Topological magnons for thermal Hall transport in frustrated magnets with bond-dependent interactions

Abstract

Thermal transport in topologically-ordered phases of matter provides valuable insights as it can detect the charge-neutral quasiparticles that would not directly couple to electromagnetic probes. An important example is edge heat transport of Majorana fermions in a chiral spin liquid, which leads to a half-quantized thermal Hall conductivity. This signature is precisely what has recently been measured in $\alpha$-RuCl${}_3$ under external magnetic fields. The plateau-like behavior of the half-quantized thermal Hall conductivity as a function of external magnetic field, and the peculiar sign change depending on the magnetic field orientation, has been proposed as strong evidence for the non-Abelian Kitaev spin liquid. Alternatively, for in-plane magnetic fields, it was theoretically shown that such a sign structure can also arise from topological magnons in the field-polarized state. In this work, we investigate the full implications of topological magnons as heat carriers on thermal transport measurements. We first prove analytically that for any commensurate order with a finite magnetic unit cell, reversing the field direction leads to a sign change in the magnon thermal Hall conductivity in two-dimensional systems. We verify this proof numerically with nontrivial magnetic orders as well as the field-polarized state in Kitaev magnets subjected to an in-plane field. In the case of a tilted magnetic field, whereby there exist both finite in-plane and out-of-plane field components, we find that the plateau-like behavior of the thermal Hall conductivity and the sign change upon reversing the in-plane component of the magnetic field arise in the partially-polarized state, as long as the in-plane field contribution to the Zeeman energy is significant. While these results are consistent with the experimental observations, we comment on other aspects requiring investigation in future studies.

9+4 pages, 17 figures

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Cited by in corpus (45)

• Half-integer quantized anomalous thermal Hall effect in the Kitaev material $\alpha$-RuCl${}_3$
• Robustness of the thermal Hall effect close to half-quantization in a field-induced spin liquid state
• The planar thermal Hall conductivity in the Kitaev magnet α-RuCl3
• Beyond Kitaev physics in strong spin-orbit coupled magnets
• Thermal Hall effects in quantum magnets
• Planar Thermal Hall Effects in Kitaev Spin Liquid Candidate Na2Co2TeO6
• Majorana-fermion origin of the planar thermal Hall effect in the Kitaev magnet $\alpha$-RuCl${}_3$
• Symmetry-based requirement for the measurement of electrical and thermal Hall conductivity under an in-plane magnetic field
• Kitaev Quantum Spin Liquids
• Scanning tunneling spectroscopy of Majorana zero modes in a Kitaev spin liquid
• Planar thermal Hall effect from phonons in a Kitaev candidate material
• Field-angle dependence of thermal Hall conductivity in magnetically ordered Kitaev-Heisenberg system
• Impurity-induced phonon thermal Hall effect in the antiferromagnetic phase of Sr2IrO4
• Flavor-wave theory with quasiparticle damping at finite temperatures: Application to chiral edge modes in the Kitaev model
• Extent of frustration in the classical Kitaev-$\Gamma$ model via bond anisotropy
• Defect-Induced Low-Energy Majorana Excitations in the Kitaev Magnet $\alpha$-RuCl${}_3$
• Thermal Hall effect incorporating magnon damping in localized spin systems
• Spin excitation continuum to topological magnon crossover and thermal Hall conductivity in Kitaev magnets
• Intrinsic Nernst effect of the magnon orbital moment in a honeycomb ferromagnet
• Charge-Neutral Electronic Excitations in Quantum Insulators
• Thermal Hall conductivity of $\alpha$-RuCl${}_3$
• Scattering phenomena for spin transport in Kitaev spin liquid
• Planar thermal Hall effect from phonons in cuprates
• Sign Changes in Heat, Spin, and Orbital Magnon Transport Coefficients in Kitaev Ferromagnets
• Thermal Hall conductivity near field-suppressed magnetic order in a Kitaev-Heisenberg model
• Field-Angle-Resolved Specific Heat in Na${}_2$Co${}_2$TeO${}_6$: Evidence against Kitaev Quantum Spin Liquid
• Topological phase diagrams of in-plane field polarized Kitaev magnets
• Topological phase transitions and thermal Hall effect in a noncollinear spin texture
• Successive topological phase transitions in two distinct spin-flop phases on the honeycomb lattice
• Local spin-flip transitions induced by magnetic quantum impurities in two-dimensional magnets
• Intermediate phases in $\alpha$-RuCl${}_3$ under in-plane magnetic field via interlayer spin interactions
• Anisotropic in-plane heat transport of Kitaev magnet Na${}_2$Co${}_2$TeO${}_6$
• Complex orders and chirality in the classical Kitaev-$\Gamma$ model
• Real-time control of non-Abelian anyons in Kitaev spin liquid under energy dissipation
• Field tuning Kitaev systems for spin fractionalization and topological order
• Majorana Gap Formation in the Anisotropic Kitaev Model with Ordered Flux Configuration
• Formulation of spin Nernst effect for spin-nonconserving insulating magnets
• Angular-Dependent Thermal Hall Effect in a Honeycomb Magnet: Disentangling Kitaev and Dzyaloshinskii-Moriya Interactions
• Intrinsic Thermal Hall Effect in Mott Insulators
• Transport in honeycomb lattice with random $\pi$-fluxes: implications for low-temperature thermal transport in the Kitaev spin liquids
• Spin-phonon coupling and thermal Hall effect in the Kitaev model
• Spin order, spin excitations, and RIXS spectra of spin-1/2 tetramer chains
• Classification of magnon thermal Hall systems based on U(1) to non-Abelian gauge fields
• Multiple topological phases of magnons induced by Dzyaloshinskii-Moriya and pseudodipolar anisotropic exchange interactions in Kagome ferromagnets
• Topological magnons in a non-coplanar magnetic order on the triangular lattice