Spathis, P. N.2; Sørensen, Mads Peter3; Lazarides, Nickos1
1 Department of Informatics and Mathematical Modeling, Technical University of Denmark2 Technical University of Denmark3 Department of Applied Mathematics and Computer Science, Technical University of Denmark
The anisotropic BCS gap equation is applied to a tight-binding model of layered high-temperature superconductors. The possible solutions have s-, d-, and mixed s- and d-wave symmetries using nearest-neighbor intralayer singlet pairing interaction of the same strength in the x and y directions. The transitions from d- or s- to mixed s- and d-wave solutions result from pitchfork bifurcations. In the case of slightly different pairing strength in the x and y directions, perturbed pitchfork bifurcations emerge, leading to a dramatic change in the physical properties of the superconducting state.
Physical Review B Condensed Matter, 1992, Vol 45, Issue 13, p. 7360-7367