PAIRING THEORY OF HIGH AND LOW-TEMPERATURE SUPERCONDUCTORS

A scenario which can account for all observed features of both high-T- c superconductors (HTS) and low-T-c superconductors (LTS) is discussed . This scenario is based on the fact that a finite pairing interaction energy range T-d is required to have a finite value of T-c and that n ot all carriers participate in pairings, yielding multiconnected super conductors (MS). A new density of states, derived by keeping the order parameter zero outside of T-d, is shown to account for the observed l ow energy states in HTS and for the temperature dependences in the spe cific heat, the penetration depth, the optical conductivity, and the t unneling conductance data. I argue that the notion of MS can account f or the tunneling data along the a(or b)-, ab-, and c-axis, and the 1/2 flux quantum observed in BTS. The region occupied by unpaired carrier s can be considered as a vortex with a fluxoid quantum number equal to I (VF), II (VZF), or -1 (VAF) when the magnetic flux around the vorte x is greater than, equal to, or less than the effective flux produced by the supercurrent, respectively. The Hall anomaly depends on the rel ative strengths of the contributions via VF and VAF. The fact that the present scenario can account for all observed features of HTS and LTS suggests that the symmetry of the order parameter in HTS may not be d ifferent from one in LTS.