Specific heat of A 15 Nb/sub 3/Sn in fields to 18 tesla

Journal Article · Thu Oct 01 04:00:00 EDT 1981 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.24.3841· OSTI ID:5978027

Stewart, G R; Cort, B; Webb, G W

For the first time, the low-temperature specific heat of A 15 Nb/sub 3/Sn has been measured in a magnetic field (18 T) high enough to significantly suppress the superconducting transition temperature, T/sub c/. All previous extrapolations to T = 0 of the normal-state specific heat, C/sub n/, to determine ..gamma.. and N(0) are shown by the measured C/sub n/ data to be incorrect. The Debye temperature, O/sub D/, has previously been assumed to vary smoothly with temperature from its low-temperature value (theta/sub D/ (T<4 K) = 208 K) to its higher-temperature value (theta/sub D/(T>T/sub c/) = 270 K). The high-field measurement of theta/sub D/(T) shows that it remains constant upon cooling until 11 K, where it abruptly changes to its low-temperature value. The rather short extrapolation of the high-field normal-state data to T = 0 from T>T/sub c/(18 T) yields a ..gamma.. of 35 +- 3 mJ/mole K/sup 2/ compared to the previously accepted value of 52 mJ/mole K/sup 2/. Using this lower value for ..gamma.., and taking lambda = 1.75 from tunneling results, implies N(0) = 1.35 +- 0.1 states/eV atom in excellent agreement with recent band-structure calculations of Klein et al. who obtained 1.46 states/eV atom for A15 Nb/sub 3/Sn. The present work calls into question all other extrapolations of C/sub n/ data in high-T/sub c/ materials where THETA/sub D/ is known to change significantly between T/sub c/ and 0 K, e.g., A15 V/sub 3/Si.

• Research Organization: University of California, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
• OSTI ID: 5978027
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 24:7; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals &amp; Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
&amp; Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
BAND THEORY
BETA-W LATTICES
CALORIMETERS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DATA
DEBYE TEMPERATURE
ELECTRIC BRIDGES
ELECTRICAL EQUIPMENT
EQUIPMENT
EXPERIMENTAL DATA
INFORMATION
MAGNETIC FIELDS
MEASURING INSTRUMENTS
NIOBIUM ALLOYS
NOISE
NUMERICAL DATA
PHYSICAL PROPERTIES
POLYCRYSTALS
SPECIFIC HEAT
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TIN ALLOYS
TRANSITION TEMPERATURE
TYPE-II SUPERCONDUCTORS
ULTRALOW TEMPERATURE