Mixing of superconducting d x2− y2 state with s-wave states for different filling and temperature

Abstract

We study the order parameter for mixed-symmetry states involving a major d x 2− y 2 state and various minor s-wave states (s, s xy , and s x 2+ y 2 ) for different filling and temperature for mixing angles 0 and π/2. We employ a two-dimensional tight-binding model incorporating second-neighbor hopping for tetragonal and orthorhombic lattice. There is mixing for the symmetric s state both on tetragonal and orthorhombic lattice. The s xy state mixes with the d x 2− y 2 state only on orthorhombic lattice. The s x 2+ y 2 state never mixes with the d x 2− y 2 state. The temperature dependence of the order parameters is also studied.