|
|
Esquinazi, P., J. Luzuriaga, and C. Durán. "Vibrating-reed studies of flux pinning in the superconducting metallic glass Zr70Cu30." Physical Review B 37, no. 7 (1988): 3689–3692.
Abstract: With the vibrating-reed technique we have measured the resonance frequency and damping of superconducting ribbons of a Zr70Cu30 amorphous alloy as a function of magnetic field and temperature for different heat treatments of the same sample. Through these measurements we obtain the Labusch parameter in the reduced-field (b) range 5
|
|
|
|
Luzuriaga, J. "Pinning forces and defects as measured by critical currents in amorphous superconducting materials." Physical Review B 35, no. 7 (1987): 3625–3628.
Abstract: Analysis of the available data on critical currents in amorphous superconductors shows a striking similarity in the defects responsible for the pinning force in all samples in which two-dimensional flux pinning can be observed. Order-of-magnitude calculations show that this is consistent with the existence of disclinations in glasses as has been proposed in different theoretical papers by Rivier, Nelson, Kleman, and Sadoc. The evolution of pinning forces with annealing also shows a similar behavior in all the published data, and the trend is towards a state with fewer or smaller disclinations. If disclinations are identified with two-level systems this trend is consistent with a decrease of the scattering of phonons by TLS which is observed upon annealing in thermal conductivity measurements.
|
|
|
|
Luzuriaga, J., M. - O. Andre, and W. Benoit. "Mechanical response of the flux lines in ceramic YBa2Cu3O7-." Physical Review B 45, no. 21 (1992): 12492–12497.
Abstract: We have studied the mechanical response of the flux-line lattice (FLL) in ceramic samples of YBa2Cu3O7 by means of a low-frequency forced pendulum. The internal friction and elastic modulus variation of the FLL have been measured as a function of temperature for different values of the applied stress. A somewhat different behavior was observed whether a zero-field-cooling or field-cooling procedure was followed. Measurements of the internal friction and elastic modulus as a function of the applied stress at constant temperature show amplitude-dependent dissipation, with a maximum dissipation at intermediate values of the stress. This dependence is well fitted by a rheological model of extended dry friction, if we restrict ourselves to the dissipation and modulus at fixed temperature. The agreement is not so good when attempting to extend the model to fit the temperature dependence.
|
|
|
|
Giordano, J. L., J. Luzuriaga, Ruíz-Tagle, G. NIEVA, and Badía-Majós. "Magnetization measurements of hard superconductors under dissipative transport." Journal of Physics: Conference Series 43, no. 1 (2006): 663–666.
Abstract: The hysteretic magnetic flux dynamics of ceramic type-II superconductors under superimposed transport current cycles has been investigated. Field cooled and zero field cooled experiments were carried-out on polycrystalline YBa 2Cu3O7-x cylinders by using both temperature and applied field control, to drive the sample into the semi-reversible granular regime. The transport current magnitude was near and above the dissipative threshold. The interplay between shielding and transport due to vortex-pinning interactions, equilibrium magnetization effects, and diamagnetic/paramagnetic relaxation phenomena are shown to play an important role in the range of practical applications.
|
|
|
|
Rodriguez, E., J. Luzuriaga, C. A. Dovidio, and D. A. Esparza. "Softening of the flux-line structure in La1.8Sr0.2CuO4 measured by a vibrating reed." Physical Review B 42, no. 16 (1990): 10796–10799.
Abstract: Vibrating-reed measurements in La1.8Sr0.2CuO4 in a magnetic field show that the flux-line structure (FLS) becomes uncoupled from the material at a temperature TH of 23 K, much below the critical temperature of the sample, which is 32 K. The behavior is similar to that found in Bi2Sr2CaCu2O8 but shows some significant differences, the most important being that TH changes little with magnetic field throughout the measured field range (0.01 TH1 T). For low fields, TH is below the reversibility line of the magnetization. This seems to imply that the reversibility line and the line at which the FLS softens have to be considered as distinct physical phenomena. It is argued that neither flux-lattice melting nor giant flux creep considered separately can account for the data in a wholly satisfactory manner.
|
|
|
|
De La Cruz, F., J. Luzuriaga, E. N. Martinez, and E. J. Osquiguil. "Current-voltage characteristics in collective pinning." Physical Review B 36, no. 13 (1987): 6850–6852.
Abstract: The critical-current curves of amorphous samples which exhibit collective flux pinning have been analyzed, and it was found that the nonlinear part can be fitted by an expression of the form V(I)[(I-IK)/IK]. This form, which could be due to critical behavior, is consistent with an interpretation of the unpinning of vortices in the collective regime as a phase transition between the static flux-line lattice (FLL) and the FLL in steady-state movement as has been proposed by Fisher.
|
|
|
|
Luzuriaga, J. "Upper critical field in superconductors and the uncertainty principle: Upper limit to the maximum slope of Hc2." Physical Review B 42, no. 1 (1990): 934–935.
Abstract: Consideration of the formulas that give the upper critical field Hc2 near the critical temperature Tc for superconductors in the dirty limit, together with the uncertainty principle, is shown to provide an upper limit to the maximum slope of Hc2. Analysis of reported values shows that amorphous superconductors are in this limit.
|
|
|
|
Luzuriaga, J. "Even in translation, Richter's 'science' unimpressive." Physics Today 58, no. 1 (2005): 14–15.
|
|
|
|
Ceva, H., and J. Luzuriaga. "Correlations in the sand pile model: From the log-normal distribution to self-organized criticality." Physics Letters A 250, no. 4-6 (1998): 275–280.
Abstract: We have studied the approach of the Abelian sand pile model towards the stationary, self-organized criticality state. The uncorrelated limit is shown both numerically and by a simple analysis to follow the log-normal distribution. We introduce and evaluate several correlation functions to study the correlated region.
|
|
|
|
Esquinazi, P., J. Luzuriaga, C. Durán, D. A. Esparza, and C. D'Ovidio. "Anomalies in the internal friction and sound velocity in the high-temperature superconductor La1.8Sr0.2CuO4." Physical Review B 36, no. 4 (1987): 2316–2318.
Abstract: The internal friction Q-1 and the Young's-modulus sound velocity vE have been measured in La1.8Sr0.2CuO4 using the vibrating-reed technique. Measurements were performed at a frequency of 700 Hz at temperatures between 0.2 and 100 K. A drastic change of slope in the internal friction versus temperature curve is observed at T=44 K just above the superconducting transition temperature Tc=40 K. A plateau in Q-1 is observed between 44 and 5 K. The sound velocity shows a decrease with decreasing temperature between 100 and 20 K and remains almost constant between 2 and 0.2 K.
|
|
