Divergence of the Grüneisen ratio at symmetry-enhanced first-order quantum phase transitions

Abstract

Studies of the Grüneisen ratio, i.e., the ratio between thermal expansion and specific heat, have become a powerful tool in the context of quantum criticality, since it was shown theoretically that the Grüneisen ratio displays characteristic power-law divergencies upon approaching the transition point of a continuous quantum phase transition. Here we show that the Grüneisen ratio also diverges at a symmetry-enhanced first-order quantum phase transition, albeit with mean-field exponents, as the enhanced symmetry implies the vanishing of a mode gap which is finite away from the transition. We provide explicit results for simple pseudo-spin models, both with and without Goldstone modes in the stable phases, and discuss implications.

10 pages, 7 figures

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Cited by in corpus (2)

• Analytical results for the unusual Grüneisen ratio in the quantum Ising model with Dzyaloshinskii-Moriya interaction
• Signatures of a Quantum Critical Endpoint in the Kitaev Candidate Na${}_2$Co${}_2$TeO${}_6$