Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 2: Superconductivity: Conductor Development
TT 2.3: Vortrag
Montag, 27. März 2006, 12:00–12:15, HSZ 02
Grain boundaries in REBaCuO (RE=Er,Y,Yb) Ca-doped YBaCuO thin films: Mechanisms of current suppression and current enhancement — •Christian Jooss1, Karsten Guth2, Yimei Zhu3, and Felip Sandiumenge4 — 1Institute of Materials Physics, University of Goettingen, Germany — 2EUPEC GmbH — 3Brookhaven National Laboratory, Upton NY 11973, USA — 4CSIC, Universitat Autonoma de Barcelona, Spain
Recent results on low-angle grain boundaries in high-temperature superconductors give fascinating insight into their interplay of atomic structure, electronic properties and transport properties [1,2]. It was shown that Ca doping can reduce atomic strain and the related size of space charge layers and therefore can significantly improve the transport properties in a wide angular range. However, our experimental data suggests that this mechanism does not work for all types of grain boundaries. Furthermore, we present experiments on ErBaCuO and YbBaCuO bi-crystalline films, where charge balance arguments suggests an increased hole density in the electronic conduction bands and, in the framework of specific models, an increased critical current density. The different types of experiments will be summarized to determine the atomic mechanism determining the grain boundary transport properties. [1] R. F. Klie, J. P. Buban, M. Varela, A. Franceschetti, C. Jooss, Y. Zhu, N. D. Browning, S. T. Pantelides, S. J. Pennycook, Nature 435 (2005) 475. [2] M. A. Schofield, M. Beleggia, Y. Zhu, K. Guth, Ch. Jooss, Phys. Rev. Lett. 92 (2004) 195502