SU(3) Topology of Magnon-Phonon Hybridization in 2D Antiferromagnets

• Published in: Physical review letters Vol. 124; no. 14; p. 147204
• Main Authors: Zhang, Shu, Go, Gyungchoon, Lee, Kyung-Jin, Kim, Se Kwon
• Format: Journal Article
• Language: English
• Published: United States 10.04.2020
• ISSN: 1079-7114
• DOI: 10.1103/physrevlett.124.147204

Magnon-phonon hybrid excitations are studied theoretically in a two-dimensional antiferromagnet with an easy axis normal to the plane. We show that two magnon bands and one phonon band are intertwined by the magnetoelastic coupling through a nontrivial SU(3) topology, which can be intuitively perceived by identifying a skyrmion structure in the momentum space. Our results are insensitive to lattice details and generally applicable to two-dimensional antiferromagnets. We show this by developing a continuum theory as the long-wavelength approximation to the tight-binding model. The theoretical results can be probed by measuring the thermal Hall conductance as a function of the temperature and the magnetic field. We envision that the magnetoelastic coupling in antiferromagnets can be a promising venue in search of various topological excitations, which cannot be found in magnetic or elastic models alone.