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Author Luzuriaga, J.
Title Pinning forces and defects as measured by critical currents in amorphous superconducting materials Type Journal Article
Year 1987 Publication Physical Review B Abbreviated Journal
Volume 35 Issue 7 Pages (up) 3625-3628
Keywords
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.
Address Centro Atomico Bariloche, Instituto Balseiro, 8400 Bariloche, Argentina
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Series Editor Series Title Abbreviated Series Title
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ISSN 01631829 (ISSN) ISBN Medium
Area Expedition Conference
Notes Export Date: 28 April 2009; Source: Scopus; doi: 10.1103/PhysRevB.35.3625; Language of Original Document: English; Correspondence Address: Luzuriaga, J.; Centro Atomico Bariloche; Instituto Balseiro 8400 Bariloche, Argentina Approved no
Call Number BT @ luzuriag @ Serial 497
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Author Esquinazi, P.; Luzuriaga, J.; Durán, C.
Title Vibrating-reed studies of flux pinning in the superconducting metallic glass Zr70Cu30 Type Journal Article
Year 1988 Publication Physical Review B Abbreviated Journal
Volume 37 Issue 7 Pages (up) 3689-3692
Keywords
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
Address Centro Atomico Bariloche, Instituto Balseiro, 8400 Bariloche, Argentina
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN 01631829 (ISSN) ISBN Medium
Area Expedition Conference
Notes Export Date: 28 April 2009; Source: Scopus; doi: 10.1103/PhysRevB.37.3689; Language of Original Document: English; Correspondence Address: Esquinazi, P.; Centro Atomico Bariloche; Instituto Balseiro 8400 Bariloche, Argentina Approved no
Call Number BT @ luzuriag @ Serial 495
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Author De La Cruz, F.; Luzuriaga, J.; Martinez, E.N.; Osquiguil, E.J.
Title Current-voltage characteristics in collective pinning Type Journal Article
Year 1987 Publication Physical Review B Abbreviated Journal
Volume 36 Issue 13 Pages (up) 6850-6852
Keywords
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.
Address Centro Atomico Bariloche, Instituto Balseiro, 8400 Bariloche, Argentina
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 01631829 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 2; Export Date: 17 April 2009; Source: Scopus; doi: 10.1103/PhysRevB.36.6850; Language of Original Document: English; Correspondence Address: De La Cruz, F.; Centro Atomico Bariloche; Instituto Balseiro 8400 Bariloche, Argentina Approved no
Call Number BT @ osquigui @ Serial 417
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Author Safar, H.; Durán, C.; Guimpel, J.; Civale, L.; Luzuriaga, J.; Rodriguez, E.; de la Cruz, F.; Fainstein, C.; Schneemeyer, L.F.; Waszczak, J.V.
Title Logarithmic-to-nonlogarithmic flux-creep transition and magnetic-flux hardening in Bi-Sr-Ca-Cu-O superconducting ceramics Type Journal Article
Year 1989 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 40 Issue 10 Pages (up) 7380
Keywords
Abstract A sharp temperature- and field-dependent transition from a logarithmic to a nonlogarithmic flux-creep behavior has been found in Bi-Sr-Ca-Cu-O superconductors. The transition is not followed by any noticeable change in the magnetization. However, vibrating-reed measurements show that it coincides with a strong hardening of the magnetic structure. The transition occurs at fields and temperatures well below the reversibility line. The possible relation to the recently proposed flux lattice melting is discussed.
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Corporate Author Thesis
Publisher American Physical Society Place of Publication Editor
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Notes Approved no
Call Number BT @ jguimpel @ 10.1103/PhysRevB.40.7380 Serial 627
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Author Esquinazi, P.; Luzuriaga, J.
Title Annealing effects on the sound velocity and internal friction in the superconducting and normal states of the Cu30Zr70 amorphous alloy Type Journal Article
Year 1988 Publication Physical Review B Abbreviated Journal
Volume 37 Issue 13 Pages (up) 7819-7831
Keywords Zr70Cu30
Abstract By means of the vibrating-reed technique we have measured the evolution upon low-temperature annealing of the internal friction Q-1 and sound velocity v of the Cu30Zr70 amorphous alloy between 0.1 and 10 K. With an applied magnetic field of 5.6 T we measured also the normal-state behavior of both properties. Upon annealing, the internal friction and the slope of the logarithmic temperature dependence of v in the superconducting state decrease, in agreement with the standard tunneling model. Our results indicate that with thermal treatments, the coupling constant between tunneling systems (TSs) and phonons decreases, and the density of states of the TS remains constant or decreases, at most 25%, in the fully relaxed state, which is in agreement with published specific-heat results in these materials. From our data we conclude that the coupling constant between the TS and phonons should be very sensitive to the relaxed state of the disordered structure. The sound-velocity behavior strongly indicates that relaxation processes up to 10 K involve the interaction with the TS. A well-defined change of slope in v at the superconducting critical temperature Tc is observed in the as-quenched and the first relaxed state, which cannot be explained with the standard tunneling model and the Korringa-like relaxation rate between the TS and electrons. Several features observed in the superconducting and normal states lead to the conclusion that the TS-electron interaction problem remains unsolved.
Address Centro Atómico Bariloche, Instituto Balseiro, 8400 Bariloche, Argentina
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 01631829 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 9; Export Date: 28 April 2009; Source: Scopus; doi: 10.1103/PhysRevB.37.7819; Language of Original Document: English; Correspondence Address: Esquinazi, P.; Centro Atmico Bariloche; Instituto Balseiro 8400 Bariloche, Argentina Approved no
Call Number BT @ luzuriag @ Serial 494
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Author Rodriguez, E.; Luzuriaga, J.; Dovidio, C.A.; Esparza, D.A.
Title Softening of the flux-line structure in La1.8Sr0.2CuO4 measured by a vibrating reed Type Journal Article
Year 1990 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 42 Issue 16 Pages (up) 10796-10799
Keywords
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.
Address Centro Atmico Bariloche, (8400) Bariloche, Argentina
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 01631829 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 2; Export Date: 28 April 2009; Source: Scopus; doi: 10.1103/PhysRevB.42.10796; Language of Original Document: English; Correspondence Address: Rodrguez, E.; Centro Atmico Bariloche (8400) Bariloche, Argentina Approved no
Call Number BT @ luzuriag @ Serial 489
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Author Herbsommer, J.A.; Nieva, G.; Luzuriaga, J.
Title Interaction of vortices with oriented twin boundaries in single-crystal YBa2Cu3O7-delta Type Journal Article
Year 2000 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 61 Issue 17 Pages (up) 11745-11751
Keywords
Abstract We have studied the response of the vortex lattice (VL) in a YBa2Cu3O7-delta sample with oriented twin boundaries (TB's) and in an untwinned sample. In the twinned sample the density of twin boundaries is estimated from decoration experiments. The TB's affect the liquid-to-solid transition in the vortex structure, which is of first order in the twin free crystal and to a Bose glass in the twinned sample. We measure the ac susceptibility, and find that the response strongly depends on the orientation of the probing ac field with respect to the TB's. The ac field produces a tilting stress on the vortices. With the applied de magnetic field H-dc parallel to the c axis, the response of the VL is weaker when the tilt is parallel to the TB's than when it is perpendicular or at 45 degrees to the TB's. The results are explained by the fact that the VL is locked to the twin boundaries for small deviations of H-dc from the c axis and is partially pinned to them for larger angles. By measuring over the whole angular range we estimate the angles over which each regime is realized for different temperatures. The results of the detwinned sample are used for comparison.
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Series Volume Series Issue Edition
ISSN 1098-0121 ISBN Medium
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Notes ISI:000086937700090 Approved no
Call Number BT @ hernan @ Serial 228
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Author Luzuriaga, J.; Badía-Majós, A.; Nieva, G.; Giordano, J.L.; Lopez, C.; Serquis, A.; Serrano, G.
Title Experimental and numerical study of transverse flux shaking in MgB2 superconductors Type Conference Article
Year 2009 Publication Journal of Physics: Conference Series Abbreviated Journal J. Phys.: Conf. Ser.
Volume 167 Issue Pages (up) 012009
Keywords
Abstract Magnetization measurements in the mixed state of thick strips of carbon nanotube

