Regensburg 2000 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 14: Wachstum und Transport in dünnen Filmen

TT 14.6: Vortrag

Mittwoch, 29. März 2000, 16:00–16:15, H19

Measurements of the Penetration Depth in both the Meissner and the Mixed States of an YBa₂Cu₃O_7−δ Thin Film with Low Energy Muons — •M. Pleines¹, Ch. Niedermayer¹, G. Schatz¹, T.J. Jackson², T.M. Riseman², E.M. Forgan², H. Glückler³, T. Prokscha³, E. Morenzoni³, M. Birke⁴, H. Luetkens⁴, and J. Litterst⁴ — ¹Fakultät für Physik, Universität Konstanz, D-78457 Konstanz — ²School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom — ³Labor für Myonspinspektroskopie, Paul Scherrer Institut, CH-5232 Villigen PSI — ⁴IMNF, TU Braunschweig, D-38106 Braunscheig

We have used the low energy µSR (LE-µSR) technique to study the magnetic penetration depth (λ) in a thin superconducting film with tunable implantation depths in the range of 15 - 150 nm. λ is the lenght scale over which the magnetic field decays exponentially in a superconductor, either from its surface (in the Meissner state) or from its vortices (in the mixed state). In one experiment the external field was applied parallel to the surface of the thin film in the Meissner state. Here, the exponential decay is observed directly by varying the the implantation depth. In the other experiment the field was applied perpendicular to the surface, so that a vortex lattice was formed. The vortices splay out in the region of the superconducting surface of the superconductor, until a uniform field is recovered at some distance outside the film. This regime is inaccessible for conventional µSR measurements.