Superconducting properties of Cu/sub 1-x/Tl/sub x/-1223 [Cu/sub 1-x/Tl/sub x/(Ba,Sr)/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10-y/] thin films

Abstract

The bi-axially-oriented thin films of Cu/sub 1-x/Tl/sub x/(Ba,Sr)/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10-y/(Cu/sub 1-x/Tl/sub x/-1223: x=0.2-1.0) were prepared by an amorphous phase epitaxy (APE) technique on SrTiO/sub 3/ substrates. The amorphous phase was deposited by sputtering on the substrate and annealed in a thallium atmosphere at /spl sim/885/spl deg/C for /spl sim/50 min. Their T/sub c/ values were 100-113 K and higher than those of the YBa/sub 2/Cu/sub 3/O/sub 7-y/ (Y-123, that is, Cu-1212) system. Their J/sub c/ values were 2/spl times/10/sup 7/ A/cm/sup 2/ (77 K, 0 T) and 4/spl times/10/sup 5/ A/cm/sup 2/ (77 K, 10 T) at their maximum for x/spl sim/0.5. The J/sub c/ values were higher than the maximum values of Y-123 thin films by a factor of 2. The high J/sub c/ values are consistent with the low superconducting anisotropy (/spl gamma/=/spl xi//sub ab///spl xi//sub c/=2.5-4) of Cu/sub 1-x/Tl/sub x/-1223 and its high T/sub c/.