The limits of superconductivity in MoGe nanowires

As the diameter of a superconducting wire is decreased to the order of the coherence length or less, the wire is no longer able to sustain the long range phase coherence and a non-zero resistance is measured. Based on the theory for quantum phase slips, we estimate that if the normal resistance of the wire is larger than 450 Omega per coherence length, the wire will stay resistive even at T much less than T-c. On the other hand, the localization effects may be weakening the superconductivity in the smallest wires due to enhanced Coulomb repulsion as the one-dimensional limit is approached. (C) 2003 Elsevier Science B.V. All rights reserved.