Charge-density wave induced by combined electron-electron and electron-phonon interactions in 1T- TiSe2: A variational Monte Carlo study

Hiroshi Watanabe, Kazuhiro Seki, Seiji Yunoki

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

To clarify the origin of a charge-density wave (CDW) phase in 1T-TiSe2, we study the ground-state property of a half-filled two-band Hubbard model in a triangular lattice including electron-phonon interaction. By using the variational Monte Carlo method, the electronic and lattice degrees of freedom are both treated quantum mechanically on an equal footing beyond the mean-field approximation. We find that the cooperation between Coulomb interaction and electron-phonon interaction is essential to induce the CDW phase. We show that the "pure" exciton condensation without lattice distortion is difficult to realize under the poor nesting condition of the underlying Fermi surface. Furthermore, by systematically calculating the momentum-resolved hybridization between the two bands, we examine the character of electron-hole pairing from the viewpoint of BCS-BEC crossover within the CDW phase and find that the strong-coupling BEC-like pairing dominates. We therefore propose that the CDW phase observed in 1T-TiSe2 originates from a BEC-like electron-hole pairing.

Original languageEnglish
Article number205135
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume91
Issue number20
DOIs
Publication statusPublished - 2015 May 26
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

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