Excitonic insulator state in the two-orbital Hubbard model: Variational cluster approach

被引：63
作者：
Kaneko, T. [1 ]
Seki, K. [1 ]
Ohta, Y. [1 ]
机构：
[1] Chiba Univ, Dept Phys, Chiba 2638522, Japan
来源：
PHYSICAL REVIEW B | 2012年 / 85卷 / 16期
关键词：
TRANSITION;
D O I：
10.1103/PhysRevB.85.165135
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
The variational cluster approximation is used to study the spontaneous symmetry breaking of the excitonic insulator (EI) state in the two-orbital Hubbard model defined on the two-dimensional square lattice. Evaluating the order parameter of the EI state, staggered magnetization, and number of particles on each orbital, we obtain the ground-state phase diagram of the model in a wide parameter space of the intra and interorbital Coulomb interactions. We also calculate the single-particle and anomalous Green's functions. We show that the normal metallic phase is unstable to the formation of the EI state and the EI phase appears in a wide parameter region between the band-insulator and Mott-insulator phases.
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页数：7
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