Correlations in a band insulator

Article

关键词: QUANTUM MONTE-CARLO;    INFINITE DIMENSIONS;    HUBBARD-MODEL;    TRANSITION;    CE3BI4PT3;    FERMIONS;    LATTICE;    GAP;   

DOI  :  10.1103/PhysRevB.80.155116

来源: SCIE

【 摘 要 】

We study a model of a covalent band insulator with on-site Coulomb repulsion at half filling using dynamical mean-field theory. Upon increasing the interaction strength the system undergoes a discontinuous transition from a correlated band insulator to a Mott insulator with hysteretic behavior at low temperatures. Increasing the temperature in the band insulator close to the insulator-insulator transition we find a crossover to a Mott insulator at elevated temperatures. Remarkably, correlations decrease the energy gap in the correlated band insulator. The gap renormalization can be traced to the low-frequency behavior of the self-energy, analogously to the quasiparticle renormalization in a Fermi liquid. While the uncorrelated band insulator is characterized by a single gap for both charge and spin excitations, the spin gap is smaller than the charge gap in the correlated system.

【 授权许可】

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