High critical current density in Ag-doped Bi-2212 thin films

Abstract

We have investigated the effect of Ag doping on the superconducting properties of Bi-2212 thin films deposited on single-crystalline (100) MgO substrate using pulsed laser deposition (PLD), post annealed at 845 °C for various lengths of time. X-ray diffraction measurements showed that all the films are c-axis oriented. Resistivity measurements showed that the superconducting onset transition temperature (Tc−onset) and zero resistive temperature (Tc−zero) for the best films are 95 K and 75 K, respectively. The highest critical current density obtained from magnetic measurements for the undoped film is Jc = 6.3 × 106 A cm−2 in 0.5 T magnetic field at 5 K. Compared to undoped films, silver-doped films showed a sharp superconducting transition and improved weak links and thus high critical current density. Among the silver-doped films, the 5 wt% silver-doped Bi-2212 film showed highest Jc = 7.5 × 106 A cm−2 at 0.5 T and 5 K, which is higher than that for the undoped Bi-2212 film. Below Tc, a double sign reversal of the Hall effect has been observed in undoped Bi-2212 film.