Experimentally there exist many materials with first-order phase transitions at finite temperature that display quantum criticality, and I’ll discuss a theoretical framework for this observed behavior. Classically a strain-energy density coupling is known to drive first-order transitions in compressible systems. This Larkin-Pikin mechanism can be re-expressed in the language of correlation and response functions that it can be generalized to the quantum case. I’ll show that if the T=0 system lies above its upper critical dimension, the line of first-order transitions can end in a quantum annealed critical point where zero-point fluctuations restore the underlying criticality of the order parameter. Implications for experiment particularly in pressure-tuned ferroelectrics will be discussed. The possibility of quantum criticality in compressible materials, magnetic and ferroelectric, suggests new settings for the exploration of exotic quantum phases where a broad temperature range can be probed with easily accessible pressures due to the lattice-sensitivity of these systems.

P. Chandra, P. Coleman, M.A. Continentino and G.G. Lonzarich, arXiv1805.1171.