Collective modes and Josephson vortices in a heterotic Josephson junction between single- and two-gap superconductors

Ota, Yukihiro; Machida, Masahiko  ; Koyama, Tomio*; Matsumoto, Hideki*

We construct a theory of a heterotic Josephson junction between single- and two-gap superconductors. The theory predicts the presence of in-phase and out-of-phase collective modes of superconducting phases. The former is the Josephson plasma mode, and the latter is a counterpart of Leggett's mode in Josephson junctions. A signature for -wave superconductivity is a drastic reduction of the frequency of the Josephson plasma mode. We also show that the magnetic field distribution of the Josephson vortex for -wave superconductivity is more enlarged than that for s-wave without sign change between the order parameters.