title: Reentrant Phase Coherence in Superconducting Nanowire Composites.
abstract: The short coherence lengths characteristic of low-dimensional superconductors are associated with usefully high critical fields or temperatures. Unfortunately, such materials are often sensitive to disorder and suffer from phase fluctuations in the superconducting order parameter which diverge with temperature T, magnetic field H, or current I. We propose an approach to overcome synthesis and fluctuation problems: building superconductors from inhomogeneous composites of nanofilaments. Macroscopic crystals of quasi-one-dimensional Na2-δMo6Se6 featuring Na vacancy disorder (δ ≈ 0.2) are shown to behave as percolative networks of superconducting nanowires. Long-range order is established via transverse coupling between individual one-dimensional filaments, yet phase coherence remains unstable to fluctuations and localization in the zero (T,H,I) limit. However, a region of reentrant phase coherence develops upon raising (T,H,I). We attribute this phenomenon to an enhancement of the transverse coupling due to electron delocalization. Our observations of reentrant phase coherence coincide with a peak in the Josephson energy EJ at nonzero (T,H,I), which we estimate using a simple analytical model for a disordered anisotropic superconductor. Na2-δMo6Se6 is therefore a blueprint for a future generation of nanofilamentary superconductors with inbuilt resilience to phase fluctuations at elevated (T,H,I).
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 637371 Singapore.
authors.forename: Diane
authors.initials: D
authors.lastname: Ansermet
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 637371 Singapore.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Petrović
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 637371 Singapore.
authors.forename: Shikun
authors.initials: S
authors.lastname: He
authors.affiliation: Swiss-Norwegian Beamline, European Synchrotron Radiation Facility , 6 rue Jules Horowitz, Grenoble F-38043 Cedex, France.
authors.forename: Dmitri
authors.initials: D
authors.lastname: Chernyshov
authors.affiliation: Diamond Light Source , Harwell Campus, Didcot OX11 0DE, Oxfordshire, United Kingdom.
authors.forename: Moritz
authors.initials: M
authors.lastname: Hoesch
authors.affiliation: Sciences Chimiques, CSM UMR CNRS 6226, Université de Rennes 1 , Avenue du Général Leclerc, Rennes 35042 Cedex, France.|Faculty of Science III, Lebanese University , P.O. Box 826, Kobbeh-Tripoli, Lebanon.
authors.forename: Diala
authors.initials: D
authors.lastname: Salloum
authors.affiliation: Sciences Chimiques, CSM UMR CNRS 6226, Université de Rennes 1 , Avenue du Général Leclerc, Rennes 35042 Cedex, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Gougeon
authors.affiliation: Sciences Chimiques, CSM UMR CNRS 6226, Université de Rennes 1 , Avenue du Général Leclerc, Rennes 35042 Cedex, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Potel
authors.affiliation: Institute for Theoretical and Computational Physics, TU Graz , Petersgasse 16, 8010 Graz, Austria.
authors.forename: Lilia
authors.initials: L
authors.lastname: Boeri
authors.affiliation: Max Planck Institute for Solid State Research , Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
authors.forename: Ole Krogh
authors.initials: OK
authors.lastname: Andersen
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 637371 Singapore.
authors.forename: Christos
authors.initials: C
authors.lastname: Panagopoulos
keywords: nanofilaments; quasi-one-dimensional; reentrance; superconductivity