Sign reversal of ac Josephson current in a ferromagnetic Josephson junction

Abstract

The ac Josephson effect in a ferromagnetic Josephson junction, which is composed of two superconductors separated by a ferromagnetic metal (FM), is studied by a tunneling Hamiltonian and Green's function method. We obtain two types of superconducting phase dependent current, i.e., Josephson current and quasiparticle-pair-interference current (QPIC). These currents change their signs with thickness of the FM layer due to the 0-$\pi$ transition characteristic to the ferromagnetic Josephson junction. As a function of applied voltage, the Josephson critical current shows a logarithmic divergence called the Riedel peak at the gap voltage, while the QPIC shows a discontinuous jump. The Riedel peak reverses due to the 0-$\pi$ transition and disappears near the 0-$\pi$ transition point. The discontinuous jump in the QPIC also represents similar behaviors to the Riedel peak. These results are in contrast to the conventional ones.

9 pages, 6 figures

References in corpus (5)

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• 0-pi Josephson tunnel junctions with ferromagnetic barrier
• FMR induced Josephson Current in a Superconductor/Ferromagnet/Superconductor Junction
• Role of magnetic scattering in 0-pi transitions in a superconductor/ferromagnetic metal/superconductor junction
• sin(2 phi) current-phase relation in SFS junctions with decoherence in the ferromagnet