Excitonic phases in the two-orbital Hubbard model: Roles of Hund's rule coupling

International Conference on Strongly Correlated Electron Systems 2014

Kaneko, Tatsuya^1 ; Ohta, Yukinori^1

Department of Physics, Chiba University, Chiba

263-8522, Japan^1

关键词: Charge density wave state;    Cluster approximation;    Coherence lengths;    Electron hole pairs;    Ground-state energies;    Hund's rule couplings;    Single particle spectrum;    Spin-triplet state;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/592/1/012096/pdf
DOI  :  10.1088/1742-6596/592/1/012096

来源: IOP

【 摘 要 】

Excitonic phases described by the quantum condensation of electron-hole pairs (or excitons) are studied in the two-orbital Hubbard model with the Hund's rule coupling J. Using the variational cluster approximation, we calculate the ground-state energy and order parameters, and show that the Hund's rule coupling always stabilizes the excitonic spin-density- wave state and destabilizes the excitonic charge-density-wave state. The pair coherence lengths calculated in the spin-singlet and spin-triplet states indicate that only the spin-triplet excitons are paired more tightly with increasing J. The single-particle spectrum and density of states are also calculated to clarify the characters of these excitonic density-wave states.