CORRELATION BETWEEN THE DOPING DEPENDENCES OF SUPERCONDUCTING GAP MAGNITUDE 2-DELTA(O) AND PSEUDOGAP TEMPERATURE T-ASTERISK IN HIGH-T-C CUPRATES

We report that in La2-xSrxCuO4 (La214) and Bi2Sr2CaCu2O8+delta (Bi2212 ) the resistivity rho and magnetic susceptibility chi decrease more sh arply below T, corresponding to the onset temperature of a spin gap ( pseudogap) at least for Bi2212. In each system, Ti scales with the sup erconducting 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 tha t 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 co nsidered 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 alp ha J(eff) are nearly one and two for La214 and Bi2212, respectively.