Self-Consistent Calculations of Eliashberg Equation for Strong Coupling Superconductivity with Anisotropic Gap under the Modulation of Two Kinds of Nodal Wavevectors to 2-Dimensional Electronic Bands

We investigate the role of the competition between two kinds of wavevectors Q j in the appearance of an anisotropic superconducting gap in 2-dimensional systems on a square lattice with strong antiferromagnetic correlations. We take into account the effect of interaction between carriers via wavevectors, \({{\mib Q}}_1=(\pm \frac{\pi}{a},\pm \frac{\pi}{a})\) and \({{\mib Q}}_{2x}=(\pm \frac{\pi}{a},0),{{\mib Q}}_{2y}=(0,\pm \frac{\pi}{a})\). (Here, a is the lattice constant.) We treat the strong coupling superconductivity by using Eliashberg-Migdal equations for superconducting phases. On the basis of the numerical calculation, we discuss how the symmetric properties of the gap and values of T c are related to the ratio of the strength of interactions for Q 1 and Q 2 .