Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 31: Correlated Electrons - Low-dimensional Materials I

TT 31.2: Vortrag

Dienstag, 8. März 2005, 14:15–14:30, TU H2053

Numerical study of the two-chain Hubbard model: possible relevance with triplet superconductivity in Bechgaard salts — •Satoshi Nishimoto¹, Yukinori Ohta², Tomonori Shirakawa², and Youji Yamaguchi² — ¹Institut für Theoretische Physik, Universität Göttingen, Germany — ²Department of Physics, Chiba University, Japan

The properties of quasi-one-dimensional Bechgaard salts (TMTSF)₂X have been extensively studied in recent years. This system exhibits a rich phase diagram and the superconducting phase is in proximity to the insulating phase. This is similar to the quasi-two-dimensional organic conductor (BEDT-TTF)₂X and the high-T_c superconductor, in which the d-wave singlet pairing is realized. However, most of recent experiments show strong evidences of triplet pairing in (TMTSF)₂X, and the mechanism of pairing and symmetry of superconducting order parameter are still an open issue. Motivated by such a situation, we study the ground-state properties of a two-chan Hubbard model with zigzag bonds where we include the intra- and inter-site Coulomb repulsions as well as anisotropic hopping parameters. We use the density-matrix renormalization group and exact diagonalization methods to calculate the spin, charge, and pairing correlations of the model. We thereby find enhancement of triplet pairing correlations for some sets of parameter values, which may have some relevance with triplet superconductivity in (TMTSF)₂X.