Sputtered Nb/Ta multilayers: a quantitative study of superconducting properties

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5351668

Broussard, P R

Synthesis, structure, and superconducting properties of Nb/Ta multilayers are discussed. The multilayers were prepared by magnetron sputtering. X-ray diffraction was used to study the layering and structure of the samples. Longitudinal electrical-resistivity measurements were used to obtain the elastic mean free paths in the individual layers. Using the information on structure and mean free path, results of critical temperature, upper critical field, and critical current measurements were analyzed. The multilayers are found to grow epitaxially on sapphire substrates, but with substantially less dependence on substrate orientation or deposition temperature than has been previously seen. The system forms a coherent superlattice, with very little strain between the niobium and tantalum layers, as expected. The x-ray-diffraction profiles are identical to those of a mosaic crystal, indicating that the multilayers are well ordered. Electrical-resistivity measurements indicate that the samples are in the nearly clean to moderately dirty limit, in a superconducting sense. The results of superconducting critical-temperature measurements are analyzed in terms of the current proximity-effect theories. The measurements of upper critical field, both perpendicular and parallel to the direction of layering, are examined in light of the current models. Only qualitative agreement is found in each analysis due to the assumptions in the models.

• Research Organization: Stanford Univ., CA (USA)
• OSTI ID: 5351668
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104 -- Metals & Alloys-- Physical Properties
42 ENGINEERING
420800* -- Engineering-- Electronic Circuits & Devices-- (-1989)
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CORUNDUM
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
LAYERS
METALS
MINERALS
NIOBIUM
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SAPPHIRE
SPUTTERING
SUBSTRATES
SUPERCONDUCTIVITY
SUPERLATTICES
TANTALUM
TRANSITION ELEMENTS