Effects of Magnetic Field and Temperature on the Critical Current Hysteresis in Tl-Ca-Ba-Cu-O Thin Films

Abstract
The behavior of the critical current density of Tl-Ca-Ba-Cu-O superconducting thin films in a cycling magnetic field was investigated. The hysteresis of the transport J c manifested similar features to those found in polycrystalline Y-Ba-Cu-O and granular Nb, Al thin films in zero-field cooling. However, a novel result of the transport J c in field-cooled samples has been observed. The results were attributed to the presence of a saturated trapped magnetic flux in the weaklink network. The effects of temperature on both the trapped flux and the transport J c suggest the existence of various states of the trapped flux in the Tl-based superconducting thin films.