E. Campillo¹, M. Altangerel¹, J. Baglo¹, A. Vallipuram¹, L. Chen¹, É. Lefrançois¹, C. Lin², B. Keimer²,
G. Grissonnanche³, A. Forget⁴, D. Colson⁴, R. Liang⁵, D. A. Bonn⁵, W. N. Hardy⁵, C. Proust⁶, G. Gu⁷, and L. Taillefer¹
¹Institut quantique, Université de Sherbrooke, Canada
²Max Planck Institute for Solid State Research, Stuttgart, Germany
³École Polytechnique, Paris, France
⁴Université Paris-Saclay, Gif-sur-Yvette, France
⁵University of British Columbia, Vancouver, Canada
⁶Laboratoire National des Champs Magnétiques Intenses, Toulouse, France
⁷Brookhaven National Laboratory, Upton, NY, USA
The thermal Hall effect has emerged as a sensitive probe of both itinerant quasiparticles and chiral phonon excitations in correlated oxides. On the one hand, the transverse thermal conductivity κₓᵧ provides access to the mean free path of d-wave quasiparticles in superconducting cuprates [1]. Measurements across single-, bi- and trilayer systems — HgBa₂CuO₆₊δ (Hg1201), YBa₂Cu₃Oᵧ (YBCO), Bi₂Sr₂CaCu₂O₈₊δ (Bi2212), and HgBa₂Ca₂Cu₃O₈₊δ (Hg1223) — reveal that Hg1223 exhibits a mean free path comparable to that of the cleanest YBCO crystals, whereas Bi2212 shows a ten-times shorter path, pointing to stronger disorder. A cubic temperature dependence of the scattering rate is observed in the cleanest samples, consistent with theoretical expectations for d-wave superconductors [2, 3].
On the other hand, in the insulating regime, κₓᵧ arises predominantly from phonons [4, 5]. The mechanism by which chargeless phonons acquire chirality in a magnetic field remains elusive [6]. Motivated by recent work on Sr₂IrO₄ showing that Rh impurities enhance the phonon thermal Hall signal [7], we have investigated Zn substitution on the Cu site of YBa₂(Cu₁₋ₓZnₓ)₃O₇₋δ at several concentrations. At low temperature (T ≈ 20 K) and 15 T, the ratio κₓᵧ / κₓₓ ≈ 0.1 % remains unchanged from x = 0 to 0.03, indicating that spin-vacancy-induced phonon chirality observed in iridates does not operate in cuprates.
Together, these studies demonstrate how the thermal Hall effect, in both metallic and insulating regimes, offers complementary insights into quasiparticle scattering and the microscopic origin of phonon chirality in cuprates.
References
[1] Zhang et al., Phys. Rev. Lett. 86, 890 (2001).
[2] Walker & Smith, Phys. Rev. B 61, 11285 (2000).
[3] Duffy, Hirschfeld & Scalapino, Phys. Rev. B 64, 224522 (2001).
[4] Kasahara et al., Nature 559, 227 (2018).
[5] Grissonnanche et al., Nature 571, 376 (2019).
[6] Sun, Chen & Kivelson, Phys. Rev. B 106, 144111 (2022).
[7] Ataei et al., Nat. Phys. (in press); arXiv:2302.03796 (2023).