The nonequilibrium excitonic insulator (NEQ-EI) is an excited state of matter characterized by a finite density of coherent excitons and a time-dependent macroscopic polarization. The stability of this exciton superfluid as the density grows is jeopardized by the increased screening efficiency of the looser excitons. In this work we put forward a Hartree plus screened exchange scheme to predict the critical density at which the transition toward a free electron-hole plasma occurs. The dielectric function is calculated self-consistently using the NEQ-EI polarization and found to vanish in the long-wavelength limit. This property makes the exciton superfluid stable up to relatively high densities. Numerical results for the MoS2 monolayers indicate that the NEQ-EI phase survives up to densities of the order of 10(12) cm(-)(2).
Perfetto, E., Marini, A., Stefanucci, G. (2020). Self-consistent screening enhances the stability of the nonequilibrium excitonic insulator phase. PHYSICAL REVIEW. B, 102(8) [10.1103/PhysRevB.102.085203].
Self-consistent screening enhances the stability of the nonequilibrium excitonic insulator phase
Perfetto E;Stefanucci G
2020-01-01
Abstract
The nonequilibrium excitonic insulator (NEQ-EI) is an excited state of matter characterized by a finite density of coherent excitons and a time-dependent macroscopic polarization. The stability of this exciton superfluid as the density grows is jeopardized by the increased screening efficiency of the looser excitons. In this work we put forward a Hartree plus screened exchange scheme to predict the critical density at which the transition toward a free electron-hole plasma occurs. The dielectric function is calculated self-consistently using the NEQ-EI polarization and found to vanish in the long-wavelength limit. This property makes the exciton superfluid stable up to relatively high densities. Numerical results for the MoS2 monolayers indicate that the NEQ-EI phase survives up to densities of the order of 10(12) cm(-)(2).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.