Amorphous superconductor Zr/sub x/Cu/sub 1-x/: Electronic properties, stability, and low-energy excitations

Journal Article · Thu Jul 01 00:00:00 EDT 1982 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.26.107· OSTI ID:5036836

Samwer, K; Loehneysen, H v

Amorphous Zr/sub x/Cu/sub 1-x/ alloys (0.50< or =x< or =0.74) prepared by melt-spinning are investigated by means of electrical and thermal measurements. The negative temperature coefficient of the electrical resistivity suggests that the criterion 2k/sub F/roughly-equalk/sub p/ is always fulfilled in this system (k/sub F/ = Fermi wave number, k/sub p/ = position of the first maximum of the structure factor S(k)). The high density of states N/sub ..gamma../(E/sub F/) as inferred from specific-heat measurements originates from the d electrons of Zr. The bare density of states (determined from N/sub ..gamma../(E/sub F/) with the aid of the electron-phonon coupling constant lambda) is three times higher than calculated from the free-electron model and almost independent of the Zr concentration. Phonon-electron scattering as determined by thermal-conductivity measurements shows a similar deviation from free-electron behavior. A decisive test of the Nagel-Tauc condition for high (meta-) stability of the metallic glasses is not possible due to the apparent failure of both free-electron and rigid-band models. All samples investigated are superconducting and belong to the extreme-type-II superconductors. Fluctuation-induced paraconductivity extends up to 1.5T/sub c/. An analysis of the electron-phonon coupling constant lambda as determined from T/sub c/ indicates that the electron-ion matrix element varies strongly across the Zr/sub x/Cu/sub 1-x/ series. The size of lambda, the jump of the specific heat at T/sub c/, and its drop at low temperatures show that Zr-Cu alloys are weak- to intermediate-coupling superconductors. The relatively high T/sub c/ values of the Zr-rich metallic glasses allow the observation of a linear specific-heat term for T<

• Research Organization: I. Physikalisches Institut der Universitaet Goettingen, D-3400 Goettingen, West Germany
• OSTI ID: 5036836
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 26:1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COPPER ALLOYS
ELECTRICAL PROPERTIES
SUPERCONDUCTIVITY
ZIRCONIUM ALLOYS
AMORPHOUS STATE
ELECTRIC CONDUCTIVITY
ELECTRON-PHONON COUPLING
ENERGY-LEVEL DENSITY
EXPERIMENTAL DATA
SPECIFIC HEAT
STABILITY
TYPE-II SUPERCONDUCTORS
ALLOYS
DATA
INFORMATION
NUMERICAL DATA
PHYSICAL PROPERTIES
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
360104* - Metals &amp; Alloys- Physical Properties
656102 - Solid State Physics- Superconductivity- Acoustic
Electronic
Magnetic
Optical
&amp; Thermal Phenomena- (-1987)