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TT: Fachverband Tiefe Temperaturen

TT 32: Postersession Superconductivity: Josephson Junctions, SQUIDs, Heterostructures, Andreev Scattering, Vortex Physics, Cryodetectors, Measuring Devices, Cryotechnique

TT 32.21: Poster

Mittwoch, 25. März 2009, 14:00–18:00, P1A

Behavior of the vortex-creep activation energy in YBa₂Cu₃O_7−δ/PrBa₂Cu₃O_7−δ superlattices — •Ayman El Tahan¹, Lucica Miu², Gerhard Jakob¹, and Hermann Adrian¹ — ¹Institute of Physics, University of Mainz, 55099 Mainz, Germany — ²National Institute of Materials Physics, 77125 Bucharest, Romania

YBa₂Cu₃O_7−δ/PrBa₂Cu₃O_7−δ (YBCO/PBCO) superlattices with a different ratio of the superconducting and insulating layer thicknesses were prepared by high-pressure dc sputtering. The vortex-creep activation energy U was determined by analyzing the in-plane resistive transition of 200 µm- and 10 µm-wide bridges with the external magnetic field B oriented along the c axis. We found that U is proportional to the thickness of YBCO, and does not depend on the PBCO thickness, when the latter exceeds two unit cells. The U(B) dependence is well described by U(B) ∝ B^(1/2). The observed behavior can be explained in terms of 2D collective pinning. Financial support by the MWFZ Mainz, the Humboldt foundation, and the government of Egypt is gratefully acknowledged.