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

23 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

Fingerprint

Charge density waves
Electron-phonon interactions
electron phonon interactions
Electrons
electrons
Hubbard model
Fermi surface
Coulomb interactions
Crystal lattices
Excitons
Ground state
Fermi surfaces
Monte Carlo method
Condensation
crossovers
Momentum
Monte Carlo methods
condensation
degrees of freedom
excitons

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Charge-density wave induced by combined electron-electron and electron-phonon interactions in 1T- TiSe2 : A variational Monte Carlo study. / Watanabe, Hiroshi; Seki, Kazuhiro; Yunoki, Seiji.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 91, No. 20, 205135, 26.05.2015.

Research output: Contribution to journalArticle

@article{ded38ac1446d498a80d6d184ed342935,
title = "Charge-density wave induced by combined electron-electron and electron-phonon interactions in 1T- TiSe2: A variational Monte Carlo study",
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.",
author = "Hiroshi Watanabe and Kazuhiro Seki and Seiji Yunoki",
year = "2015",
month = "5",
day = "26",
doi = "10.1103/PhysRevB.91.205135",
language = "English",
volume = "91",
journal = "Physical Review B-Condensed Matter",
issn = "0163-1829",
publisher = "American Institute of Physics Publising LLC",
number = "20",

}

TY - JOUR

T1 - Charge-density wave induced by combined electron-electron and electron-phonon interactions in 1T- TiSe2

T2 - A variational Monte Carlo study

AU - Watanabe, Hiroshi

AU - Seki, Kazuhiro

AU - Yunoki, Seiji

PY - 2015/5/26

Y1 - 2015/5/26

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=84930210369&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84930210369&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.91.205135

DO - 10.1103/PhysRevB.91.205135

M3 - Article

AN - SCOPUS:84930210369

VL - 91

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 0163-1829

IS - 20

M1 - 205135

ER -