Grigera, S. A., E. Morre, E. Osquiguil, G. Nieva, and F. de la Cruz. "Two-step liquid-solid vortex transition with the field along the ab planes in YBa2Cu3O7-delta crystals." PHYSICAL REVIEW B 59, no. 17 (1999): 11201–11204.
Abstract: Resistivity measurements for different Lorentz force configurations and the detection of the longitudinal vortex velocity correlation length, with the magnetic field applied parallel to the ab planes, in the mixed state of clean and twinned YBa2Cu3O7-delta single crystals,' support the existence of a vortex-smectic phase when the vortices interact with an attractive periodic potential. The transition from the vortex-liquid to the vortex-solid state is shown to be achieved in two steps, a continuous transition from a liquid to a possible smectic phase and another continuous one from the smectic phase to a solid. [S0163-1829(99)09413-8].
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Luzuriaga, J., C. D'Ovidio, and F. de la Cruz. "Ideal two dimensional flux pinning induced by annealing in superconducting amorphous Zr75Rh25." Solid State Communications 57, no. 9 (1986): 753–756.
Abstract: By annealing amorphous Zr75Rh25 prepared by melt spinning an ideal behaviour of the critical current was observed, in which the measured pinning forces are seen to follow the two dimensional Larkin-Orchivnikov theory. In the region where this theory is valid the changes in the pinning forces can be explained by the changes in the superconducting matrix and it can be assumed that the pinning centers do not change with the heat treatment.
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Osquiguil, E., V. L. P. Frank, and F. de la Cruz. "Two dimensional collective flux pinning in melt spun superconducting amorphous Zr70Cu30." Solid State Communications 55, no. 3 (1985): 227–230.
Abstract: We have measured the critical currents in melt spun amorphous Zr70Cu30 and their evolution with heat treatment. We found that the pinning forces may be interpreted in terms of the Larkin-Ovchinnikov two dimensional collective pinning theory.
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de la Cruz, F., M. D. Maloney, and M. Cardona. "Supercooling and superheating in Al and Zn." Physica 55 (1971): 749–759.
Abstract: We have studied the supercooling and superheating of Al and Zn in the temperature range between 0.5 and 1.2 K. The samples, collections of dispersed and isolated small spheres, were prepared by spraying of the molten metal into liquid nitrogen. The supercooling and superheating fields obtained are, by all indications, close to the theoretical limit. From the supercooling fields observed we determined the Ginzburg-Landau parameter κ(Tc) = 0.015, for both Al and Zn. The superheating field exhibits a strong temperature dependence near Tc, which reflects the extremely non-local electrodynamics of the materials. The results are discussed in the light of recent theoretical work.
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Lopez, D., E. F. Righi, G. Nieva, F. de la Cruz, W. K. Kwok, J. A. Fendrich, G. W. Crabtree, and L. Paulius. "Amplification of the c-axis vortex correlation by twin-boundary pinning at the vortex liquid-solid phase transition." PHYSICAL REVIEW B 53 (1996): R8895.
Abstract: Transport measurements using the dc flux transformer configuration together with c-axis resistance data in clean and twinned YBa2Cu3O7-δ single crystals show that vortices are localized by the twin-boundary potential. The results support the existence of a divergent tilt modulus [D. R. Nelson and V. M. Vinokur, Phys. Rev. B 48, 13 060 (1993)] in a liquid that freezes into a Bose glass
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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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López, D., G. Nieva, and F. de la Cruz. "In- and out-of-plane vortex correlations in YBa2Cu3O7." Physical Review B 50 (1994): 7219.
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López, D., G. Nieva, F. de la Cruz, Henrik Jeldtoft Jensen, and Dominic O’Kane. "Flux cutting in YBa2Cu3O7-δ single crystals: Experiment and phenomenological model." Physical Review B 50 (1994): 9684.
Abstract: We measured the current-induced loss of vortex correlation in YBa2Cu3O7-δ crystals using the pseudo-dc-flux-transformer geometry. We find that the current density Jcut at which the top and bottom voltage drops differ is a linear function of temperature, is independent of pinning, and depends on the thickness of the sample. This thickness dependence strongly suggests that the electrical current flows at the surface of the sample. The observed behavior with temperature, magnetic field, and thickness is described by a phenomenological model.
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Arce, R., L. Civale, J. Luzuriaga, J. Guimpel, and F. de la Cruz. "Surface normal regions in superconducting Zr70Cu30 induced by thermal relaxation." Solid State Communications 48, no. 12 (1983): 1027–1030.
Abstract: Penetration depth measurements show that thermal heat treatment in amorphous Zr70Cu30 induces a normal region 5000 Å thick at the surface of ultrarapid quenched ribbons. Upper critical field measurements indicate that the new induced phase is a normal one while the rest of the sample remains as a homogeneous superconducting phase.
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Civale, L., F. de la Cruz, and J. Luzuriaga. "Critical temperature and density of states in amorphous Zr70Cu30." Solid State Communications 48, no. 4 (1983): 389–391.
Abstract: By means of thermal heat treatment of amorphous Zr70Cu30 it is shown that the induced decrease in critical temperature is followed by a reduction in the electronic density of states of the same magnitude as that obtained by changing the Cu concentration. This result indicates that the density of states is the fundamental microscopic parameter determining the superconducting behavior.
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