Electrical Step-Edge Contact to a Topological Superconductor Candidate 2M-WS₂

A topological superconductor (TSC), characterized by a topologically nontrivial bulk state and protected gapless boundary states, is a promising platform for hosting Majorana bound states. However, many TSCs are environmentally sensitive, especially when thinned to 2D atomic layers. This instability poses a major challenge for integrating TSCs into electronic devices. Addressing it requires full encapsulation and high-quality electrical contact to the TSC layer, which have not yet been achieved. Here, a novel contact geometry is demonstrated for an encapsulated topological superconductor candidate, 2M-WS₂, where metal electrodes contact the exposed step-like edges with a width of only a few nanometers. This structure yields exceptionally low contact resistance (R_C), down to ∼ 670 Ω·µm for a single unit and ∼ 65 Ω·µm for a six-unit 2M-WS₂ device. Below the superconducting critical temperature (T_C), the TSC-metal interface becomes highly transparent, as evidenced by the Andreev reflection. Furthermore, the step-edge contact prevents contamination during fabrication, enabling unprecedentedly high-quality devices. In encapsulated 2M-WS₂, twofold rotational symmetry of the critical current (I_C) and multiple anomalous peaks are observed in the differential resistance (dV/dI). The anisotropic I_C originates from Fermi velocity variations along in-plane lattice directions, while the anomalous peaks suggest multigap superconductivity in 2M-WS₂. These results reveal the intrinsic properties of 2M-WS₂ and offer a new path toward high-performance TSC-based electronics.