# Competing magnetic interactions in the antiferromagnetic topological insulator MnBi$_{2}$Te$_{4}$

## TL;DR

This study investigates the magnetic interactions in MnBi$_{2}$Te$_{4}$, revealing frustrated exchange interactions and proximity to complex magnetic phases like skyrmions, which are relevant for topological and magnetic research.

## Contribution

The paper provides the first inelastic neutron scattering analysis of magnetic interactions in MnBi$_{2}$Te$_{4}$, highlighting frustration and potential for novel magnetic phases.

## Key findings

- Large spin gap observed in spin waves
- Frustrated exchange interactions within layers
- Proximity to skyrmion and other complex magnetic phases

## Abstract

The antiferromagnetic (AF) compound MnBi$_{2}$Te$_{4}$ is suggested to be the first realization of an antiferromagnetic (AF) topological insulator. Here we report on inelastic neutron scattering studies of the magnetic interactions in MnBi$_{2}$Te$_{4}$ that possess ferromagnetic (FM) triangular layers with AF interlayer coupling. The spin waves display a large spin gap and pairwise exchange interactions within the triangular layer are frustrated due to large next-nearest neighbor AF exchange. The degree of frustration suggests proximity to a variety of magnetic phases, potentially including skyrmion phases, that could be accessed in chemically tuned compounds or upon the application of symmetry-breaking fields.