The World’s Thinnest Superconductor

Abstract

Conventional wisdom suggests that superconductivity should be suppressed in low-dimensional geometries such as ultrathin films or quantum wires due to thermodynamic fluctuations, proximity effects, scattering, and the corresponding breaking of Cooper pairs. Exactly how thin a wire or film should be before superconductivity is lost is a very important consideration for applications in nanotechnology. From the physicist’s perspective, this question goes to the heart of understanding coherence and robustness of the superconducting state in quantum-mechanically confined geometries. However, systematic investigations of these phenomena have been hampered by insufficient quality control of the samples.