Optical response in the excitonic insulating state: Variational cluster approach

Hengyue Li, Junya Otsuki, Makoto Naka, Sumio Ishihara

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Optical responses in an excitonic insulating (EI) system with strong electron correlation are studied. We adopt the two-orbital Hubbard model with a finite energy difference between the two orbitals where the spin state degree of freedom exists. This model is analyzed by the variational cluster approach. In order to include the local electron correlation effect, the vertex correction is taken into account in the formulation of the optical conductivity spectra. We calculate a finite-Temperature phase diagram in which an EI phase appears between a low-spin band insulating state and a high-spin Mott insulating state. Characteristic components of the optical conductivity spectra consisting of a sharp peak and continuum appear in the EI phase. Integrated intensity almost follows the order parameter of the EI state, suggesting that this component is available to identify the EI phases and transitions.

Original languageEnglish
Article number125117
JournalPhysical Review B
Issue number12
Publication statusPublished - Mar 15 2020
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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