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Abstract Recent studies have demonstrated that the thermal Hall effect (THE) can originate from magnons (magnon Hall effect), phonons (phonon Hall effect), or their combination (magnon–polaron Hall effect). The magnon–polaron Hall effect, first observed in Fe2Mo3O8, is particularly intriguing as its thermal Hall signal can be remarkably large. In this study, we explore the THE in MnPS3, an insulating antiferromagnetic material exhibiting a spin-flop (SF) transition and significant magnetoelastic coupling, making it a strong candidate for studying the THE originating from spin–lattice coupling. We report an exceptionally large thermal Hall angle down to 4 K and show that it cannot be accounted for by standard calculations based on the intrinsic magnon–polaron Berry curvature. Our findings provide an in-depth analysis of the role of the SF transition in the thermal properties of MnPS3and call for further theory development on magnon–phonon coupling and scattering to reveal their influence on transverse heat transport.
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Magnons, Phonons, and Thermal Hall Effect in Candidate Kitaev Magnet α-RuCl3
We study the nature of the debated thermal Hall effect in the candidate Kitaev material α-RuCl3. Without assuming the existence of a gapped spin liquid, we show that a realistic minimal spin model in the canted zigzag phase suffices, at the level of linear spin-wave theory, to qualitatively explain the observed temperature and magnetic field dependence of the non-quantized thermal Hall conductivity κ_xy, with its origin lying in the Berry curvature of the magnon bands. The magnitude of the effect is however too small compared to the measurement by Czajka et al. [Nat. Mater. 22, 36-41 (2023)], even after scanning a broad range of model parameters so as to maximize κ_xy/T. Recent experiments suggest that phonons play an important role, which we show couple to the spins, endowing phonons with chirality. The resulting intrinsic contribution, from both magnons and phonons, is however still insufficient to explain the observed magnitude of the Hall signal. After careful analysis of the extrinsic phonon mechanisms, we use the recent experimental data on thermal transport in α-RuCl3 by Lefrançois et al. [Phys. Rev. X 12, 021025 (2022)] to determine the phenomenological ratio of the extrinsic and intrinsic contributions η≡κ_E/κ_I. We find η=1.2±0.5, which when combined with our computed intrinsic value, explains quantitavely both the magnitude and detailed temperature dependence of the experimental thermal Hall effect in α-RuCl3.
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- Award ID(s):
- 1917511
- PAR ID:
- 10417049
- Date Published:
- Journal Name:
- arXivorg
- ISSN:
- 2331-8422
- Page Range / eLocation ID:
- 2301.07401
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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