A new technique to achieve thick Tl2Ba2CaCu2O8 films for advanced applications. Issue 10 (15th May 2023) - Liang, Xuelian
Abstract: Tl2 Ba2 CaCu2 O8 (Tl-2212) high-temperature superconductors (HTS) exhibit excellent superconductivity performance as their critical temperature ( T c ) is higher than 100 K. However, the emergence of microcracks on the film surface restricts the thickness of the obtained Tl-2212 films, thus greatly limiting their scientific research and engineering application. Here, we fabricate crack-free Tl2 Ba2 CaCu2 O8 (Tl-2212) films with a thickness of up to 5 μm on LaAlO3 (001) substrates synthesized by an improved strategy of a closed system. The impact of the thickness of the Tl-2212 films on their crystallographic orientations, T c, critical current density ( J c ) (0 T), critical current intensity ( I c ) (0 T), and microwave surface resistance ( R s ) was systemically explored. As the thickness increases, T c values fluctuate slightly above 100 K while the variation of J c follows the extended strong pinning theory. I c of the 4 μm thick film stays around 80 A at 95 K, and the R s result is less than 1 mΩ at 93 K, indicating their excellent performance at high temperatures. The interaction mechanism between the J c and R s of the Tl-2212 film is replenished in light of the quantitative exploration of J c and R s. This work on Tl-2212 films will promote their fundamental physics research and guide their potential applications in the electronics and electrical field. It can also serve as a reference for future research on other HTS materials.