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The thermal and intrinsic stresses in single-crystal nickel films, in the thickness range 500-3000 AA, prepared by epitaxial growth onto the (100) cleaved surfaces of NaF, LiF, NaCl and MgO have been obtained. Calculated results from ferromagnetic resonance experiments show that the magnitudes and directions of the film stresses depend on the nature of the substrate conditions and on the sequential ordering of the deposited layers. The experimental results revealed that the thermal stresses, which are elastic and isotropic in character, are larger than the intrinsic stresses and can be of either compressive or tensile type. This type of stress disappears after the film is removed from the substrate. The present results also show that there is no single model which sufficiently accounts for the magnitudes of the intrinsic stresses in the strained films.

Thin films of Y1Ba2Cu3O7−x have been produced on MgO substrates by a chemical sol gel method. X-ray diffraction data indicate that the annealed films have the characteristic orthorhombic structure with lattice constants which are nearly the same as the values reported for the bulk specimen of Y1Ba2Cu3O7−x. Auger electron spectroscopy depth profiling measurements indicate that the films are uniform in thickness and composition. Measurements of electrical resistance of films 1–4.7 μm in thickness have been carried out between 12 and 300 K using a standard four-probe geometry. The films are superconducting with an onset temperature around 95 K and a full transition temperature as high as 79.5 K, and a critical current density of 2700 A/cm2 at 20 K. A theoretical analysis of the critical current density in Y1Ba2Cu3O7−x as a function of temperature has been made in order to determine the characteristics of the junctions between the superconducting grains. Theoretical models which describe the dependence of the critical current density on temperature have been presented and agreement has been found between these models and experimental values for sol gel films. The critical transport current has a temperature dependence which is characteristic of superconductor-normal metal-superconductor (S-N-S) type junctions. The magnitude of the resistance and thickness of the junctions has been determined from the theoretical models. Information regarding calculation of the oxygen content in Y1Ba2Cu3O7−x films is also presented.

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