Magnetic field dependence of the temperature derivative of resistivity: a probe for distinguishing the effects of pseudogap and superconducting fluctuations in cuprates

We have studied the magnetic field dependence of the temperature derivative of the resistivity, dρ(H, T)/dT, of a number of Y1-xCaxBa2(Cu1-yZny)3O7-δ crystalline thin films over a wide range of sample compositions. From the analysis of the temperature derivative data we have been able to distinguish quite clearly between two characteristic temperature scales: (a) the onset of strong superconducting fluctuation temperature, Tscf and (b) the pseudogap temperature, TPG. Significantly different characteristic features of dρ(H, T)/dT at Tscf and at TPG imply that Tscf and TPG have different physical origins