Planar Thermal Hall Effect from Phonons in Cuprates

Journal Article · 11 October 2024 · Physical Review. X

DOI: https://doi.org/10.1103/PhysRevX.14.041011 · OSTI ID:2466277

Chen, Lu ; Le Roux, Léna; Grissonnanche, Gaël ; Boulanger, Marie-Eve ; Thériault, Steven; Liang, Ruixing; Bonn, D. A.; Hardy, W. N.; Pyon, S. ; Takayama, T.; Takagi, H.; Xu, Ke-Jun; Shen, Zhi-Xun; Taillefer, Louis

A surprising “planar” thermal Hall effect, whereby the field is parallel to the current, has recently been observed in a few magnetic insulators; this effect has been attributed to exotic excitations such as Majorana fermions or chiral magnons. Here, we investigate the possibility of a planar thermal Hall effect in three different cuprate materials, in which the conventional thermal Hall conductivity ${\kappa }_{\mathrm{xy}}$ (with an out-of-plane field perpendicular to the current) is dominated by either electrons or phonons. Our measurements show that the planar ${\kappa }_{\mathrm{xy}}$ from electrons in cuprates is zero, as expected from the absence of a Lorentz force in the planar configuration. By contrast, we observe a sizable planar ${\kappa }_{\mathrm{xy}}$ in those samples where the thermal Hall response is due to phonons, even though it should, in principle, be forbidden by the high crystal symmetry. Our findings call for a careful reexamination of the mechanisms responsible for the phonon thermal Hall effect in insulators. Published by the American Physical Society 2024

• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-76SF00515
• OSTI ID: 2466277
• Journal Information: Physical Review. X, Journal Name: Physical Review. X Journal Issue: 4 Vol. 14; ISSN PRXHAE; ISSN 2160-3308
• Publisher: American Physical SocietyCopyright Statement
• Country of Publication: United States
• Language: English