Correlation between the doping dependences of superconducting gap magnitude 2Δo and pseudogap temperature T* in high-Tc cuprates

We report that in La2-xSrxCuO4 (La214) and Bi2Sr2CaCu2O8+delta (Bi2212) the resistivity rho and magnetic susceptibility chi decrease more sharply below T*, corresponding to the onset temperature of a spin gap (pseudogap) at least for Bi2212. In each system, Ti scales with the superconducting gap magnitude 2 Delta(0) (T* similar to 2 Delta(0)/4.3k(B)), which increases as the doping level is lowered. We also report that 2 Delta(0) is almost proportional to T-max (>T*), where T-max is the temperature exhibiting a broad peak of chi and k(B)T(max) has been considered to give the measure of effective exchange energy J(eff); the alpha factors in 2 Delta(0) similar to alpha k(B)T(max) similar to alpha J(eff) are nearly one and two for La214 and Bi2212, respectively.