Kinetic Inductance Measurement of Superconducting YBa sub 2 Cu sub 3 O sub 7 Crystals and Epitaxial Films

Crystals for this study were 25microns-thick platelets, grown in a copper-oxide flux and annealed in O sub 2. Epitaxial films up to 0.25microns thick were grown on (100) SrTiO sub 3 by coevaporation and annealing in O sub 2. In each case the c-axis is oriented normal to the broad surface. The samples were placed between a pair of coils, and the complex sheet impedance was computed from the change in mutual inductance. Because of the large aspect ratio, both types of samples may be considered a thin superconducting sheet, thickness d, with screening current flowing mainly in the a-b plane.