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Author (up) Esquinazi, P.; Guillet, B.; Steinmann, R.; Dussel, H.
Title Flux pinning in a La70Cu30 disordered system Type Journal Article
Year 1985 Publication Journal of Non-Crystalline Solids Abbreviated Journal
Volume 69 Issue 2-3 Pages 171-187
Keywords
Abstract Superconducting critical currents were measured as a function of a perpendicular applied magnetic field in disordered La70Cu30.

It is shown that the pinning force is very sensitive to inhomogeneities already present in the as-quenched samples, although these inhomogeneities have no obvious influence on other superconducting and transport properties. A simple series resistance model is used to explain the magnetic field dependence of the pinning force. A large decrease of the pinning force was obtained for the annealed samples. This behaviour is consistent with the phase separation model that explains the evolution of the superconductive penetration depth. In order to obtain a better characterization of the structural evolution with annealing of the La70Cu30 system, the behaviour of the electrical resistivity, superconducting critical temperature and differential thermal analysis were measured.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3093 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 568
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Author (up) 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 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 (up) 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 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
Series Volume Series Issue Edition
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 (up) Esquinazi, P.; Luzuriaga, J.; Durán, C.; Esparza, D.A.; D'Ovidio, C.
Title Anomalies in the internal friction and sound velocity in the high-temperature superconductor La1.8Sr0.2CuO4 Type Journal Article
Year 1987 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 36 Issue 4 Pages 2316-2318
Keywords
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.
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): 6; Export Date: 28 April 2009; Source: Scopus; doi: 10.1103/PhysRevB.36.2316; Language of Original Document: English; Correspondence Address: Esquinazi, P.; Centro Atomico Bariloche; Instituto Balseiro 8400 Bariloche, Argentina Approved no
Call Number BT @ luzuriag @ Serial 498
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Author (up) Favaron, J.; de la Cruz, M.E.; Esquinazi, P.; de la Cruz, F.
Title Phase diagram and superconductive properties of splat-cooled CuxLa1-x Type Journal Article
Year 1980 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 21 Issue 7 Pages 2804-2808
Keywords
Abstract The phase diagram of nonequilibrium, splat-cooled CuxLa1-x is interpreted by means of superconductive-transition and x-ray measurements. At the eutectic composition the material is shown to be in a highly disordered state. Measurements of dc resistance and ac susceptibility show that there are two different critical fields at the disordered concentration although there is a unique critical temperature.
Address
Corporate Author Thesis
Publisher American Physical Society Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ PhysRevB.21.2804 Serial 535
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Author (up) Izbizky, M.A.; Núñez Regueiro, M.; Esquinazi, P.; Durán, C.; Fainstein, C.
Title Phonon transport in superconducting EuBa2Cu3O7-x Type Journal Article
Year 1988 Publication Physics Letters A Abbreviated Journal Phys. Lett. A
Volume 129 Issue 1 Pages 71-75
Keywords
Abstract We have measured the thermal conductivity, Young modulus sound velocity and internal friction of a polycrystalline sample of the ceramic superconductor EuBa2Cu3O7-x. The low temperature data can be quantitavely understood assuming the interaction of phonons with tunneling systems.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0375-9601 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 571
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Author (up) Izbizky, M.A.; Núñez Regueiro, M.; Esquinazi, P.; Fainstein, C.
Title Thermal conductivity and superconductivity in EuBa2Cu3O7-x Type Journal Article
Year 1988 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 38 Issue 13 Pages 9220-9223
Keywords
Abstract
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Corporate Author Thesis
Publisher American Physical Society Place of Publication Editor
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Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ 10.1103/PhysRevB.38.9220 Serial 573
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Author (up) Martinez, E.N.; Esquinazi, P.; Luzuriaga, J.
Title Measurements of the superfluid transition in helium by means of a vibrating reed Type Journal Article
Year 1990 Publication American Journal of Physics Abbreviated Journal Am. J. Phys.
Volume 58 Issue 12 Pages 1163-1168
Keywords
Abstract A relatively simple method is presented that has been used in an undergraduate experimental course for observing the superfluid transition in 4He. The experimental technique consists of submerging a vibrating reed in liquid helium and observing the changes in frequency and damping (energy dissipation) as the temperature is regulated above and below the superfluid transition. The results of the measurements are interpreted by means of a simplification of the acting hydrodynamic forces, and it is seen that most of the relevant physics is well described by the approximations.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0002-9505 ISBN Medium
Area Expedition Conference
Notes ISI:A1990EJ58300010 Approved no
Call Number BT @ hernan @ Serial 258
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Author (up) Núñez Regueiro, M.; Esquinazi, P.; Izbizky, M.A.; Durán, C.; Castello, D.; Luzuriaga, J.
Title Tunneling systems in high temperature superconductors Type Journal Article
Year 1988 Publication Annales de Physique Abbreviated Journal Ann. Phys. Fr.
Volume 13 Issue 5 Pages 401-406
Keywords acoustic wave absorption; acoustic wave velocity; barium compounds; high temperature superconductors; lanthanum compounds; rare earth compounds; strontium compounds; superconductive tunnelling; thermal conductivity of solids; tunnelling systems; high temperature superconductors; thermal conductivity; sound attenuation; sound velocity; model; low temperature specific heat; La Sr Cu O
Abstract We have measured the thermal conductivity, sound attenuation and relative variation of sound velocity of compounds of the La-Sr-Cu-O and RBa2Cu3O7 families, where R is a rare-earth. We have found that all these properties can be quantitatively correlated within a tunneling system model similar to that used in amorphous materials. This interpretation would naturally explain the anomalous linear term of the low temperature specific heat observed in these materials.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-4169 ISBN Medium
Area Expedition Conference
Notes ISI:A1988Q715000009 Approved no
Call Number BT @ hernan @ Serial 264
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Author (up) Núñez Regueiro, M.; Esquinazi, P.; Izbizky, M.A.; Duran, C.; Castello, D.; Luzuriaga, J.; Nieva, G.
Title Evidence of tunneling systems through thermal and acoustic measurements in ceramic materials Type Journal Article
Year 1988 Publication Physica C: Superconductivity and its applications Abbreviated Journal Physica C
Volume 153-155 Issue PART 2 Pages 1016-1017
Keywords Acoustic Variables Measurement--Wave Velocity; Ceramic Materials--Thermal Conductivity; Europium Barium Copper Oxides; Superconducting Materials
Abstract We have neasured the sound velocity, internal friction, thermal conductivity and specific heat of La-based and (Y/Eu)- based ceramics. The low temperature data can be understood in terms of the Tunneling Model assuming the existence of Tunneling Systems (TS). From these measured properties we obtain values for the parameter C=P?2/?v2, where P is the density of states of TS, ? the coupling constant between phonons and TS, ? the mass density and v the sound velocity close to those obtained for amorphous and “orientational” disordered crystalline materials. Our data would indicate that the TS are intrinsic defects independent of the sample porosity.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 09214534 (ISSN) ISBN Medium
Area Expedition Conference International Conference on High Temperature Superconductors and Materials and Mechanisms of Superconductivity
Notes Export Date: 28 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Regueiro, M.N.; Centro At Approved no
Call Number BT @ luzuriag @ Serial 496
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