Charge order with structural distortion in organic conductors: Comparison between θ-(ET)2RbZn(SCN)4 and α-(ET) 2I3

Yasuhiro Tanaka, Kenji Yonemitsu

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35 Citations (Scopus)

Abstract

Charge ordering with structural distortion in quasi-two-dimensional organic conductors θ-(ET)2RbZn(SCN)4 (ET = BEDT-TTF) and α-(ET)2I3 is investigated theoretically. By using the Hartree-Fock approximation for an extended Hubbard model which includes both on-site and intersite Coulomb interactions together with Peierls-type electron-lattice couplings, we examine the role of lattice degrees of freedom on charge order. It is found that the experimentally observed, horizontal charge order is stabilized by lattice distortion in both compounds. In particular, the lattice effect is crucial to the realization of the charge order in θ-(ET)2RbZn(SCN)4, while the peculiar band structure whose symmetry is lower than that of θ-(ET)2RbZn(SCN) 4 in the metallic phase is also an important factor in α-(ET)2I3 together with the lattice distortion. For α-(ET)2I3, we obtain a phase transition from a charge-disproportionated metallic phase to the horizontal charge order with lattice modulations, which is consistent with the latest X-ray experimental result.

Original languageEnglish
Article number034708
Journaljournal of the physical society of japan
Volume77
Issue number3
DOIs
Publication statusPublished - 2008 Mar 1

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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