Flux-creep and critical currents in various Y-Ba-Cu-O-samples

Abstract

Using contactless torque measurements in magnetic fields up to 10 T we have investigated the flux-creep rate and critical currents of three types of Y1Ba2Cu3O≈7-samples: ceramic bulk, triode sputtered films and ceramic foils (thickness 700 μm) consisting of superconducting grains embedded in a polymer. The highest Jc≌ 2. 106 A/cm2 is found for a 250 nm thick film sputtered on SrTiO with the c-axis perpendicular to the substrate. The creep-rate is strongly temperature dependent and is well described by a Kohlrausch behaviour (∝ exp −(t/t0)β with β ≅1/3.