Superconductivity is inevitably suppressed in reduced dimensionality. Questions of how thin superconducting wires or films can be before they lose their superconducting properties have important technological ramifications and go to the heart of understanding coherence and robustness of the superconducting state in quantum-confined geometries. In this talk, I will show how quantum confinement of itinerant electrons in a soft metal, Pb, can be exploited to stabilize atomically smooth superconductors with lateral dimensions of the order of a few millimeters and vertical dimensions of only a few atomic layers. This non-classical growth mode is coined "electronic growth" or "quantum growth". These extremely thin superconductors show no indication of defect- or fluctuation-driven suppression of superconductivity and sustain enormous supercurrents of up to 10% of the theoretical depairing current density. Their magnetic hardness implies a superconducting critical state with strong vortex pinning that is attributed to quantum trapping of vortices. Our study paints a conceptually appealing, elegant picture of a model nanoscale superconductor with calculable critical state properties and surprisingly strong phase coherence. I will furthermore discuss how the superconductive properties of these films can be tailored by alloying or "Fermi surface engineering". This also includes the possibility of kinetically stabilizing metallic alloys of thermodynamically inmiscible elements through size quantization. Interesting implications for plasmon physics and chemical reactivity will also be discussed. This work was done in collaboration with M.M. Ozer, J.R. Thompson, Yu Jia, and Z.Y. Zhang.
M.M. Ozer et al., Science 316, 1594 (2007); Phys. Rev. B 74, 235427 (2006); and Nature Physics 2, 173 (2006)
Host: Robert Bartynski