Transport measurements in granular niobium nitride cermet films

Journal Article · Sat Aug 01 04:00:00 EDT 1987 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.36.1962· OSTI ID:6371098

Simon, R W; Dalrymple, B J; Van Vechten, D; Fuller, W W; Wolf, S A

We have studied normal-state and superconducting transport properties in a granular cermet consisting of B1-structure NbN grains in a boron nitride insulating matrix. By varying the volume fraction of the two components we produced films (20--70 nm in thickness) that exhibited transport behavior in either of two distinct and mutually exclusive classes: ''insulating'' films with rho--exp(-a/T/sup 1/2/) which never went superconducting, and ''superconducting'' films with rho--ln(T) from room temperature down to the superconducting transition. This latter logarithmic temperature dependence for the resistivity is also observed at low temperature when superconductivity is suppressed in high magnetic fields. Broad superconducting transitions are observed with a strong compositional dependence of the mean field critical temperature, T/sub c//sub 0/. The Kosterlitz-Thouless two-dimensional (2D) topological phase transition at T/sub 2D/ is observed in the superconducting samples both by the power-law behavior in current-voltage characteristics and by pure flux flow transport in high magnetic fields.

• Research Organization: Naval Research Laboratory, Washington, D.C. 20375
• OSTI ID: 6371098
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 36:4; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BORON COMPOUNDS
BORON NITRIDES
CERMETS
COMPOSITE MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FILMS
GRANULAR MATERIALS
MAGNETIC FIELDS
MATERIALS
MATRIX ISOLATION
MEAN-FIELD THEORY
NIOBIUM COMPOUNDS
NIOBIUM NITRIDES
NITRIDES
NITROGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PNICTIDES
QUANTITY RATIO
REFRACTORY METAL COMPOUNDS
SPUTTERING
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
ULTRAHIGH VACUUM