Growth of YBa₂Cu₃O7-x Superconducting Thin Films on [111] Oriented Ag Films

YBa 2 Cu 3 O 7- x (YBCO) superconducting thin film was prepared on a [111] oriented Ag film using off-axis rf magnetron-sputtering. The [111] oriented Ag film was prepared on the (001) single-crystal natural mica substrate at a substrate temperature of 200° C under argon atmosphere. The YBCO film grew with, not only a strong orientation for the c -axis, but also with the three-symmetrical orientation for a and b axes on the mica/Ag substrate without post-annealing. The full-width at half maximum (FWHM) intensity of the 003 ω-rocking curve of the YBCO film was 1.52°. The optimal substrate temperature was 620° C, when the partial pressure of oxygen was 1.0×10 -2 Torr. T c (onset) and T c (zero) of the films were 84 K and 77 K, respectively, according to the AC magnetic susceptibility measurements. The J c of the film was measured by the conventional four-probe method, and the J c ( J // a b ) value was 1.4×10 4 A/cm 2 at 77 K in a liquid nitrogen bath. The YBCO film showed the thickness dependence of T c to be due to the large lattice mismatch of Ag(111) to YBCO (001).