Superconducting Gap in the Tunneling Spectra of High-T_c Cuprates

Abstract

In Bi2212 and La214, the low-T(T ≪ T c ) superconducting gap magnitude 2Δ0 and the temperature dependence of in-plane resistivity ρ were examined over a wide carrier-doping range. In both systems, 2Δ0 increases with lowering doping level and ρ starts decreasing faster around a temperature T*, comparable to the mean-field T c or the onset temperature of a spin-channel singlet formation in the mean-field RVB thory, each of which is given by ~Δ0/2k B .