Limits on Superconductivity in Nanoparticles and Nanowires

Recent experimental results are consistent with the prediction that superconductivity is suppressed in aluminum nanoparticles which are so small (10 nm diameter) that the electronic energy level spacing exceeds the superconducting energy gap in bulk material. Very recent experiments on nanowires (diameter 5–10 nm, length 150 nm) of MoGe indicate that a dissipative phase transition between superconducting and normal behavior occurs when the normal resistance of the wire equals the superconducting quantum resistance h/4e² 6.5 k.