Superconductivity in the Extended Hubbard Model with More Than Nearest-Neighbour Contributions

Abstract

Superconducting phase diagram of the extended Hubbard model supplemented with interaction and hopping terms exceeding nearest neighbour distance in range is analysed systematically at different band-filling and temperature values in a mean-field approximation. The obtained results clearly underline the importance of next-nearest neighbour terms in developing the main superconducting properties of the model system. In particular, the emergence of superconducting phases of different symmetry at a given point of the phase diagram, critical temperatures $T_c$, zero temperature gap amplitude values ${\Delta }_0$, ${\Delta }_0/T_c$ ratios, doping and temperature dependences are all strongly influenced by next-nearest neighbour contributions.

15 pages, 8 embedded ps figures, revtex, final version has been published in Phil. Mag. B