Cotignola, J. M., F. de la Cruz, M. E. de la Cruz, and R. P. Platzeck. "Thermal Conductivity of Polycrystalline Zinc below 1 K." Review of Scientific Instruments 38, no. 1 (1967): 87–92.
Abstract: Measurements of the thermal conductivity of samples of polycrystalline zinc of thickness 0.1 mm have been carried out between 0.12 and 0.9°K in the normal as well as in the superconducting state to investigate the usefulness of zinc as a thermal switch. The conductivity in the normal state shows a linear dependence on temperature. In the superconducting state it shows a behavior typical of electronic conductivity down to the lowest temperature measured. By applying a magnetic field between 40 and 5000 Oe, magnetoresistivity was also investigated and a strong dependence of thermal conductivity on field was found. Electrical resistivity measurements were performed in magnetic fields at liquid 4He temperatures. The resistivity was found to be independent of temperature for fields up to 9000 Oe. The effect of solder joints using Cd, Sn, In, Zn, and Wood's metal was also investigated, Cd giving the least resistance. The measurements show that zinc should be a useful thermal switch for temperatures below 0.1 and 0.2°K, though effect of a magnetic field on the normal conductivity must be carefully considered.
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Tutzauer, H., P. Esquinazi, M. E. de la Cruz, and F. de la Cruz. "Production of ribbon quenched samples using an arc furnace." Review of Scientific Instruments 51, no. 6 (1980): 855–856.
Abstract: We describe a new device to produce ribbons of disordered metals by ultrarapid quenching combining an arc furnace with a rotating cylinder. The characterization of samples of disordered La70 Cu30 and La76Au24 prepared using this method shows good agreement with those obtained by other authors for the same alloys.
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Favaron, J., M. E. de la Cruz, P. Esquinazi, and F. de la Cruz. "Phase diagram and superconductive properties of splat-cooled CuxLa1-x." Physical Review B 21, no. 7 (1980): 2804–2808.
Abstract: The phase diagram of nonequilibrium, splat-cooled CuxLa1-x is interpreted by means of superconductive-transition and x-ray measurements. At the eutectic composition the material is shown to be in a highly disordered state. Measurements of dc resistance and ac susceptibility show that there are two different critical fields at the disordered concentration although there is a unique critical temperature.
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de la Cruz, F., M. E. de la Cruz, and J. M. Cotignola. "Longitudinal Magnetomorphic Effect in Indium Films." Physical Review 163, no. 3 (1967): 575–578.
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Guimpel, J., F. de la Cruz, J. Murduck, and I. K. Schuller. "Penetration depth of a superconducting superlattice." Physical Review B 35, no. 7 (1987): 3655–3656.
Abstract: We have measured the magnetic-flux expulsion of a superconducting superlattice and related it to the Meissner penetration depth. The temperature dependence of the penetration depth is in quantitative agreement with theoretical expectation based on mean-field theory. The zero-temperature penetration depth is found in excellent, quantitative agreement without adjustable parameters with theoretical predictions for dirty superconductors.
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Guimpel, J., L. Civale, F. de la Cruz, J. M. Murduck, and I. K. Schuller. "Dimensional phase transition in superconductors with short coherence length." Physical Review B 38, no. 4 (1988): 2342–2344.
Abstract: We found a novel dimensional transition in the vortex lattice of a finite-sized superconductor. The low-field dependence (with field applied parallel to the film plane) of the magnetization exhibits two maxima, which signal the transition from one to two dimensions. In one dimension the vortices line up along the film, and with increasing field their arrangement changes into a two-dimensional array due to the competition between vortex-surface and vortex-vortex repulsion. Agreement is found with no adjustable parameter calculations using a priori known surface-barrier and vortex-repulsion effects.
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Guimpel, J., and F. de la Cruz. "Electrical resistivity of amorphous Zr70Cu30 and the Kondo like model." Solid State Communications 44, no. 7 (1982): 1045–1046.
Abstract: Electrical resistivity measurements of amorphous Zr70Cu30 as a function of the concentrations of two level systems show that a Kondo like theory cannot explain the observed temperature dependence.
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Duran, C., J. Yazyi, F. de la Cruz, D. J. Bishop, D. B. Mitzi, and A. Kapitulnik. "Flux-lattice melting, anisotropy, and the role of interlayer coupling in Bi-Sr-Ca-Cu-O single crystals." Physical Review B 44, no. 14 (1991): 7737–7740.
Abstract: We have used the high-Q mechanical-oscillator technique to probe the vortex-lattice structure in high-quality Bi-Sr-Ca-Cu-O single crystals over a wide range of magnetic fields (200 Oe to 40 kOe), and relative orientations θ between the magnetic field and the crystalline c^ axis. In addition to the large softening and dissipation peak previously observed and interpreted as due to flux-lattice melting, another distinctly different peak at higher temperatures is seen. The temperatures where the dissipation peaks take place are solely defined by the parallel component of the field cosθ, while the restoring force on the oscillator is due to both field components. We suggest that the two peaks are due to the softening of interplanar coupling at the low-temperature peak, and melting or depinning of the two-dimensional pancake vortices at the higher-temperature peak.
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de la Cruz, F., M. E. de la Cruz, and J. M. Cotignola. Efecto magnetomorfico longitudinal en laminas de In. Buenos Aires, 1968.
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de la Cruz, F., and O. J. Bressan. "Sensitive Hot Wire Level Detector for Cryogenic Liquids." Review of Scientific Instruments 40, no. 3 (1969): 483–486.
Abstract: A very simple and highly sensitive ``hot wire'' type level detector to be used with cryogenic liquids is described. The hot filament is made of tungsten wire of about 4 µ diam. The tests on the sensor were made moving the filament in and out of the quiescent surfaces of liquid helium and nitrogen. The results showed 0.006 mm sensitivity in the determination of liquid helium level and 0.002 mm sensitivity in the case of liquid nitrogen level. The sensor is assembled in such a way that it can be used without special precautions during indefinite periods of time. For the case when the full capabilities of the sensor are not necessary, a simple circuit is presented.
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