Long Single Au Nanowires in Nb/Au/Nb Josephson Junctions: Implications for Superconducting Microelectronics

Abstract

The application of nanowires in superconducting electronic circuits is a prospective way to miniaturize conventional planar Josephson junctions. However, knowledge about nanowire-based devices’ fabrication technology and their performance at low temperatures is still scarce. Here, we propose a technique for obtaining long single Au nanowires and hybrid Josephson junctions formed by coupling the nanowires to planar Nb electrodes. The prospects for using electrodeposited Au nanowires with 30 and 60 nm diameters in superconducting microelectronics are illustrated by quantitative measurements of device current–voltage characteristics with weak link lengths varying from 280 to 520 nm at temperatures down to 1.2 K. The relationship between the nanowire structure and the electron transport properties of corresponding superconducting junctions is discussed. High critical current densities of Nb/Au-nanowire/Nb systems up to 1.6·106 A/cm2 combined with long-term stability make them promising candidates for the use in nanowire-based superconducting hybrid devices such as compact SQUIDs and superconducting neural networks with high integration density of circuits.