Magnetoelastic coupling driven magnon gap in a honeycomb antiferromagnet
Cobalt titanate, ${\mathrm{CoTiO}}_{3}$, is a honeycomb antiferromagnet recently confirmed experimentally to host Dirac magnons, topological spin-orbit excitons, and chiral phonons. Here, we investigate a magnon gap at the zone center which calls for a refined spin Hamiltonian. We propose a microscopic model for the magnon gap and attribute it to a lattice-distortion (phonon)-induced higher-order spin interaction. Strong magnetoelastic coupling in ${\mathrm{CoTiO}}_{3}$ is also evident in Raman spectra, in which the magnetic order exerts a stronger influence on phonons corresponding to in-plane ionic motions than those with out-of-plane motions. We further examine the evolution of the zone-center magnons in a high magnetic field up to 18.5 T via THz absorption spectroscopy measurements. Based on this field dependence, we propose a spin Hamiltonian that not only agrees with magnon dispersion measured by inelastic neutron scattering but also includes fewer exchange constants and a realistic anisotropy term. Our work highlights the broad implications of magnetoelastic coupling in the study of topologically protected bosonic excitations.
Authors
- Fuyang Tay (ORCID: https://orcid.org/0000-0003-0264-5104)
- Gaihua Ye (ORCID: https://orcid.org/0009-0005-2791-9636)
- Jianshi Zhou (ORCID: https://orcid.org/0000-0002-7667-5640)
- Martin Rodriguez-Vega (ORCID: https://orcid.org/0000-0001-8929-6546)
- Swati Chaudhary (ORCID: https://orcid.org/0000-0002-8504-3602)
- David Lujan
- Jiaming He (ORCID: https://orcid.org/0000-0002-2594-5081)
- Rui He (ORCID: https://orcid.org/0000-0002-2368-7269)
- Gregory A. Fiete (ORCID: https://orcid.org/0000-0001-9477-0804)
- Bowen Ma (ORCID: https://orcid.org/0000-0002-4796-5227)
- Andrey Baydin (ORCID: https://orcid.org/0000-0002-2567-3506)
- Junichiro Kono (ORCID: https://orcid.org/0000-0002-4195-0577)
- Jeongheon Choe (ORCID: https://orcid.org/0000-0002-9272-1133)
- Hiroyuki Nojiri (ORCID: https://orcid.org/0000-0002-9676-7710)
- Cynthia Nnokwe
- Xiaoqin Li (ORCID: https://orcid.org/0000-0002-2279-3078)
Institutions
- Texas Tech University (US)
- Tohoku University (JP)
- Massachusetts Institute of Technology (US)
- Rice University (US)
- The University of Texas at Austin (US)
- Universidad del Noreste (MX)
Publication Details
- Journal
- Physical review. B./Physical review. B
- Published
- 2024-09-13
- DOI
- https://doi.org/10.1103/physrevb.110.104419
- Citations
- 5
- Primary Topic
- Physics of Superconductivity and Magnetism
- Type
- article
- Field-Weighted Citation Impact
- 1.55
Funders
- National Science Foundation
- U.S. Department of Energy
- Welch Foundation
- Gordon and Betty Moore Foundation
- Aspen Center for Physics
- Army Research Office