doped MgB

2

in crossed fields configurations are reported, together with numerical simulations

performed with a geometry equivalent to the sample shape. The samples were subjected to

magnetic field components along mutually perpendicular directions, an oscillatory field in one

direction and a remanent magnetization in the perpendicular direction. The magnetic response

along the oscillatory field and the magnetic relaxation perpendicular to it are observed and

simulated using the critical state theory. A remarkable quantitative agreement between the

experiment and the theory was obtained.
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Area Expedition Conference XIX Latin American Symposium on Solid State Physics (SLAFES XIX)
Notes Approved no
Call Number BT @ pedrazp @ Serial 737
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Author Zemma, E.; Luzuriaga, J.; Babuin, S.
Title Analysis of motion of solid hydrogen tracer particles in oscillating superfluid flows Type Conference Article
Year 2014 Publication Journal of Physics: Conference Series Abbreviated Journal J. Phys.: Conf. Ser.
Volume 568 Issue Pages (up) 012029
Keywords
Abstract We have developed a relatively simple cryostat which allows us to image turbulent flows in superfluid helium at temperatures below 2 K, using frozen H2 particles. We analyze the statistics of the velocities of these solid tracers, which follow the turbulent flow generated by oscillating bodies. We have also studied one of the oscillators working in air at room temperature, and traced the flow with solid talcum particles for comparison. Images were recorded by a digital camera at 240 frames per second, while frequencies of the oscillators are between 20 to 45 Hz. The flow is characterized by a modified Reynolds number Reδ based on the viscous penetration depth δ. Software in a dedicated particle tracking velocimetry code allows us to compute the trajectories and velocities of tens of thousands of particles. We have obtained the number of particles for equally spaced intervals of the velocity modulus. For the oscillators in the superfluid, the probability of finding particles at higher velocities has an exponential decay. Within our resolution the statistics in the superfluid for oscillating objects with sharp borders is largely independent of Reδ, while the logarithmic decay at low velocities seems faster than for high velocities for rounded objects. On the other hand, for data taken in air the result is closer to a classical Gaussian distribution of velocities.
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Area Expedition Conference 27th International Conference on Low Temperature Physics (LT27)
Notes Approved no
Call Number BT @ pedrazp @ Serial 735
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Author Luzuriaga, J.; Andre, M.-O.; Benoit, W.
Title Mechanical response of the flux lines in ceramic YBa2Cu3O7- Type Journal Article
Year 1992 Publication Physical Review B Abbreviated Journal
Volume 45 Issue 21 Pages (up) 12492-12497
Keywords
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.
Address Institut de Genie Atomique, Ecole Politechnique Federal de Lausanne, (1015) Ecublens, Switzerland
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ISSN 01631829 (ISSN) ISBN Medium
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Notes Export Date: 28 April 2009; Source: Scopus; doi: 10.1103/PhysRevB.45.12492; Language of Original Document: English; Correspondence Address: Luzuriaga, J.; Institut de Genie Atomique; Ecole Politechnique Federal de Lausanne (1015) Ecublens, Switzerland Approved no
Call Number BT @ luzuriag @ Serial 522
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