Self-consistent screening enhances the stability of the nonequilibrium excitonic insulator phase

Article

关键词: ELECTRON-HOLE GAS;    GIANT BANDGAP RENORMALIZATION;    2-DIMENSIONAL MATERIALS;    BOSE-CONDENSATION;    CARRIER DYNAMICS;    GROUND-STATE;    METAL;    OPTOELECTRONICS;    SEMICONDUCTORS;    BIEXCITONS;   

DOI  :  10.1103/PhysRevB.102.085203

来源: SCIE

【 摘 要 】

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).

【 授权许可】

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