Critical exponents of the superconducting transition in granular YBa2Cu3O7−δ

Abstract

We present the results of measurements designed to study superconducting I-V scaling in samples of polycrystalline YBa2Cu3O7−δ with varying mean grain sizes, 1 μm⩽〈dg〉⩽20 μm at selected magnetic fields, 0.5 G⩽H⩽10 T. I-V isotherm measurements performed near the superconducting transition on the samples are consistent with recent predictions of I-V scaling, with critical exponents ν∼1.1–1.75 and z∼2.3–4.3. The values for ν are comparable to those previously reported. The values for z are somewhat lower than what is predicted by the glassy models. The static exponent ν does not display any grain-size or magnetic-field dependence. The dynamic exponent, however, does display some morphology dependence with z higher for the small grain-size samples. The data shows some evidence for a crossover between low and high z values in increasing magnetic fields.

Source-reported materials — not catalogue approval

Similar papers