Effects of electron-lattice coupling on charge order in θ-(ET) 2X

Yasuhiro Tanaka, Kenji Yonemitsu

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Charge ordering accompanied by lattice distortion in quasi-two dimensional organic conductors θ-(ET) 2X (ET = BEDT-TTF) is studied by using an extended Hubbard model with Peierls-type electron-lattice couplings within the Hartree-Fock approximation. It is found that the horizontal-stripe charge-ordered state, which is experimentally observed in θ-(ET) 2RbZn(SCN) 4, is stabilized by the self-consistently determined lattice distortion. Furthermore, in the presence of the anisotropy in nearest-neighbor Coulomb interactions V ij, the horizontal charge order becomes more stable than any other charge patterns such as diagonal, vertical and 3-fold-type states. At finite temperatures, we compare the free energies of various charge-ordered states and find a first-order transition from a metallic state with 3-fold charge order to the insulating state with the horizontal charge order. The role of lattice degrees of freedom in the realization of the horizontal charge order and the relevance to experiments on θ-(ET) 2X are discussed.

Original languageEnglish
Article number053708
Journaljournal of the physical society of japan
Volume76
Issue number5
DOIs
Publication statusPublished - 2007 May 1
Externally publishedYes

Keywords

  • Charge order
  • Electron-lattice coupling
  • Extended Hubbard model
  • Hartree-Fock approximation
  • Organic conductor

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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