Theory of vortex structure in Josephson junctions with multiple tunneling channels: Vortex enlargement as a probe of±s-wave superconductivity

Abstract

We theoretically study Josephson vortex structures in Josephson junctions which have multiple tunneling channels caused by multiple superconducting gaps. Deriving ``coupled sine-Gordon equations'' from the free-energy taking account of the multiple tunneling channels, we examine two typical situations, a heterotic junction composed of multigap-superconductor, insulator, and single-gap superconductor, and a grain-boundary junction formed by two identical multigap superconductors. Then, we reveal in both situations that the magnetic field distribution of the Josephson vortex for $\ifmmode\pm\else\textpm\fi{}s$-wave superconductivity is more enlarged than that for $s$ wave without sign change between the order parameters. Its mechanism is ascribed to a cancellation of the multiple Josephson currents. We display such an anomalous Josephson vortex and suggest how to evaluate the enlargement.