title: Pi junction to probe antiphase s-wave pairing in iron pnictide superconductors.
abstract: Josephson junctions between a FeAs-based superconductor with antiphase s-wave pairing and a conventional s-wave superconductor are studied. The translational invariance in a planar junction between a single crystal pnictide and an aluminum metal greatly enhances the relative weight of electron pockets in the pnictide to the critical current. In a wide doping region of the pnictide, a planar and a point contact junction have opposite phases, which can be used to design a trijunction ring with pi phase to probe the antiphase pairing.
authors.affiliation: Department of Physics, and Center of Theoretical and Computational Physics, the University of Hong Kong, Hong Kong, China.
authors.forename: Wei-Qiang
authors.initials: WQ
authors.lastname: Chen
authors.forename: Fengjie
authors.initials: F
authors.lastname: Ma
authors.forename: Zhong-Yi
authors.initials: ZY
authors.lastname: Lu
authors.forename: Fu-Chun
authors.initials: FC
authors.lastname: Zhang