Theoretical study of ac Josephson effect in a double barrier Josephson junction

S. Hikino, M. Mori, S. Takahashi, S. Maekawa

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1 Citation (Scopus)

Abstract

We study an ac Josephson effect in a SC/I/X/I/SC junction, where SC is an s-wave superconductor, I is an insulator, and X is either a normal metal (NM) or a ferromagnetic metal (FM). Using a tunneling Hamiltonian and Green's function method, we obtain two types of superconducting phase dependent current. One is the Josephson current and the other is the quasiparticle-pair-interference current (QPIC). In a SC/I/NM/I/SC junction, the Josephson critical current (Ic 1) and the amplitude of QPIC (Ic2) are functions of the thickness of NM and the applied voltage (V). Ic1 shows a logarithmic divergence called Riedel peak at the gap voltage, V = 2 Δ / e, where Δ is the superconducting gap, and Ic2 shows a discontinuous jump at the gap voltage. These behaviors are similar to these of SC/I/SC junctions. On the other hand, in a SC/I/FM/I/SC junction, Ic1 and Ic2 exhibit the strong dependence on the thickness of FM and changes their signs by crossing the 0-π transition point due to the magnetic exchange splitting between the up- and down-spin bands in FM. It is predicted that the Riedel peak in Ic1 disappears at the 0-π transition and the 0-π transition occurs in Ic2 similarly to Ic1.

Original languageEnglish
Pages (from-to)1907-1909
Number of pages3
JournalPhysica C: Superconductivity and its applications
Volume468
Issue number15-20
DOIs
Publication statusPublished - 2008 Sep 15

Keywords

  • Ferromagnet
  • Nanostructure
  • Superconductor
  • Tunnel junction
  • ac Josephson effect

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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