Anomalous critical supercurrent and half-integer Shapiro steps based on Josephson junction of topological insulator nanowires

Topological insulator-based Josephson junction, as a candidate device for searching Majorana zero energy modes, has attracted much attention. One of the key issues along this direction is to fabricate junctions with high-quality interfaces, hoping 4π-period current-phase relation in topologically non-trivial junction. In work, based on three-dimensional topological insulator nanowires Bi<sub>2</sub>Te<sub>3</sub> and Bi<sub>2</sub>(Se<sub><i>x</i></sub>Te<sub>1–<i>x</i></sub>)<sub>3</sub> are fabricated study their superconducting proximity effects, multiple Andreev reflections, relations. A number interesting phenomena observed, including anomalous enhancement junctions’ critical supercurrent magnetic field, appearance half-integer Shapiro steps ac effect. And, we discuss possible origins observed behaviors general, ferromagnetic layer TiTe alloy formed at interface between Ti buffer metallic electrodes, particular. We provide experimental evidence formation our device. believe that such breaks time reversal symmetry, leading well steps. Our results suggest relation, one still needs improve quality superconductor-normal metal-superconductor type junction devices.