Magnetization and electrical resistance are measured on sintered Tl-Ba-Ca-Cu-O samples whose compositions are Tl:Ba:Ca:Cu=2:2:2:3, 2:2:3:3 and 2:2:1:2. The superconducting transition temperature Tc is 114 K for the 2:2:2:3 and 2:2:3:3 samples and is 98 K for the 2:2:1:2 sample. The difference in Tc comes from the numbers of perovskite-like layers between Tl2O2 layers. The upper critical fields Hc2 of the 2:2:2:3 sample increases linearly just below Tc (-(dHc1/dT)Tc=13 kOe/K) and the lower critical field Hc1 increases monotonically with decreasing temperature down to 4.2 K (-(dHc1/dT)Tc=4.5 Oe/K and Hc1(0)=500 Oe). From the results, some superconducting parameters such as ξκλand Hc are calculated.
ASJC Scopus subject areas
- Physics and Astronomy(all)