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A study has been made of the magnetic-coupling properties of vortex arrays in a dc superconducting transformer compost' of two oxygen-doped aluminum films separated by a thin insulating layer. By doping to the appropriate level, very small depixming cu-awaits have been achieved, making possible an investigation of the vortex~upling characteristics in a low-current regime free of heating instabilities. Measurements of the system's V-I characteristics have been obtained at currents more than an order of magnitude greater than the current at which the two vortex lattices cease to move at the same velocity. A simple periodic-coupling-force model has been used to generate theoretical V-I curves which are found to compare well with the experimental data Values of the magnetic interaction force coupling the two vortex arrays have been determined as a function of temperature and intervortex spacing, and are compared with theory.

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The specific heats of solid neon and xenon have been measured in the temperature range 1.5 to 24°K, using a calorimeter with a mechanical heat switch. Carbon resistance thermometers were calibrated against a gas thermometer and the helium vapor-pressure scale. The results were analyzed to obtain the temperature dependence of the Debye temperature, в с (Г). In the range 0.020<Г/в 0 с <0.505, the data were fitted with an expression of the form В с (Т)=во с +АТ 2 ,where G 0 C is the Debye temperature at 0°K. This procedure gave 0 o c =74.6dbl.O°K for neon and е 0 с = 64.0±0.8°К for xenon. The results for в с (Т) are compared with the calculations of Bernardes, Horton, and Leech, and Barron and Klein, based on Mie-Lennard-Jones potentials for the interaction energy between two atoms. Tables of the following smoothed thermodynamic properties between 1.0 and 24°K are given in Table I: specific heat at constant pressure, specific heat at constant volume, entropy, and enthalpy.