Planar Thermal Hall Effects in Kitaev Spin Liquid Candidate Na2Co2TeO6

Abstract

We investigate both the longitudinal thermal conductivity (${\kappa }_{xx}$) and the planar thermal Hall conductivity (${\kappa }_{xy}$) in the Kitaev spin liquid candidate of Co-based honeycomb antiferromagnet Na${}_2$Co${}_2$TeO${}_6$ in a magnetic field ($B$) applied along the $a$ and $a^{\ast }$ axes. A finite ${\kappa }_{xy}$ is resolved for both field directions in the antiferromagnetic (AFM) phase below the Néel temperature of 27 K. The temperature dependence of ${\kappa }_{xy}/T$ shows the emergence of topological bosonic excitations. In addition, the field dependence of ${\kappa }_{xy}$ shows sign reversals at the critical fields in the AFM phase, suggesting the changes in the Chern number distribution of the topological magnons. Remarkably, a finite ${\kappa }_{xy}$ is observed in $B\parallel a^{\ast }$ between the first-order transition field in the AFM phase and the saturation field, which is prohibited in a disordered state by the two-fold rotation symmetry around the $a^{\ast }$ axis of the honeycomb lattice, showing the presence of a magnetically ordered state that breaks the two-fold rotation symmetry. Our results demonstrate the presence of topological magnons in this compound in the whole field range below the saturation field.

7 pages, 5 figures, and Supplementary Materials. To appear in Phys. Rev. Research

References in corpus (12)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Topological Magnon Insulator in Insulating Ferromagnet
• Topological Nature of the Phonon Hall Effect
• Pseudospin exchange interactions in d^7 cobalt compounds: Possible realization of the Kitaev model
• Kitaev-Heisenberg Hamiltonian for High-Spin $d^7$ Mott Insulators
• Hall effect of triplons in a dimerized quantum magnet
• Kitaev interactions in the Co honeycomb antiferromagnets Na${}_3$Co${}_2$SbO${}_6$ and Na${}_2$Co${}_2$TeO${}_6$
• Magnetic properties of the honeycomb oxide Na${}_2$Co${}_2$TeO${}_6$
• Zigzag antiferromagnetic ground state with anisotropic correlation lengths in the quasi-2D honeycomb lattice compound Na2Co2TeO6
• Berry curvature in magnon-phonon hybrid systems
• Significant thermal Hall effect in the 3$d$ cobalt Kitaev system $N{a}_{2}C{o}_{2}Te{O}_6$
• High-field thermal transport properties of the Kitaev quantum magnet alpha-RuCl3: evidence for low-energy excitations beyond the critical field

Cited by in corpus (2)

• Symmetry-based requirement for the measurement of electrical and thermal Hall conductivity under an in-plane magnetic field
• Field and Polarization Dependent Quantum Spin Dynamics in Honeycomb Magnet Na${}_2$Co${}_2$TeO${}_6$: Magnetic Excitations and Continuum