Resumen de A comparison of optimal doping behaviors between d− and s*− wave superconducting ground states
B. Millán, I. J. Hernández Hernández, L.A. Pérez, J. Samuel Millán
In a previous work reported in this journal, the thermodynamical properties of d-wave superconducting ground states close to half filling were obtained by using a generalized Hubbard model. In the present work, extended s-wave (s* ) symmetry superconducting ground states are considered within the same model and a comparison is made between these two symmetries for those properties depending on the carrier density (n) and first- (t) and second-neighbor (t´ ) electron hopping parameters. For s*-wave superconducting states, the electron-electron interaction Hamiltonian parameters is fixed as in the d-wave case with ∆t = 0.5 eV, ∆t3 = 0.05 eV, and two cases were studied; U = 0 and U = 2 eV. Without considering the diluted regime (n → 0), in the interval n ∈ [0, 1], for both symmetries, the maximum critical temperatures (T_(c,max)) at optimal doping (n_(op)) are lower than those attained at high electron densities n ∈ [1, 2]. The superconducting gap at T = 0 K and the corresponding ground state energy (E_(g)), for all the carrier concentrations, were also obtained. The superconductor state with d-wave symmetry does not depend on U and a supremum for n_(op)(n_(op,sup)), where both T_(c,max)(n_(op,t´) and E_(g)(n_(op,t´) are minimum, can be found close to half filling. However, in general, for a s -wave superconductor T_(c,max) and E_(g) attain their minimum values at different (n_(op, t´)) points and a n_(op,sup) cannot be properly defined.
