Resonant thermal Hall effect of phonons coupled to dynamical defects

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 119; no. 46; pp. 1 - 7
• Main Authors: Guo, Haoyu, Joshi, Darshan G., Sachdev, Subir
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 15.11.2022
• Subjects: Physical Sciences; thermal hall; phonons; cuprates; dynamical defects
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2215141119

We present computations of the thermal Hall coefficient of phonons scattering off a defect with multiple energy levels. Using a microscopic formulation based on the Kubo formula, we find that the leading contribution perturbative in the phonon–defect coupling is proportional to the phonon lifetime and has a “side-jump” interpretation. Consequently, the thermal Hall angle is independent of the phonon lifetime. The contribution to the thermal Hall coefficient is at resonance when the phonon energy equals a defect-level spacing. Our results are obtained for three different defect models, which apply to different correlated electron materials. For the pseudogap regime of the cuprates, we propose a model of phonons coupled to an impurity quantum spin in the presence of quasistaticmagnetic order with an isotropic Zeeman coupling to the applied field and without spin–orbit interaction.