Upper critical fields of periodic and quasiperiodic Nb-Ta superlattices

Journal Article · Mon Aug 01 00:00:00 EDT 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.38.2326· OSTI ID:6881446

Cohn, J L; Lin, J J; Lamelas, F J; He, H; Clarke, R; Uher, C

Upper critical fields have been studied for two series of Nb-Ta superlattices grown by molecular-beam epitaxy with both periodic and quasiperiodic (Fibonacci sequence) layering. X-ray results are presented to characterize the nature and quality of the layering. Positive curvature in the perpendicular upper critical field (H/sub c//sub 2//sub perpendicular/), pronounced negative curvature near T/sub c/ in the parallel upper critical field (H/sub c//sub 2//sub X/), and dimensional crossover are observed in both types of samples. For quasiperiodic samples two upturns are observed in H/sub c//sub 2//sub X/ with decreasing temperature. These are shown to be associated with dimensional crossover occurring twice as the superconducting coherence length in the growth direction, xi/sub perpendicular/, samples the two length scales, 2d/sub Nb/ and d/sub Nb/, that are present in these structures.

• Research Organization: Department of Physics, The University of Michigan, Ann Arbor, Michigan 48109
• OSTI ID: 6881446
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 38:4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
NIOBIUM
CRITICAL FIELD
SUPERCONDUCTIVITY
TANTALUM
MOLECULAR BEAM EPITAXY
MONOCRYSTALS
PROXIMITY EFFECT
SAPPHIRE
SUBSTRATES
SUPERLATTICES
TEMPERATURE DEPENDENCE
TYPE-II SUPERCONDUCTORS
ULTRAHIGH VACUUM
X-RAY DIFFRACTION
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COHERENT SCATTERING
CORUNDUM
CRYSTALS
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
EPITAXY
MAGNETIC FIELDS
METALS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SCATTERING
SUPERCONDUCTORS
TRANSITION ELEMENTS
360104* - Metals & Alloys- Physical Properties
656100 - Condensed Matter Physics- Superconductivity