Anomalously high 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 supercurrent. 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 a two-dimensional superconductor. The compound 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 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 establishes it as a topological superconductor candidate, which is promising for the development of quantum computing technology.