Ambegaokar-Baratoff relations for Josephson critical current in heterojunctions with multigap superconductors

Yukihiro Ota, Noriyuki Nakai, Hiroki Nakamura, Masahiko Machida, Daisuke Inotani, Yoji Ohashi, Tomio Koyama, Hideki Matsumoto

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


An extension of the Ambegaokar-Baratoff relation to a superconductor- insulator-superconductor (SIS) Josephson junction with multiple tunneling channels is derived. Applying the resultant relation to a SIS Josephson junction formed by an iron-based (five-band) and a single-band Bardeen-Cooper-Schrieffer (BCS) type superconductors, a theoretical bound of the Josephson critical current (I c) multiplied by the resistance of the junction (R n) is given. We reveal that such a bound is useful for identifying the pairing symmetry of iron-pnictide superconductors. One finds that if a measured value of I c R n is smaller than the bound then the symmetry is ±s wave, and otherwise s wave without any sign changes. In addition, we stress that temperature dependence of I c R n is sensitive to the difference of the gap functions from the BCS type gap formula in the above heterojunction.

Original languageEnglish
Article number214511
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number21
Publication statusPublished - 2010 Jun 10

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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