Temperature and Magnetic Field Dependences of Critical Current of Thallium-Based Superconducting Films

The critical current densities of three superconducting thallium-based films, prepared by screen printing, were measured as a function of temperature and applied magnetic field. The degradation of critical current densities was investigated for two different magnetic field orientations with respect to the sample plane - parallel and perpendicular

Kim-Type Critical State Models and Critical Currents of Thallium Based Superconductors

The two extended formulae in the power form of the Kim critical state model were used to fit the critical currents versus the dc applied magnetic field. Two samples of thallium based superconductors: the $(Tl_{0.6}Pb_{0.24}Bi_{0.16})$$(Sr_{0.9}Ba_{0.1})_2Ca_2Cu_3O_y$ film on single-crystalline lanthanum aluminate and the bulk $(Tl_{0.5}Pb_{0.5})Sr_2(Ca_{1.8}Gd_{0.2})Cu_2O_y$ were chosen to test the models. The formulae were compared to the percolation model described by the exponential expression. The first model fits the experimental data better for the thallium based film whereas the second approach is better for the thallium based bulk sample

Effect of Magnetic Field on Resistive Transition of Thin Film Thallium Based Superconductors

The temperature and magnetic field dependences of a.c. resistance of c-axis oriented (Tl$\text{}_{0.5}$Pb$\text{}_{0.5}$)(Sr$\text{}_{0.8}$Ba$\text{}_{0.2}$)$\text{}_{2}$Ca $\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{x}$ and (Tl$\text{}_{0.6}$Pb$\text{}_{0.24}$Bi$\text{}_{0.16}$)(Sr$\text{}_{0.9}$Ba$\text{}_{0.1}$)$\text{}_{2}$Ca$\text{}_{2}$Cu$\text{}_{3}$ O$\text{}_{x}$ thin films as well as of (Tl$\text{}_{0.5}$Pb$\text{}_{0.5}$)(Sr$\text{}_{0.8}$Ba$\text{}_{0.2}$)$\text{}_{2}$Ca$\text{}_{ }$2Cu$\text{}_{3}$O$\text{}_{x}$ bulk sample from 77 K to room temperature and in magnetic fields from zero to 3000 Oe were measured and analyzed. The magnetic field and temperature dependence of the resistive superconducting transition and irreversibility field were discussed both in the flux-creep model and in the superconducting liquid vortex state model. The temperature width of resistive transition was explained taking advantage of the Ambegaokar and Halperin model of the resistance of superconducting Josephson weak links and barrier of vortex motion presented by Tinkham. The irreversibility field was described by an exponential formula