Entropy changes in crystalline material under phase transition and symmetry breaking

Heat removal from a crystalline material at its critical temperature results in phase transitions which are associated with spontaneous symmetry breaking whereby the final state exhibits infinite degenerate states. Calculations of entropy changes in such systems are not addressed in classical thermodynamics as the system is driven away from equilibrium due to the asymmetric energy landscape of the system. Here, we present a novel mathematical formulation that allows us to calculate entropy changes in such systems while arguing that heat applied to such a system results in an increase in entropy along with the excitation of Goldstone modes. These ideas offer a novel theoretical framework towards understanding the phenomenon of entropy changes in systems driven away from equilibrium. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Heat removal from a crystalline material at its critical temperature leads to phase transitions with infinite degenerate states, as the system is driven away from equilibrium by the asymmetric energy landscape. A novel mathematical formulation is presented to calculate entropy changes in such systems, where heating the system results in an increase in entropy and excitation of Goldstone modes. These ideas provide a new theoretical framework for understanding entropy changes in systems away from equilibrium.