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Publications and source records attributed to Kammerdiner, L..
Critical currents in sputtered Chevrel-phase lead molybdenum sulfide have been measured at several temperatures as a function of applied magnetic field up to 19 T. A critical current density of approximately 50 million A/sq m was obtained at 15 T and 1.8 K, and the effective upper critical field was estimated to be 30 T. The pinning force at low fields was found to be dependent on the amount of free lead.
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Critical currents in a sputtered Chevrel-phase copper molybdenum sulfide have been measured at 4.2 K as a function of applied magnetic field. Self-field critical-current values up to 10 to the 9th A/sq m were found, decreasing to 10 to the 8th A/sq m at 3 T. Graphs of pinning forces versus field were found to be independent of field direction, and the pinning mechanism is sample independent. Critical-current densities for sputtered lead molybdenum sulphide are estimated to be about 10 to the 8th A/sq m at 26 T based on a scaling law for pinning.
The superconducting transition temperature and the superconducting upper critical fields for sputtered films of copper-containing ternary molybdenum chalcogenides (chevrel phases) were determined. The theory presented by Werthamer, Helfand, and Hohenberg (WHH) (1966) was used to make computer-generated plots of the superconducting upper critical field values versus the superconducting transition temperature values for various values of the Maki paramagnetic pair-breaking parameter and the spin-orbit scattering parameter. The interpretation of the graph suggests that the experimental data for at least one sample are above the maximum WHH theoretical limit in the lower temperature range. Possible explanations of this situation are discussed. In other calculations, a scaling law was found suitable for determining pinning force densities; this data was used to calculate critical current values. The relation between resistivity and temperature was studied.
Samples were prepared by melting the metals, followed by annealing to various temperatures. The result was a structurally weak material. Sputtered films on sapphire substrates were prepared and studied. The substrates give the films mechanical strength and permit easy attachment of electrical leads. Materials were characterized by X-ray diffraction, electron microscopy, electrical resistance vs. temperature, and critical current measurements. Some of the results on CuMo6S8 are presented.