GROWTH AND STRUCTURAL-ANALYSIS OF GDBA2CU3O7 SUPERCONDUCTING THIN-FILMS ON MGO SINGLE-CRYSTAL SUBSTRATES

Thin films of GdBa2Cu3O7 superconductor were grown in situ on MgO single-crystal substrates under different substrate temperatures (T(s)). When T(s) = 800-degrees-C, the films were epitaxially grown with the c axis perpendicular to the film surface. The growth quality was very good, but the zero resistance critical temperature (T(c0)) was only 85 K and the transition width (DELTA-T(c)) was 1.5 K. When T(s) = 670-degrees-C, some of the films were epitaxially grown with the c axis perpendicular to the film surface. Some were mainly c axis oriented with a small amount of (110) and a-axis orientation. The growth quality was relatively poor, but they had T(c0) of 89-91 K and DELTA-T(c) of 0.6-1 K.