elf-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

抄録

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, {Q}_1=(± \frac{π}{a}, ± \frac{π}{a}) and {Q}_2x=(± \frac{π}{a}, 0), {Q}_2y=(0, ± \frac{π}{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.