Extreme critical-temperature enhancement of Al by tunneling in Nb/AlO sub x /Al/AlO sub x /Nb tunnel junctions

Journal Article · Mon Jan 14 00:00:00 EST 1991 · Physical Review Letters; (USA)

DOI:https://doi.org/10.1103/PhysRevLett.66.220· OSTI ID:6118706

Blamire, M G; Kirk, E C.G.; Evetts, J E ^[1]; Klapwijk, T M ^[2]

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1. Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, United Kingdom (GB)
2. Department of Applied Physics, University of Groningen, Nijenborgh 18, 9747 AG Groningen, The Netherlands (NL)

High-conductance Nb/AlO{sub {ital x}}/Al/AlO{sub {ital x}}/Nb tunnel-junction devices with the Al thickness varying from 3 to 20 nm have been fabricated using a whole-wafer processing route. Current-voltage measurements show a step in the subgap structure corresponding to the difference in the energy gaps {ital V}=2({Delta}{sub Nb}{minus}{Delta}{sub Al}) of the two superconductors. The measured {Delta}{sub Al} is large and persists to temperatures considerably in excess of the equilibrium critical temperature of the Al. This is interpreted as arising from a tunnel-induced gap enhancement which is an order of magnitude larger than has been seen previously.

• OSTI ID: 6118706
• Journal Information: Physical Review Letters; (USA), Vol. 66:2; ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM
TRANSITION TEMPERATURE
TUNNEL EFFECT
ALUMINIUM OXIDES
NIOBIUM
SUPERCONDUCTING JUNCTIONS
AUGMENTATION
ELECTRIC CONDUCTIVITY
ENERGY GAP
EQUILIBRIUM
EXPERIMENTAL DATA
THICKNESS
ULTRALOW TEMPERATURE
ALUMINIUM COMPOUNDS
CHALCOGENIDES
DATA
DIMENSIONS
ELECTRICAL PROPERTIES
ELEMENTS
INFORMATION
JUNCTIONS
METALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
360104* - Metals & Alloys- Physical Properties
656100 - Condensed Matter Physics- Superconductivity