Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 33: Superconductivity: Vortex Dynamics, Vortex Phases, Pinning
TT 33.5: Vortrag
Freitag, 31. März 2006, 11:15–11:30, HSZ 304
Overcritical currents across grain boundaries in YBaCuO thin films — •Christian Jooss1, Eva Brinkmeier1, and Harald Heese2 — 1Institut für Materialphysik, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — 2Institut für Numerische Mathematik, University of Göttingen, Germany
The current distribution in thin superconducting films can be strongly modified by the presence of soft magnetic environments. A soft magnet put parallel to a thin film edge can reduce or completely prevent flux entry and therefore stabilize Meissner screening currents in the film. This effect is of particular importance for the modification of the current distributions across grain boundaries in high-Tc superconductors, where the intergranular critical current density strongly depends on the flux which penetrates into the grain boundary. Furthermore, using special magnetic arrangements, asymmetric flux and current distributions can be obtained. An increase of the grain boundary critical current is obtained in the Meissner state, compared to the flux penetrated states [1]. The experimental studies via quantitative magneto-optical imaging are combined with theoretical calculations of the flux and current density distributions of superconducting strips in magnetic environments of arbitrary shape. The theoretical simulations are obtained by considering a boundary value problem for the Laplace equation as a mathematical model, which is then treated via integral equation methods.
[1] Ch. Jooss, E. Brinkmeier and H. Heese, Phys. Rev. B 72 (2005) 144516.