Prepatterned Superconducting Contacts for Clean Superconductor-Topological Material Interfaces Enabling Long-Range Josephson Coupling.

Phase-coherent superconducting proximity in topological materials (TMs) requires clean superconductor-topological material (SC-TM) interfaces, yet conventional top-contact fabrication often degrades them through oxidation, polymer residue, and process-induced disorder. Here we introduce a prepatterned superconducting bottom-contact architecture in which MoRe/Au electrodes are defined before van der Waals (vdW) crystal transfer, thereby avoiding on-flake lithography after transfer. In WTe2- and Bi1.5Sb0.5Te1.7Se1.3-based Josephson junctions, this architecture yields systematically larger IcRN and longer-ranged coupling than conventional top contacts. Cross-sectional scanning transmission electron microscopy/energy-dispersive spectroscopy reveals atomically abrupt, chemically well-separated interfaces. These results establish prepatterned SC-TM contacts as a practical route to reproducible, micrometer-scale Josephson platforms in vdW TMs.