Low-temperature field dependence of thermal conductivity in α-RuCl₃

The layered honeycomb compound α-RuCl₃ continues to attract great interest as a leading candidate material in which to experimentally realize Kitaev quantum spin liquid physics. Early thermal transport measurements [1] reported a plateau region of half-integer-quantized 2D thermal Hall conductance ascribed to protected chiral Majorana edge currents of the Kitaev quantum spin liquid; however, attempts to reproduce this result have seen conflicting reports from different groups [2, 3]. More recently, 1/H-periodic oscillatory behavior was reported in the in-plane field dependence of longitudinal thermal conductivity [3], strongly reminiscent of quantum oscillations in a metal, and hypothesized here to derive from a spinon Fermi surface: a tantalizing possibility begging further experimental confirmation.

Here we present our study of the longitudinal thermal conductivity in α-RuCl₃ as a function of magnetic field, at dilution refrigerator temperatures and for different orientations of magnetic field and heat current. We compare to other recently published results and discuss possible interpretations of the observed anomalous field dependence.

[1] Kasahara et al., Nature 559, 227 (2018).

[2] Bruin et al., arXiv:2104.12184 (2021).

[3] Czajka et al., Nat. Phys. 17, 915 (2021).