Transport properties of YBa2Cu3O7-δthin films near the critical state with no applied magnetic field

• Published in: Physica. C, Superconductivity Superconductivity, 2008-02, Vol.468 (3), p.200-209
• Main Authors: BERNSTEIN, P, HAMET, J. F, THIMONT, Y
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Critical currents; Exact sciences and technology; Physics; Properties of type I and type II superconductors; Proximity effects, weak links, tunneling phenomena, and josephson effects, adreev effect, sn and sns junctions; Superconductivity
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/j.physc.2007.11.004

Transport measurements carried out on twinned YBa2Cu3O7-delta films are compared to the predictions of a previously proposed model suggesting that the vortices move along the films twin boundaries that behave as rows of Josephson weak links [P. Bernstein, J.F. Hamet, J. Appl. Phys. 95 (2004) 2569]. The obtained results suggest that, except if the films are very thin, the twin boundaries consist of superimposed rows of weak links with mean height, , whose mean length along the TBs is an universal function of T/Tc, the reduced temperature. This conclusion yields a general expression for the critical surface current density of the films as a function of T/Tc and of the number of superimposed weak links rows, while the critical current density depends on . A comparison of the measurements reported by various authors shows that the nature of the substrate and the growth technique have both a strong effect on . The existence of superimposed weak links rows is attributed to extended defects generated by Y2O3 inclusions.