Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 25: FV-internes Symposium ”Superconducting Qubits and π-junctions”
TT 25.6: Hauptvortrag
Donnerstag, 11. März 2004, 12:15–12:45, H20
π-superconductivity in S/F nano-structures — •Marco Aprili1,2, T. Kontos1, W. Guichard3, ML. Della Rocca1,2, J. Lesueur2, and P. Gandit3 — 1CSNSM-CNRS, Bat.108 Université Paris-Sud, 91400 Orsay, France — 2Laboratoire de Physique Quantique ESPCI, 10 rue Vauquelin, 75005 Paris, France — 3CRTBT-CNRS, 25 Avenue des Martyrs, 38000 Grenoble, France
Hybrid nanostructures not only open new routes for studying the coexistence between superconductivity and ferromagnetism, but they also provide new insights to fundamentals of quantum electronics. We have investigated the change in the superconducting wavefunction resulting from the interaction between the spins of a Cooper pair and the exchange field. Tunnelling spectroscopy reveals an inhomogeneous superconducting state induced in a ferromagnetic thin film by the proximity effect. As a consequence, critical current and macroscopic quantum interference experiments show π-coupling when the ferromagnetic thin film is coupled with a second superconductor. π-coupling originates a spontaneous half quantum flux in a superconducting ring. This phase transition has been recently observed by SQUID and Hall magnetometry (Regensburg-Orsay experiment).