The role of the coherence length for the establishment of global phase coherence in arrays of ultra-thin superconducting nanowires. (23rd August 2017)

• Record Type: Journal Article
• Authors: Wong, Chi Ho; Lam, Frank L Y; Shen, Junying; He, Minquan; Hu, Xijun; Lortz, Rolf
• Is Part Of: Superconductor science & technology. Volume 30:Number 10(2017:Oct.)
• Publication Date: 2017-08-23
• Subjects: quasi-one-dimensional -- nanowire arrays -- dimensional crossover -- Josephson coupling; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/1361-6668/aa80d1
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: We have fabricated 5 nm ultra-thin NbN nanowires that form a dense and regular array in the linear channels of mesoporous SBA-15 silica substrates. Bulk NbN is a well-known classical superconductor with T c of 16 K. We show that, by being incorporated into this nanostructure, the composite material exhibits typical quasi-one-dimensional characteristics. We compare the superconducting properties with those of superconducting Pb nanowires of the same dimensionality in identical configuration within the linear SBA-15 pores. While Pb nanowire arrays show a pronounced crossover from 1D superconductivity at high temperatures to a 3D bulk superconducting state in the low-temperature regime with true zero resistance triggered by transversal Josephson interaction, this transition appears to be completely absent in the NbN nanowire array. The small coherence length in NbN, which strongly suppresses the Josephson coupling is discussed as the origin of this difference.