THE PREONSET, TRANSITIONAL, AND FOOT REGIONS IN RESISTANCE VS TEMPERATURE BEHAVIOR IN HIGH-CRITICAL TEMPERATURE SUPERCONDUCTING CUPRATES - INFERENCES REGARDING MAXIMUM CRITICAL-TEMPERATURE

We have studied the pre-onset deviation-from-linearity region, the tra nsitional regime, and the foot region in the resistance vs temperature behavior of high-Critical Temperature oxide superconductors, employin g time-varying magnetic fields and carefully controlled precise temper atures. We have previously shown that the best value of critical tempe rature can be extrapolated from the magnetic field induced divergence of the resistance vs inverse absolute temperature data as derived from the transitional and/or foot regions, and that these data are in acco rd with results from Hall effect studies. The pre-onset region however , shows a differing non-diverging behavior. However sweep magnetic fie ld studies show that, as a function of field, differential resistance data points corresponding to temperature values in the normal state, p re-onset state, and transitional state all lie on a straight line, whe reas data points corresponding to the foot region and zero resistance region deviate from this line. We interpret these data to indicate tha t the phenomena that govern the pre-onset state constitute a different stage of processes that arise initially in the normal state at temper ature slightly greater than the critical temperature, and continue in the transitional state at temperature slightly less than the critical temperature. We believe that the lifetime of the particle that mediate s Cooper-pairing establishes these different stages of the process lea ding to superconductivity in the cuprates.