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VOLUME 75 (2002) | ISSUE 4 |
PAGE 228
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Angular dependence of the upper critical field in Bi2Sr2CuO6+δ
S. I. Vedeneev+*, Yu. N. Ovchinnikov
+P. N. Lebedev Physical Institute RAS, 117924 Moscow, Russia *Grenoble High Magnetic Field Laboratory, Max-Planck-Institut für Festkörperforschung and Centre National de la Recherche Scientifique, F-38042 Grenoble, France L. D. Landau Institute for Theoretical Physics RAS, 117940 Moscow, Russia Centre de Recherches sur les Très Basses Températures, Centre National de la Recherche Scientifique, F-38042 Grenoble, France
PACS: 74.25.Ha, 74.60.Ec, 74.72.Hs
Abstract
The angular dependence of the upper critical magnetic field has been
investigated in a wide range of temperatures in very high-quality Bi2Sr 2CuO6+δ single crystals with critical temperature Tc
(midpoint) K in magnetic fields up to 28 T. Although the typical
value of the normal state resistivity ratio
, the anisotropy ratio / of the upper critical fields is much smaller and shows an unexpected
temperature dependence. A model is proposed based on a strong anisotropy and
a small transparency between superconducting layers.
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