Mixing of superconducting d x 2 − y 2 state with s - wave states for different filling and temperature

We study the order parameter for mixed-symmetry states involving a major dx2−y2 state and various minor s-wave states (s, sxy, and sx2+y2) 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 sxy state mixes with the dx2−y2 state only on orthorhombic lattice. The sx2+y2 state never mixes with the dx2−y2 state. The temperature dependence of the order parameters is also studied. PACS number(s): 74.20.Fg, 74.62.-c, 74.25.Bt