Theory of triangular lattice quasi-one-dimensional charge-transfer solids

R. T. Clay, N. Gomes, S. Mazumdar

Research output: Contribution to journalArticle

Abstract

Recent investigations of the magnetic properties and the discovery of superconductivity in quasi-one-dimensional triangular lattice organic charge-transfer solids have indicated the severe limitations of the effective 12-filled band Hubbard model for these and related systems. We present computational studies within the 14-filled band Hubbard model for these highly anisotropic systems. Individual organic monomer molecules, and not their dimers, constitute the sites of the Hamiltonian within our theory. We find enhancement of the long-range component of superconducting pairing correlations by the Hubbard repulsive interaction U for band parameters corresponding to κ-(BEDT-TTF)2CF3SO3, which is superconducting under moderate pressure. We find significantly weaker superconducting pairing at realistic values of U in κ-(BEDT-TTF)2B(CN)4, and we ascribe the experimentally observed transition to a spin-gapped insulator to the formation of a paired-electron crystal. We make the testable prediction that the spin gap will be accompanied by charge ordering and period doubling in two lattice directions. The weaker tendency to superconductivity in κ-(BEDT-TTF)2B(CN)4 compared to κ-(BEDT-TTF)2CF3SO3 is consistent with the more one-dimensional character of the former. Pressure-induced superconductivity is, however, conceivable. The overall results support a valence bond theory of superconductivity we have proposed recently.

Original languageEnglish (US)
Article number115158
JournalPhysical Review B
Volume100
Issue number11
DOIs
StatePublished - Sep 27 2019

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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