Coupling of two superconductors through a ferromagnet: evidence for a pi junction

V.V. Ryazanov, V.V. Oboznov, A.Yu. Rusanov, A.V. Veretennikov, Alexandre Avraamovitch Golubov, J. Aarts

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We report measurements of the temperature dependence of the critical current, Ic, in Josephson junctions consisting of conventional superconducting banks of Nb and a weakly ferromagnetic interlayer of a CuxNi1-x alloy, with x around 0.5. With decreasing temperature Ic generally increases, but for specific thicknesses of the ferromagnetic interlayer, a maximum is found followed by a strong decrease down to zero, after which Ic rises again. Such a sharp cusp can be explained only by assuming that the junction changes from a 0-phase state at high temperatures to a � phase state at low temperatures.
Original languageUndefined
Pages (from-to)2427-2430
Number of pages4
JournalPhysical review letters
Issue number11
Publication statusPublished - 2001


  • IR-61271
  • METIS-201139

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