Long-range skin Josephson supercurrent across a van der Waals ferromagnet

When entering a ferromagnet, a spin-singlet supercurrent decays rapidly, while a spin-triplet supercurrent can extend over much longer distances. Here, the authors observe long-range, spin triplet supercurrent in lateral Josephson junctions constructed using the van der Waals metallic ferromagnet Fe3GeTe2 as the weak link. The emerging field of superconducting spintronics promises new quantum device architectures without energy dissipation. When entering a ferromagnet, a supercurrent commonly behaves as a spin singlet that decays rapidly; in contrast, a spin-triplet supercurrent can transport over much longer distances, and is therefore more desirable, but so far has been observed much less frequently. Here, by using the van der Waals ferromagnet Fe3GeTe2 (F) and spin-singlet superconductor NbSe2 (S), we construct lateral Josephson junctions of S/F/S with accurate interface control to realize long-range skin supercurrent. The observed supercurrent across the ferromagnet can extend over 300 nm, and exhibits distinct quantum interference patterns in an external magnetic field. Strikingly, the supercurrent displays pronounced skin characteristics, with its density peaked at the surfaces or edges of the ferromagnet. Our central findings shed new light on the convergence of superconductivity and spintronics based on two-dimensional materials.