J. Phys. IV France
Volume 114, April 2004
Page(s) 319 - 320

J. Phys. IV France
114 (2004) 319
DOI: 10.1051/jp4:2004114070

Reexamination of the phase diagrams of $\theta $ and $\kappa $-type systems

C. Hotta

IRIKEN, Condensed Molecular Materials Laboratory 2-1, Hirosawa, Wako, 3510198 Saitama, Japan

We propose new phase diagrams of the ground states of $\theta $ and $\kappa $-type organic materials according to our calculations on the extended Hubbard-type model of the anisotropic triangular lattice structure. The relevance to the previously presented experimental phase diagrams are discussed. We argue that the metal-insulator transitions are driven by the change in the anisotropy of band structure as well as by the change in the bandwidth. Both of them vary by the application of pressure, together governing the density of states near the Fermi level. Key words. $\theta $ phase- $\kappa $ phase-anosotropic triangular lattice-extended Hubbard model-MI transition.

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