Quantum annealed criticality: A scaling description

Abstract

Experimentally there exist many materials with first-order phase transitions at finite temperature that display quantum criticality. Classically, a strain-energy density coupling is known to drive firstorder transitions in compressible systems, and here we generalize this Larkin-Pikin 1 mechanism to the quantum case. We show that if the T = 0 system lies above its upper critical dimension, the line of first-order transitions ends in a "quantum annealed critical point" where zero-point fluctuations restore the underlying criticality of the order parameter. The generalized Larkin-Pikin phase diagram is presented and experimental consequences are discussed.

Giant lattice softening at a Lifshitz transition in Sr 2 RuO 4

“…If ν( d + z ) > 2, then the universal temperature correction is small and positive and the system is mechanically stable. Conversely, the system must undergo an instability, defined by a vanishing elastic constant at a nonzero temperature, if the quantum Harris criterion ν( d + z ) < 2 ( 27 , 28 ) is fulfilled. Then, the above scaling theory of a “naked” QCP ceases to be valid; the system either crosses over to a new critical regime where strain becomes a genuine dynamical quantum critical mode or undergoes a phase transition to another state of matter.…”