The evolution of electromagnetic response at low frequencies with the development of superconducting condensation in Tl2Ba2CaCu2O8+δ

We report the in-plane temperature dependent ac impedance spectrum of Tl2Ba2CaCu2O8+δ (Tl-2212) single crystal film with thickness 3000 Å and Tc = 96 K. In process of the superconducting condensation, the impedance spectrum z(ω,T0) changed considerably and was very similar with the evolution of the spectrum under various dc bias voltages in the shallow superconducting state. The spectrum weight transfers from high frequency regions to lower ones and eventually diverges towards the dc limit. From the analysis, it seems that the superconducting 'islands' form first and then grow larger, till the formation of a 'continent'. The impedance spectrum z(ω,BI) at various dc bias BI have also been studied.