Dichotomy in short superconducting nanowires: Thermal phase slippage vs. Coulomb blockade

Department of Physics, University of Illinois at Urbana-Champaign Urbana, IL 61801-3080, USA

Corresponding author: bezryadi@uiuc.edu

Received: 12 May 2006
Accepted: 4 September 2006

Abstract

Quasi-one-dimensional superconductors or nanowires exhibit a transition into a nonsuperconducting regime, as their diameter shrinks. We present measurements on ultrashort nanowires (~40–190 long) in the vicinity of this quantum transition. Properties of all wires in the superconducting phase, even those close to the transition, can be explained in terms of thermally activated phase slips. The behavior of nanowires in the nonsuperconducting phase agrees with the theories of the Coulomb blockade of coherent transport through mesoscopic normal metal conductors. Thus it is concluded that the quantum transition occurs between two phases: a “true superconducting phase" and an “insulating phase". No intermediate, “metallic" phase was found.