Using the functional integral method, we construct a theory of heterotic SIS Josephson junctions between single- and two-gap superconductors. The theory predicts the presence of in-phase and out-of-phase collective oscillation modes of superconducting phases. The former corresponds to the Josephson plasma mode whose frequency is drastically reduced for ± s-wave symmetry, and the latter is a counterpart of Leggett's mode in Josephson junctions. We also reveal that the critical current and the Fraunhofer pattern strongly depend on the symmetry type of the two-gap superconductor.
@article{arxiv.0903.0421,
title = {Theory of heterotic SIS Josephson junctions between single- and multi-gap superconductors},
author = {Yukihiro Ota and Masahiko Machida and Tomio Koyama and Hideki Matsumoto},
journal= {arXiv preprint arXiv:0903.0421},
year = {2009}
}