June 2020

Journal

Competing Magnetic Interactions in the Antiferromagnetic Topological Insulator MnBi2Te4

By:
Li, Bing; Yan, Jiaqiang ; Pajerowski, Daniel M; Vaknin, David; Mcqueeney, Robert
Journal Name:
Physical Review Letters
Page Number:
167204
Volume:
124
Issue Number:
16
Publication Date:
June 30, 2020
View DOI Listing:
https://doi.org/10.1103/PhysRevLett.124.167204

Abstract

The antiferromagnetic (AFM) compound MnBi2Te4 is suggested to be the first realization of an AFM topological insulator. We report on inelastic neutron scattering studies of the magnetic interactions in MnBi2Te4 that possess ferromagnetic triangular layers with AFM interlayer coupling. The spin waves display a large spin gap and pairwise exchange interactions within the triangular layer are long ranged and frustrated by large next-nearest neighbor AFM exchange. The degree of frustration suggests proximity to a variety of magnetic phases, potentially including skyrmion phases, which could be accessed in chemically tuned compounds or upon the application of symmetry-breaking fields.