Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1819921 | Physica C: Superconductivity and its Applications | 2007 | 5 Pages |
Abstract
To consider the paring symmetry formed in organic compounds κ-(BEDT-TTF)2X, we study the half-filled-band Hubbard model on an anisotropic triangular lattice (t in two bond directions and tâ² in the other), using an optimization VMC method. As trial states, we adopt a coexisting state of an antiferromagnetic (AF) order and the dx2-y2-wave RVB gap, in addition to the d + id- and d + d-wave gap states. In these states, we take account of the effect of band (or Fermi surface) renormalization. Magnetic Mott transitions occur, and a regime of robust superconductivity could not be found, in contrast with our previous study. In the insulating regime, the coexisting state in which an AF order prevails is always the lowest-energy state up to remarkably large tâ²/t (â²1.3), whereas a dxy-wave RVB state becomes predominant when tâ²/t exceeds this value. In the insulating regime, the effective Fermi surface, determined by the renormalized value tËâ²/t, is markedly renormalized into different directions according to tâ²/t; for tâ²/t â²Â 1.3, it approaches that of the square lattice (tËâ²/t=0), whereas for tâ²/t â³Â 1.3, it becomes almost one-dimensional (tËâ²/tâ«1).
Keywords
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
Tsutomu Watanabe, Hisatoshi Yokoyama, Yukio Tanaka, Jun-ichiro Inoue,