Theory of Josephson effects in iron-based multi-gap superconductor junctions

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

Since the discovery of iron-based superconductors, Josephson junctions including such new materials have been intensively studied in order to explore their pairing symmetry and application potential. One of interesting features of this type of materials is the presence of multiple (more than two) bands on Fermi surface and their contributions to superconductivity. As a result, iron-based superconductor junctions are possible to have multiple tunneling channels between the superconducting electrodes. In this paper, we show a theory of Josephson junctions with multigap superconductors. We discuss how the relative fluctuations between multiple gaps and the pairing symmetry modify the Shapiro steps.