Regensburg 2004 – scientific programme

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TT: Tiefe Temperaturen

TT 31: Supraleitung: Vortexdynamik, Vortexphasen, Pinning

TT 31.6: Talk

Friday, March 12, 2004, 11:30–11:45, H20

Vortex matter phase diagram of pure and Zn-doped YBa₂Cu₃O_7−x in magnetic fields up to 50 T — •Yurii Skourski^1,2, Günter Fuchs¹, Nadezhda Kozlova¹, Konstantin Nenkov¹, Gernot Krabbes¹, and Karl-Hartmut Müller¹ — ¹Leibniz Institut für Festkörper- und Werkstoffforschung Dresden, P.O. Box 270016, D-01171 — ²Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Strasse 38, 01187 Dresden

The vortex matter phase diagram of melt textured YBa₂Cu₃O_7−x (YBCO) and of Zn doped YBCO was investigated by magnetization and resistance measurements in magnetic fields up to 50 T. Data for the irreversibility field H_irr(T) and the upper critical field H_c2(T) obtained in pulsed and static fields show a good agreement. A strong suppression of the superconducting transition temperature by about 15 K was observed for a YBCO sample doped with 1.2%Zn. In addition, the shape of H_irr(T) and H_c2(T) was found to be strongly affected by Zn doping. Consequently, the transition from the vortex glass to the vortex liquid phase found for undoped YBCO is shifted to lower magnetic fields for Zn doped YBCO. The experimental data are compared with the predictions of existing models.