Recent experiments demonstrate the induction of long-range order in correlated electron systems via external perturbations, which calls for a better understanding of nonthermal ordered states and nonequilibrium symmetry breaking. Here, we reveal a mechanism based on entropy cooling and entropy trapping in a strongly correlated multiorbital system. We consider a two-orbital Hubbard model with Hund coupling and crystal-field splitting and show that in the vicinity of a spin-state transition, crystal-field quenches can induce an excitonic condensation at initial temperatures above the highest ordering temperature in equilibrium. We furthermore identify a dynamical phase transition in the evolution of the order parameter and show that such quenches can result in long-lived nonthermal excitonic condensates which have no analog in the equilibrium phase diagram.

• Received 3 June 2020
• Revised 17 November 2020
• Accepted 18 November 2020

DOI:https://doi.org/10.1103/PhysRevB.102.241103