Superconductivity and structure of NbN/AlN multilayers

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5525001

Murduck, J M

Multilayers of niobium nitride and aluminum nitride (NbN/AlN) are fabricated as a method to enhance the high-field superconducting properties of NbN. NbN is of interest as a candidate for magnet applications involving fusion because of its excellent high-field transport properties and its tolerance to radiation and strain. Films are prepared by reactive d.c. magnetron sputtering and are shown to be well-layered superlattices by x-ray diffraction and electron microscopy. For films < 140 {angstroms}, the parallel critical fields are observed to increase with decreasing NbN layer thicknesses in good agreement with 2D Ginzburg-Landau theory. For some range of NbN thicknesses, a dramatic increase in J{sub c} is observed; the enhancement is more than an order of magnitude greater than thick NbN films. It is argued that the J{sub c} enhancement arises from flux pinning in the AlN, or at the AlN/NbN interface, but not on defects in the NbN structure. Disorder is shown to exist within the NbN but primarily only for NbN layer thicknesses less than 60 {angstrom}, as seen by transport properties and structural characterizations, and does not explain enhanced flux pinning for larger NbN thickness. Unlike thick NbN films, the flux pinning density is greater in the parallel rather than perpendicular field direction.

• Research Organization: Northwestern Univ., Evanston, IL (USA)
• OSTI ID: 5525001
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
&amp; Refractories-- Structure &amp; Phase Studies
360204* -- Ceramics
Cermets
&amp; Refractories-- Physical Properties
420201 -- Engineering-- Cryogenic Equipment &amp; Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALUMINIUM COMPOUNDS
ALUMINIUM NITRIDES
DIMENSIONS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FILMS
MAGNETIC FLUX
NIOBIUM COMPOUNDS
NIOBIUM NITRIDES
NITRIDES
NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
PNICTIDES
REFRACTORY METAL COMPOUNDS
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
THICKNESS
THIN FILMS
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE