1College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300350 2Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin 300350 3Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin, Tianjin 300350 4Beijing Institute of Radio Measurement, Beijing 100854
Abstract：TlBa$_{2}$Ca$_{2}$Cu$_{3}$O$_{9}$ (Tl-1223) films have promising applications due to their high critical temperature and strong magnetic flux pinning. Nevertheless, the preparation of pure phase Tl-1223 film is still a challenge. We successfully fabricate Tl-1223 thin films on LaAlO$_{3}$ (001) substrates using dc magnetic sputtering and a post annealing two-step method in argon atmosphere. The crystallization temperature of Tl-1223 films in argon is reduced by 100$^{\circ}\!$C compared to that in oxygen. This greatly reduces the volatilization of Tl and improves the surface morphology of films. The lower annealing temperature can effectively improve the repeatability of the Tl-1223 film preparation. In addition, pure Tl-1223 phase can be obtained in a broad temperature zone, from 790$^{\circ}\!$C to 830$^{\circ}\!$C. In our study, the films show homogenous and dense surface morphology using the presented method. The best critical temperature of Tl-1223 films is characterized to be 110 K, and the critical current $J_{\rm c}$ (77 K, 0 T) is up to $2.13\times 10^{6}$ A/cm$^{2}$.
2019, Vol. 36 
