EFFECT OF ELECTRON CORRELATION ON SUPERCONDUCTING PAIRING SYMMETRY

The role of electron correlation on different pairing symmetries are d iscussed in details where the electron correlation has been treated wi thin the slave boson formalism. It is shown that for a pure s or pure d wave pairing symmetry, the electronic correlation suppresses the s w ave gap magnitude (as well as the T-c) at a faster rate than that for the d wave gap. On the other hand, a complex order parameter of the fo rm (s + id) shows anomalous temperature dependence. For example, if th e temperature (T-c(d)) at which the d wave component of the complex or der parameter vanishes happens to be larger than that for the s wave c omponent (T-c(s)), then the growth of the d wave component is arrested with the onset of the s wave component of the order parameter. In thi s mixed phase however, we find that the suppression in different compo nents of the gap as well as the corresponding T-c due to coulomb corre lation are very sensitive to the relative pairing strengths of s and d channels as well as the underlying lattice. Interestingly enough, in such a scenario (for a case of T-c(s) >T-c(d)) the gap magnitude of th e d wave component increases with electron correlation but not T-c(d) for certain values of electron correlation. However, this never happen s in case of the s wave component. We also calculate the temperature d ependence of the superconducting gap along both the high symmetry dire ctions (Gamma - M and Gamma - X) in a mixed s + id symmetry pairing st ate and the thermal variation of the gap anisotropy (Delta Gamma-M/Del ta Gamma-X) with electron correlation. The results are discussed with reference to experimental observations.