Ring-Exchange Interaction Effects on Magnons in Dirac Magnet CoTiO${}_3$

Abstract

The magnetic interactions that determine magnetic order and magnon energies typically involve only two spins. While rare, multi-spin interactions can also appear in quantum magnets and be the driving force in the ground state selection and in the nature of its excitations. By performing time-domain terahertz and magneto-Raman spectroscopy measurements combined with theoretical modeling, we determine the origin of the magnon excitation gap in Dirac antiferromagnet CoTiO${}_3$. By adding a ring-exchange interaction in a hexagonal plaquette of the honeycomb lattice to both an XXZ spin model and to a low energy spin-orbital flavor wave model, a gap is generated in the magnon spectrum at the Brillouin zone center. With this addition, the flavor wave model reproduces a large swath of experimental results including terahertz, Raman, inelastic neutron scattering, and magnetization experiments.

8 pages, 4 figures in main text, 27 pages and 11 figures in supplement. Published May 21st, 2024 in PRB

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Cited by in corpus (3)

• Long-lived Zone-boundary Magnons in an Antiferromagnet
• Higher order spin interactions mediated by the substrate
• Relevance of on-site and intersite Coulomb interactions in the Kitaev-Heisenberg magnet Na${}_3$Co${}_2$SbO${}_6$