Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 28: Superconductivity: Heterostructures, Andreev Scattering, Proximity Effect, Coexistence

TT 28.9: Vortrag

Mittwoch, 25. März 2009, 17:45–18:00, HSZ 105

Superconductivity and Magnetism in Cuprate Heterostructures Studied by Low Energy µSR — •Bastian M. Wojek^1,2, Elvezio Morenzoni¹, Dmitry G. Eshchenko^1,2, Andreas Suter¹, Thomas Prokscha¹, Edmond Koller³, Emmanuel Treboux³, Øystein Fischer³, and Hugo Keller² — ¹Labor für Myonspinspektroskopie, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland — ²Physik-Institut der Universität Zürich, 8057 Zürich, Switzerland — ³DPMC, Université de Genève, 1211 Genève 4, Switzerland

Heterostructures consisting of magnetic/superconducting layers juxtaposed to each other are ideal systems to investigate the interplay of the two order parameters and to study possible interlayer coupling. Recently, so called giant proximity effects have been reported in Josephson devices consisting of HTS electrodes and a barrier of a cuprate in the pseudogap or AF state. Low energy µSR offers the unique possibility to measure on a nanometer scale local field distributions and identify superconducting and magnetic fractions. We used polarized low energy muons to investigate the local properties of single, bi- and tri-layers composed of superconducting YBa₂Cu₃O_7−δ and semiconducting PrBa₂Cu₃O_7−δ. Zero field measurements show that the PBCO layers (thickness 50-75 nm) display in all structures the known AF ordering. However, measurements of the field profile B(z) in the Meissner state show that below the critical temperature of YBCO, supercurrents flow without dissipation over the 50 nm thick AF barrier. The measurements indicate that a finite superfluid density may be induced in the AF layer adjacent to the superconducting layer.