Topological Magnetoelastic Excitations in Non-Collinear Antiferromagnets

Abstract

We study the topological property of the magnetoelastic excitation in non-collinear antiferromagnets. As a toy model, we consider the magnon-phonon coupling in a triangular antiferromagnet with a $120^{\circ }$ Nèel order. We find that in the presence of out-of-plane external magnetic field, the magnon-polaron bands, which arise from hybridization of magnons and phonons, can carry Chern number, even though the individual magnon and phonon bands are topologically trivial. Large Berry curvature is induced from the anti-crossing regions between the magnon and phonon bands, which renormalizes the thermal Hall conductivity of phonon bands. To compute the Berry curvature and Chern number of magnon-polarons, we give a simple algorithm to diagonalize magnetoelastic Hamiltonian without diagonalizing the phonon Hamiltonian, by mapping the problem to the diagonalization of bosonic Bogoliubov-de-Gennes (BdG) Hamiltonian. This is necessary because the contribution to the Berry curvature from phonon cannot be properly captured if we compute the Berry curvature from magnetoelastic Hamiltonian whose phonon sector has been already diagonalized.

20 pages, 10 figures

References in corpus (9)

• Observation of the Magnon Hall Effect
• Theoretical prediction of rotating magnon wavepacket in ferromagnets
• Topological Nature of the Phonon Hall Effect
• Magnetization plateaus in frustrated antiferromagnetic quantum spin models
• Excitation spectra of the spin-1/2 triangular-lattice Heisenberg antiferromagnet
• Coherent elastic excitation of spin waves
• Spontaneous decays of magneto-elastic excitations in noncollinear antiferromagnet (Y,Lu)MnO3
• Berry curvature in magnon-phonon hybrid systems
• The phonon Hall effect: theory and application

Cited by in corpus (10)

• Chirality selective magnon-phonon hybridization and magnon-induced chiral phonons in a layered zigzag antiferromagnet
• Topological magnetic excitations
• Evidence for magnon-phonon coupling in the topological magnet Cu${}_3$TeO${}_6$
• Magnetoelastic coupling enabled tunability of magnon spin current generation in 2D antiferromagnets
• Magnonic Analogue of Edelstein Effect in Antiferromagnetic Insulators
• Thermal Hall effect in a van der Waals ferromagnet CrI3
• Sizable suppression of magnon Hall effect by magnon damping in Cr${}_2$Ge${}_2$Te${}_6$
• Berry curvature for coupled waves of magnons and electromagnetic waves
• Coherent strong-coupling of terahertz magnons and phonons in a Van der Waals antiferromagnetic insulator
• Topological excitations in quasi two-dimensional quantum magnets with weak interlayer interactions