Ultrasonic Attenuation in Superconducting Molybdenum
Journal Article
·
· Physical Review, B: Solid State
Measurements have been made on the attenuation of 10-, 30-, and 50-MHz longitudinal sound waves in normal amd superconducting molybdenum single crystals. These measurements were made for the ultrasound propagated in the [100], [110], and [111] directions. The measured attenuation changes have been analyzed in terms of the BCS theory of superconductivity. An effective minimum energy gap has been determined and has been found to be anistropic. We have also observed a frequency-dependent behavior in the measured values of the ratio of the ultrasonic attenuation in the superconducting state over that in the normal state alpha a/ alpha n hence in the values of the energy gap DELTA (T), calculated by fitting the data to the BCS model. Superconducting properties and electrical resistivities of NbN thin films have been studied as a function of sputtering parameters, film structure, and composition. A good correlation exists between superconducting Tc,'s and film structure and composition regardless of the sputtering conditions used to achieve this structure. The most important parameters affecting Tc are lattice parameter, crystal structure island structure, and impurity content. Substrate temperature, Ar/N2 ratio, and impurity content are the prindipal sputtering parameters affecting film structure, and thus Tc.
- Research Organization:
- Department of Physics, Texas Tech University, Lubbock, Texas 79409
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-022760
- OSTI ID:
- 4315206
- Journal Information:
- Physical Review, B: Solid State, Journal Name: Physical Review, B: Solid State Journal Issue: 9 Vol. 8; ISSN 0556-2805; ISSN PRBMDO
- Country of Publication:
- United States
- Language:
- English
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