Study on the Surface Morphology and Superconducting Properties of Tl-2212 Films with Different Thicknesses

Abstract:

Tl-2212 high temperature superconducting (HTS) films were prepared on r-cut sapphire substrates buffered with CeO2 by dc magnetron sputtering technique and post-annealing process. The effects of various thicknesses of Tl-2212 films on their surface morphologies and superconducting properties were investigated. The results show that with increasing of the superconducting film thickness, the dense surface morphology evolves into flake-like crystal structure, the critical temperature Tc and critical current density Jc increase and then decrease, and the microwave surface resistance Rs decreases and then increases. The maximum thickness limitation of the crack-free Tl-2212 films, with CeO2 buffer layers annealed, reaches to 600 nm. The films possess excellent superconducting properties.