Competition mechanism between singlet and triplet superconductivity in the tight-binding model with anisotropic attractive potential
Institute of Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
Corresponding author: a Mateusz.Krzyzosiak@pwr.wroc.pl
Revised: 22 November 2005
Published online: 17 February 2006
Based upon the tight-binding formalism a model of a high-Tc superconductor with isotropic and anisotropic attractive interactions is considered analytically. Symmetry facets of the group C4v are included within a method of successive transformations of the reciprocal space. Complete sets of basis functions of C4v irreducible representations are given. Plausible spin-singlet and spin-triplet superconducting states are classified with regard to the chosen basis functions. It is displayed that pairing interaction coefficients and the dispersion relation, which can be characterized by the parameter η= 2t1/t0, have a diverse and mutually competing influence on the value of the transition temperature. It is also shown that in the case of a nearly half-filled conduction band and an anisotropic pairing interaction the spin-singlet d-wave symmetry superconducting state is realized for small values of the parameter η, whereas in the opposite limit, for sufficiently large values, the spin-triplet p-wave symmetry superconducting state has to be formed. This result cannot be obtained within the Van Hove scenario or BCS-type approaches, where the p-wave symmetry superconducting state absolutely dominates. The specific heat jump and the isotope shift as functions of the parameter η are assessed and discussed for the d-wave symmetry singlet and the p-wave symmetry triplet states.
PACS: 74.20.Rp – Pairing symmetries (other than s-wave) / 74.62.Yb – Other effects
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2006