Annealing effects on the sound velocity and internal friction in the superconducting and normal states of the Cu/sub 30/Zr/sub 70/ amorphous alloy

Journal Article · Sun May 01 04:00:00 EDT 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.37.7819· OSTI ID:5222780

Esquinazi, P; Luzuriaga, J

By means of the vibrating-reed technique we have measured the evolution upon low-temperature annealing of the internal friction Q/sup -1/ and sound velocity v of the Cu/sub 30/Zr/sub 70/ amorphous alloy between 0.1 and 10 K. With an applied magnetic field of 5.6 T we measured also the normal-state behavior of both properties. Upon annealing, the internal friction and the slope of the logarithmic temperature dependence of v in the superconducting state decrease, in agreement with the standard tunneling model. Our results indicate that with thermal treatments, the coupling constant between tunneling systems (TS's) and phonons decreases, and the density of states of the TS remains constant or decreases, at most 25%, in the fully relaxed state, which is in agreement with published specific-heat results in these materials. From our data we conclude that the coupling constant between the TS and phonons should be very sensitive to the relaxed state of the disordered structure. The sound-velocity behavior strongly indicates that relaxation processes up to 10 K involve the interaction with the TS. A well-defined change of slope in v at the superconducting critical temperature T/sub c/ is observed in the as-quenched and the first relaxed state, which cannot be explained with the standard tunneling model and the Korringa-like relaxation rate between the TS and electrons. Several features observed in the superconducting and normal states lead to the conclusion that the TS-electron interaction problem remains unsolved

• Research Organization: Centro Atomico Bariloche, Instituto Balseiro, 8400 Bariloche, Argentina
• OSTI ID: 5222780
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 37:13; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
360104 -- Metals & Alloys-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACOUSTIC MEASUREMENTS
ALLOYS
AMORPHOUS STATE
ANNEALING
COPPER ALLOYS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON-PHONON COUPLING
ENERGY-LEVEL DENSITY
FRICTION
HEAT TREATMENTS
INTERNAL FRICTION
PHYSICAL PROPERTIES
RELAXATION
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
ULTRALOW TEMPERATURE
ZIRCONIUM ALLOYS