Rare-region onset of superconductivity in niobium nanoislands

We report measurements of the superconducting properties of isolated Nb nanoislands (600–2500 nm diameters) and explain their unusual behavior in terms of rare-region onset effects, predicted for random metal-superconductor granular systems [B. Spivak, P. Oreto, and S. A. Kivelson, Phys. Rev. B 77,...

Full description

Saved in:
Bibliographic Details
Published in:Physical review. B 2020-01, Vol.101 (3), p.1, Article 035409
Main Authors: Durkin, Malcolm, Garrido-Menacho, Rita, Gopalakrishnan, Sarang, Jaggi, Narendra K., Kwon, Ji-Hwan, Zuo, Jian-Min, Mason, Nadya
Format: Article
Language:English
Subjects:
Atomic force microscopy
Computer simulation
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Diameters
Electrons
Materials Science
Microscopy
Niobium
Physics
Superconductivity
Transition temperature
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We report measurements of the superconducting properties of isolated Nb nanoislands (600–2500 nm diameters) and explain their unusual behavior in terms of rare-region onset effects, predicted for random metal-superconductor granular systems [B. Spivak, P. Oreto, and S. A. Kivelson, Phys. Rev. B 77, 214523 (2008)]. We find that the island Tc is strongly suppressed even at large island diameters, exceeding 1 μm. This behavior is unexpected given that conventional theories of superconductivity in small grains predict suppression of Tc only at a length scale that is two orders of magnitude smaller. In addition, we observe large island-to-island variations in Tc for nominally identical islands. These two experimental observations, coupled with direct measurement of grain distribution using transmission electron microscopy, conductive atomic force microscopy, and computer simulations, provide evidence for our picture in which the onset of superconductivity on an island coincides with the transition temperature of its largest constituent grain, and then spreads to other grains due to proximity coupling.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.101.035409