Ultrahigh supercurrent density in a two-dimensional topological material

Ongoing advances in superconductors continue to revolutionize technology thanks to the increasingly versatile and robust availability of lossless supercurrents. In particular, high supercurrent density can lead to more efficient and compact power transmission lines, high-field magnets, as well as high-performance nanoscale radiation detectors and superconducting spintronics. Here, we report the discovery of an unprecedentedly high superconducting critical current density (17 MA/cm² at 0 T and 7 MA/cm² at 8 T) in 1T′-WS₂, exceeding those of all reported two-dimensional superconductors to date. 1T′-WS₂ features a strongly anisotropic (both in- and out-of-plane) superconducting state that violates the Pauli paramagnetic limit signaling the presence of unconventional superconductivity. Spectroscopic imaging of the vortices further substantiates the anisotropic nature of the superconducting state. More intriguingly, the normal state of 1T′-WS₂ carries topological properties. The band structure obtained via angle-resolved photoemission spectroscopy and first-principles calculations points to a Z₂ topological invariant. The concomitance of topology and superconductivity in 1T′-WS₂ establishes it as a topological superconductor candidate, which is promising for the development of quantum computing technology. © 2023 American Physical Society.