Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 8: Postersitzung I: Supraleitung

TT 8.10: Poster

Montag, 8. März 2004, 14:30–19:00, Poster A

Modifying the current distribution of grain boundaries — •Eva Brinkmeier, Harald Jarzina, Karsten Guth, Volker Born, and Christian Jooss — Institut fuer Materialphysik, Universitaet Goettingen, Tammanstrasse 1, 37077 Goettingen

The current distribution in thin superconducting films can be tailored by field conditioning via magnetic surroundings [1]. A soft magnet put parallel to a thin film edge can reduce or prevent the flux entry and therfor stabilise Meissner screening currents in the film. This is particularly interesting for the investigations of transport currents across grain boundaries in high temperature superconductors, where the critical current density sometimes strongly depends on the flux which penetrates into the grain boundary. Furthermore using special magnetic arrangements, asymmetric flux and current distributions can be tailored. We show, that flux penetration into grain boundary can be suppressed up to a certain external field H^*, which depends on the temperature and on the angle of the grain boundary.

All investigations were done by magneto-optical imaging and the inversion of Biot and Savart.

[1] H.Jarzina, Ch. Jooss and H.C. Freyhardt, J. Appl. Phys. 91 (2002) 3775