paper shows how a Dirac-like spectrum for magnons can be realized in a 2D honeycomb lattice of magnetic moments, with robustness against interactions and tunability via exchange coupling.

Contribution

It introduces a method to generate and control Dirac magnons in a 2D honeycomb lattice, demonstrating robustness and tunability of the Dirac point.

Findings

Dirac magnon spectrum is generated in a 2D honeycomb lattice.

The Dirac crossing point is robust against magnon-magnon interactions.

Local defects cause impurity resonances and Friedel oscillations.

Abstract

We demonstrate how a Dirac-like magnon spectrum is generated for localized magnetic moments forming a two-dimensional honeycomb lattice. The Dirac crossing point is proven to be robust against magnon-magnon interactions, as these only shift the spectrum. Local defects induce impurity resonances near the Dirac point, as well as magnon Friedel oscillations. The energy of the Dirac point is controlled by the exchange coupling, and thus a two-dimensional array of magnetic dots is an experimentally feasible realization of Dirac magnons with tunable dispersion.