Topological magnonic properties of an antiferromagnetic chain

TL;DR

This paper investigates the topological properties of magnonic excitations in a dimerized antiferromagnetic chain, revealing novel phases depending on exchange interactions and anisotropy, with potential realization in MoI$_3$.

Contribution

It introduces a new topological phase in antiferromagnetic chains that differs from the SSH model, supported by analytical and numerical analysis of a real material.

Findings

Identification of topological magnonic phases in antiferromagnetic chains.

Analytical and numerical characterization of these phases.

Potential realization in the material MoI$_3$.

Abstract

The magnonic excitations of a dimerized, one-dimensional, antiferromagnetic chain can be trivial or topological depending on the signs and magnitudes of the alternating exchange couplings and the anisotropy. The topological phase that occurs when the signs of the two different exchange couplings alternate is qualitatively different from that of the Su-Schrieffer-Heeger model. A material that may exhibit these properties is the quasi-one-dimensional material MoI$_3$ that consists of dimerized chains weakly coupled to adjacent chains. The magnetic ground state and its excitations are analyzed both analytically and numerically using exchange and anisotropy parameters extracted from density functional theory calculations.