The nature of the hidden-order (HO) state in ${\mathrm{URu}}_2{\mathrm{Si}}_2$ remains one of the major unsolved issues in heavy-fermion physics. Recently, torque magnetometry, x-ray diffraction, and elastoresistivity data have suggested that the HO phase transition at $T_{\mathrm{HO}}\approx 17.5\mathrm{K}$ is driven by electronic nematic effects. Here, we search for thermodynamic signatures of this purported structural instability using anisotropic thermal expansion, Young’s modulus, elastoresistivity, and specific-heat measurements. In contrast to the published results, we find no evidence of a rotational symmetry breaking in any of our data. Interestingly, our elastoresistivity measurements, which are in full agreement with published results, exhibit a Curie-Weiss divergence, which we however attribute to a volume and not to a symmetry-breaking effect. Finally, clear evidence for thermal fluctuations is observed in our heat-capacity data, from which we estimate the HO correlation length.

• Received 31 December 2019
• Accepted 27 May 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.257601