de la Cruz, F. "Structural relaxation: low temperature properties.", 269. Proceedings of the Latin American Symposium of Physics of Amorphous Systems – v1. Brazil, 1984.
Abstract: We discuss the changes in transport and superconducting properties of amorphous Zr70Cu30,
induced by thermal relaxation The experimental results are used to investigate the
relation between the microscopic parameters and the observed physical properties It
is shown that the density of eletronic states determines the shift Tc as well as the
variation of the electrical resistivity It is necessary to assume strong hybridization
between s and d bands to understand the eletrodynamic response of the superconductor
(Author)
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Esparza, D. A., C. A. D'Ovidio, J. Guimpel, E. Osquiguil, L. Civale, and F. de la Cruz. "The granular nature of bulk superconductivity at 40K in La1.8Sr0.2CuO4." Solid State Communications 63, no. 2 (1987): 137–140.
Abstract: We have measured the electrical resistivity, magnetic flux expulsion and critical fields of the new high temperature superconductor La1.8Sr0.2CuO4 after different heat treatments. Our data show that the complete flux expulsion in these samples is consistent with the presence of shielding currents induced in multiple connected structures. The magnetization measurements indicate that the lowest field where flux penetrates into the sample should not be taken to be the bulk Hcl. It is shown that the absolute value of the electrical resistivity and its temperature dependence are not correlated with the superconducting critical field and temperature. We discuss the behaviour of the superconducting parameters and their relation with the electrical resistivity.
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Fernandes, A., I. Chan, J. Guimpel, O. Nakamura, D. Lederman, and I. Schuller. "Scaling of critical currents in high-temperature superconducting superlattices and thin films." Applied Physics Letters 61, no. 26 (1992): 3181.
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Franco, D. G., R. E. Carbonio, and G. Nieva. "Change in the Magnetic Domain Alignment Process at the Onset of a Frustrated Magnetic State in Ferrimagnetic La2Ni(Ni1/3Sb2/3)O6 Double Perovskite." IEEE Transactions on Magnetics 49, no. 8 (2013): 4656–4659.
Abstract: We have performed a combined study of magnetization hysteresis loops and time dependence of the magnetization in a broad temperature range for the ferrimagnetic La2Ni(Ni1/3Sb2/3)O6 double perovskite. This material has a ferrimagnetic order transition at ~100 K and at lower temperatures (~20 K) shows the signature of a frustrated state due to the presence of two competing magnetic exchange interactions. The temperature dependence of the coercive field shows an important upturn below the point where the frustrated state sets in. The use of hysteresis data, magnetization versus applied magnetic field, together with the magnetization versus time data provides a unique opportunity to distinguish between different scenarios for the low temperature regime. From our analysis, a strong domain wall pinning results in the best scenario for the low temperature regime. For temperatures larger than 20 K, the adequate scenario seems to correspond to a weak domain wall pinning.
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Lee, S. - C., M. Sullivan, G. R. Ruchti, S. M. Anlage, B. S. Palmer, B. Maiorov, and E. Osquiguil. "Doping-dependent nonlinear Meissner effect and spontaneous currents in high-Tc superconductors." Physical Review B – Condensed Matter and Materials Physics 71, no. 1 (2005).
Abstract: We measure the local harmonic generation from superconducting thin films at microwave frequencies to investigate the intrinsic nonlinear Meissner effect near Tc in the zero magnetic field. Both second and third harmonic generation are measured to identify time-reversal symmetry breaking (TRSB) and time-reversal symmetric (TRS) nonlinearities. We perform a systematic doping-dependent study of the nonlinear response and find that the TRS characteristic nonlinearity current density scale follows the doping dependence of the depairing critical current density. We also extract a spontaneous TRSB characteristic current density scale that onsets at Tc, grows with decreasing temperature, and systematically decreases in magnitude (at fixed T/TC) with underdoping. The origin of this current scale could be Josephson circulating currents or the spontaneous magnetization associated with a TRSB order parameter.
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Sereni, J. G., G. Schmerber, and J. P. Kappler. "Thermodynamic Behavior of Ce Compounds Close to a T->0 Critical Point." IEEE Transactions on Magnetics 49, no. 8 (2013): 4647–4651.
Abstract: There is a reduced group of Ce very heavy Fermions (VHF) which do not order magnetically down to at least T ≈ 500 mK because they are very close to a Tord = 0 critical point. These compounds are at the top of the limT→ 0 Cm/T specific heat values because they collect very high density of low energy excitations. From the analysis of Cm(T)/T and entropy Sm(T) dependencies performed on selected CePd3Mx ternaries (where M = B and Be) a quantitative evaluation of an upper limit for the density of excitations can be proposed. These observations exclude any evidence of Cm(T)/T divergency as T→ 0 in agreement with thermodynamic laws. A comparison with selected Yb-base VHF supports these features.
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