SUPERCONDUCTIVITY IN ARTIFICIALLY LAYERED BA-CA-CU-O THIN-FILMS

Thin films of Ba-Ca-Cu-0 have been grown by successive deposition of BaCuO2 and CaCuO2 layers with different numbers of each layer. The samples of (BaCuO2)3 + (CaCuO2)1 show a zero resistance at 30-38 K with the onset of 70-80 K. The diamagnetic transition is also observed below 26-30 K. X-ray diffraction analysis shows the c-axis orientation of the films with a lattice constant of c = 15.38 angstrom. This value is nearly equal to the sum of three times BaCuO2'S c-axis length plus the CaCuO2'S c-axis length based on the infinite layer structure of BaCuO2 and CaCuO2. By means of an artificial layer-by-layer growth process, a new superconducting system of layered Ba-Ca-Cu-O structure is formed.