Thermal conductivity near the quantum critical point in TmVO₄

Thulium vanadate (TmVO₄) is a model system for exploring electronic nematicity, undergoing a continuous ferroquadrupolar (nematic) phase transition at 2.15 K that can be tuned with magnetic field to a T = 0 quantum critical point. The quadrupolar moments of local Tm-ion 4f orbitals are strongly coupled to lattice strain, with a cooperative Jahn-Teller distortion from tetragonal to orthorhombic at the transition. Although the transition at low field can be well described by a mean-field semiclassical treatment of the transverse-field Ising model, clear deviations have been observed upon approaching the quantum critical point [1].

As a probe sensitive to lattice dynamics as seen via phonon transport, thermal conductivity is well suited for investigating this physics. Here we present our measurements of the thermal conductivity of TmVO₄ as a function of magnetic field at dilution fridge temperatures, focusing particularly on the phase boundary in the vicinity of the quantum critical point.

[1] P. Massat et al., PNAS 119, e2119942119 (2022).