Arce, R., F. de la Cruz, and P. Esquinazi. "Superconducting penetration depth in amorphous metals." Solid State Communications 38, no. 12 (1981): 1253–1255.
Abstract: We show that temperature dependent penetration depth measurements can be used to characterize the superconductive behaviour of amorphous metals.
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Arce, R., F. de la Cruz, and P. Esquinazi. "Superconducting penetration depth in amorphous La70Cu30." Physica B+C 108B (1981): 1253–1254.
Abstract: It is shown that weak field penetration depth measurements can be used to determine the change in the normal and superconducting behaviour of amorphous samples, when heat-treated below the crystallization temperature. The results are used to discuss the validity of BCS-Gorkov relations, when applied to these materials.
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Esquinazi, P., M. E. de la Cruz, A. Ridner, and F. de la Cruz. "Heat treatment effects in amorphous metals: Zr70Cu30 and La70Cu30." Solid State Communications 44, no. 6 (1982): 941–944.
Abstract: We measured the electrical resistivity (4–300 K), superconducting critical temperature and thermal conductivity (0.5–7 K) of the amorphous metals Zr70Cu30 and La70Cu30. Heat treatments below crystallization temperature induced changes in these properties. In particular, in the first stage of the annealing of Zr70Cu30 there are systematic changes in the thermal conductivity and the critical temperature, while the electrical resistivity remains constant. We show that there is no simple correlation between the thermal conductivity processes in the low temperature and plateau regions. We also show that the thermal conductivity of as quenched La70Cu30 is typical of amorphous metals, contrary to information previously reported.
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Arce, R., F. de la Cruz, and H. J. Fink. "Model relating superconductive penetration depth and metallurgical phase separation in amorphous La70Cu30." Solid State Communications 42, no. 8 (1982): 575–577.
Abstract: A model is proposed to account for the large increase in the measured penetration depth of superconducting, amorphous La70Cu30 when the specimens are annealed sufficiently long near, but below, the crystallization temperature. It is suggested that a metallurgical phase separation occurs with domain dimensions in the submicrometer range. Penetration depth measurements as a function of temperature in a weak magnetic field are a useful tool to detect changes in phase separation in high-K materials.
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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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Arce, R., F. de la Cruz, and J. Guimpel. "Superconducting behavior of amorphous Zr70Cu30." Solid State Communications 47, no. 11 (1983): 885–887.
Abstract: Measurement of the Meissner penetration depth, λ(T) were made in amorphous Zr70Cu30 samples. The results indicate that this amorphous alloy behaves as a BCS superconductor with 2Δ(0)+45 degree rulekTc = 3.8, where Δ(0) is the superconducting energy gap at T=0 and Tc the critical temperature. It is also concluded that the low energy excitation, TLS, characteristics of amorphous material does not contribute to Tc.
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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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Esquinazi, P., and F. de la Cruz. "Phonon thermal conductivity limited by electron scattering in amorphous Zr70Cu30." Physical Review B 27, no. 5 (1983): 3069–3072.
Abstract: The low-temperature thermal conductivity of amorphous Zr70Cu30 is investigated. The lattice thermal conductivity as limited by electrons in the superconducting state has been obtained at temperatures close to Tc. This has allowed for the first time the verification of the temperature dependence of the phonon conductivity as predicted by Bardeen, Rickayzen, and Tewordt. The analysis of the data in the normal and superconducting state shows that Matthiessen's rule can be used in amorphous metals to separate the different scattering processes.
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de la Cruz, F., M. E. de la Cruz, L. Civale, and R. Arce. "Hybridization effects between d and s bans in amorphous materials." In Proceedings of LT-17, 1301. Elsevier Science Publishers BV, 1984.
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