Boundary effect on superconductivity in long single-crystal superconducting nanowires

Abstract: We fabricate single-crystal Pb, Sn, and Zn nanowires, of length 6 or 60μm and diameter 30–250nm, using an in situ template-based electrochemical method. In this approach, a single nanowire is formed in contact with a pair of bulk film electrodes of Au, Sn, or Pb. We observe that, with superconducting electrodes having a higher critical temperature T c , superconductivity is induced in Sn and Zn nanowires at the T c of the electrodes for nanowires as long as 60μm. With Au electrodes, superconductivity is suppressed completely in 6μm-long nanowires and partially in 60μm-long nanowires. Based on transmission electron microscopy studies, the nanowires are single crystalline. Analysis of the temperature dependence of the normalized resistance suggests that the residual-resistance-ratio plays an important role in the observed anomalous long-range proximity effect. [Copyright &y& Elsevier]