A. F. Mayadas

ELECTRICAL CHARACTERISTICS OF rf-SPUTTERED SINGLE-CRYSTAL NIOBIUM FILMS.

It is shown from measurements of the resistivity ratio (RR ≡ resistivity at room temperature divided by resistivity at 10°K), superconducting transition temperature, and transition‐temperature width that high‐quality single‐crystal niobium films can be fabricated by rf sputtering. The observed dependence of RR on sample thickness indicates that the intrinsic electron mean free path increases with thickness. Superconducting characteristics are essentially thickness independent for films thicker than approximately 1000 A.

Resistivity of Permalloy thin films

Data on resistivity at room temperature in polycrystalline and single‐crystal Permalloy (80 Ni‐20 Fe) thin films are analyzed in terms of grain boundary scattering and the dc size effect, respectively.

Long term stability of magnetoresistive bubble detectors

Various failure modes of Permalloy magnetoresistors are evaluated. Magnetic failure of magnetoresistors can be eliminated by passivation with evaporated SiO and sputtered Al 2 O 3 and Si 3 N 4 films. Effect of the permalloy/Au interaction at the sensor/lead metallization interface was investigated by high current and temperature stressing (5.5 × 106A/cm2and 330°C) of actual sensors, and by He-ion nuclear backscattering and x-ray diffraction analysis of Au/permalloy sheet film couples. Stripe cracking failures occur at the negative terminal. Significant interdiffusion of Au/permalloy can occur. However, the interdiffusion is not particularly deleterious to sensor performance.

Theory of the resistivity of inhomogeneous conducting ``fine lines''

The mechanisms contributing to the resistivity of the Al–Cu thin‐film conducting stripes used as connections on chip microcircuitry are analyzed. The excess resistivity due to the presence of copper in the stripe, both in solution and as a precipitated compound, is studied here by a general theory of mixtures and by computer simulations. Consequences of the finite size of a strip are predicted, leading to systematic increases in resistivity and variations of the resistance within populations of similarly prepared stripes. We obtain some quantitative estimates of the conditions under which such size effects became significant, and analyze the role of different preparation techniques on these size effects.

Surface Impedance of Thin Metal Films under Anomalous Skin Effect Conditions

Exact numerical solutions for the surface impedance and electric field of metal films under anomalous skin effect conditions are presented and discussed. It is shown that under certain conditions the film impedance is significantly lower than the bulk impedance.

Magnetization in Ni and Ni-Fe thin films

Nickel films have been deposited in conventional high vacuum, ultra-high vacuum, and in controlled contaminant, ultra-high vacuum environments. High field saturation magnetization M s measurements on the films made in high vacuum and an oxygen-contaminated ultra-high vacuum system show that they posses low values of M s for film thicknesses of 1000 A. The normal moments observed for ultra-high vacuum deposited films lead to the conclusion that the low M s values are associated with the oxygen and are caused by a true loss of effective magnetization rather than coupled superparamagnetism or a ripple blocking field. Supplementary torque and ferromagnetic resonance studies on the Ni and two different Ni-Fe compositions also show that the grain boundary perpendicular anisotropy models are not particularly relevant for films made under such nominal technical vacuum conditions.