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

摘要: Recent investigations of the magnetic properties and discovery superconductivity in quasi-one-dimensional triangular lattice organic charge-transfer solids have indicated severe limitations effective $\frac{1}{2}$-filled band Hubbard model for these related systems. We present computational studies within $\frac{1}{4}$-filled highly anisotropic Individual monomer molecules, not their dimers, constitute sites Hamiltonian our theory. find enhancement long-range component superconducting pairing correlations by repulsive interaction $U$ parameters corresponding to $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{BEDT-}\mathrm{TTF})}_{2}{\mathrm{CF}}_{3}{\mathrm{SO}}_{3}$, which is under moderate pressure. significantly weaker at realistic values $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{BEDT-}\mathrm{TTF})}_{2}\mathrm{B}{(\mathrm{CN})}_{4}$, we ascribe experimentally observed transition a spin-gapped insulator formation paired-electron crystal. make testable prediction that spin gap will be accompanied charge ordering period doubling two directions. The tendency $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{BEDT-}\mathrm{TTF})}_{2}\mathrm{B}{(\mathrm{CN})}_{4}$ compared $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{BEDT-}\mathrm{TTF})}_{2}{\mathrm{CF}}_{3}{\mathrm{SO}}_{3}$ consistent with more one-dimensional character former. Pressure-induced is, however, conceivable. overall results support valence bond theory proposed recently.