Vortex Diode Effect in Pinning Enhanced Thin Films

John H. Durrell, Sophie A. Harrington, R. Dinner, M. G. Blamire,
Judith L. MacManus-Driscoll, J. H. Lee, Haiyan Wang

Abstract — The critical current anisotropy in the cuprate superconductor YBCO arises due to a number of different sources. We have found that the contribution of geometric effects, essentially due to surface pinning, cannot be neglected in YBCO films with pinning enhanced through the introduction of a second phase. We show a significant variation in critical current when the direction of the Lorentz force is reversed. We associate this effect with the substrate/film interface consisting of a region of graded superconductivity. Finally we point out the importance of measuring the full angular range of field when characterizing the critical current anisotropy of YBCO.

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