Thermodynamics of superconducting Nb/sub 3/Al, Nb/sub 3/Ge, Nb/sub 3/Sn, and V/sub 3/Ga

Journal Article · Fri Jun 01 00:00:00 EDT 1984 · Phys. Rev. B: Condens. Matter; (United States)

OSTI ID:6598615

Mitrovic, B; Schachinger, E; Carbotte, J P

We have calculated the superconducting thermodynamic properties for several high-transition-temperature A15 compounds: Nb-Al, Nb-Ge, Nb-Sn, and V-Ga. In our calculations we have used the tunneling electron-phonon--coupling spectra ..cap alpha../sup 2/F for all four systems considered, and in the case of Nb-Al and Nb-Ge we have also used ..cap alpha../sup 2/F = CG, where G is the measured generalized phonon density of states and C is a constant. We find that all Nb-based A15 compounds display similar thermodynamic properties, which do not depend explicitly on the band density of states: 2..delta../sub 0//k/sub B/T/sub c/approx. =4.6, ..delta..C/..gamma..T/sub c/approx. =2.5--2.6, -T/sub c/(dH/sub c/(T)/dT)c/ H/sub c/(0)approx. =2.1, ..gamma..(T/sub c//H/sub c/(0))/sup 2/approx. =0.134, and positive D(t)'s with the maximum value around 0.02. For Nb/sub 3/Sn we find good agreement between the calculated properties and the old specific-heat experimental results (..gamma..approx. =52 mJ/mol K/sup 2/). The same applies to V/sub 3/Ga, where the theoretical results have been compared with the experiments of Junod et al. However, we do not find good agreement between calculated ..delta..C/..gamma..T/sub c/, -T/sub c/(dH/sub c/(T)/dT)c/H/sub c/(0), ..gamma..(T/sub c//H/sub c/(0))/sup 2/, and experimental values for Nb/sub 3/Al and Nb/sub 3/Ge, presumably due to broadened transitions. It is argued that the tunneling experiments underestimate the value of the gap which should be associated with the inverted ..cap alpha../sup 2/F.

• Research Organization: Department of Physics, Brock University, St. Catharines, Ontario, Canada L2S 3A1
• OSTI ID: 6598615
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 29:11; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ALUMINIUM ALLOYS
BETA-W LATTICES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON-PHONON COUPLING
ENERGY-LEVEL DENSITY
GALLIUM ALLOYS
GERMANIUM ALLOYS
INTERMETALLIC COMPOUNDS
MATHEMATICAL MODELS
NIOBIUM ALLOYS
PARTICLE MODELS
PHYSICAL PROPERTIES
SPECIFIC HEAT
STRONG-COUPLING MODEL
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
TIN ALLOYS
TUNNEL EFFECT
VANADIUM ALLOYS