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Author Herbsommer, Juan A.
Title Dinámica y estática de vórtices en superconductores de alta temperatura crítica con defectos correlacionados Type Book Whole
Year 2000 Publication (up) Abbreviated Journal
Volume Issue Pages
Keywords
Abstract
Address Instituto Balseiro
Corporate Author Thesis Ph.D. thesis
Publisher Place of Publication Editor
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ hernan @ Serial 328
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Author Luzuriaga, J.
Title Sphere on a vibrating reed for measurements of turbulence in superfluid helium Type Journal Article
Year 2000 Publication (up) Journal of Alloys and Compounds Abbreviated Journal J Alloys Compd
Volume Issue Pages 265-268
Keywords Cantilever beams; Computational methods; Laminar flow; Oscillators (electronic); Phase transitions; Turbulent flow; Vibrations (mechanical); Oscillating spheres; Spherical geometries; Vibrating reeds; Superfluid helium
Abstract A modification of the vibrating reed, in which a massive sphere is made to oscillate at the end of a cantilevered beam, has been used for measurements in superfluid helium. The apparatus operates in the same way as a conventional vibrating reed with capacitive detection and drive. However, when operating submerged in the liquid, the frequency changes give information on the superfluid fraction, and the dissipation can be used to obtain information on the change of liquid flow, from laminar to turbulent. The spherical geometry allows an exact calculation of all parameters in the laminar regime, so departures due to the turbulence can be better quantified. The method has been found to work well in practice, and some measurements on the turbulent regime in the superfluid are presented.
Address Centro At
Corporate Author Thesis
Publisher Elsevier Sequoia SA Place of Publication Buenos Aires, Argent Editor
Language Summary Language Original Title
Series Editor Series Title 12th International Conference on Internal Friction and Ultrasonic Attenuation in Solids (ICIFUAS-12) Abbreviated Series Title
Series Volume 310 Series Issue 1-2 Edition
ISSN 09258388 (ISSN) ISBN Medium
Area Expedition Conference
Notes Conference code: 57483; Export Date: 28 April 2009; Source: Scopus; CODEN: JALCE; doi: 10.1016/S0925-8388(00)00962-2; Language of Original Document: English; Correspondence Address: Luzuriaga, Javier; Centro Atomico Bariloche Bariloche, Argentina; Sponsors: ABDUS SALAM International Centre for Theoretical Physics; Centre for Industrial Research (CINI); Comision Nacional de Actividades Espaciales (CONAE) Approved no
Call Number BT @ luzuriag @ Serial 478
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Author Steren, L.B.; Sirena, M.; Guimpel, J.
Title Substrate effect on the magnetic behavior of manganite films Type Journal Article
Year 2000 Publication (up) JOURNAL OF APPLIED PHYSICS Abbreviated Journal
Volume 87 Issue 9 Pages 6755-6757
Keywords
Abstract The film thickness (t) dependence of the magnetic properties of La0.6Sr0.4MnO3 (LSMO) films grown on (001) MgO and (001) SrTiO3 substrates has been studied. Hysteresis loops measured at low temperature show a smooth increase of the retentivity accompanied by a decrease of the coercitive field as the film thickness increases. The increase of coercitivity with decreasing t can be interpreted in terms of a change in the domain structure of the films mainly due to an augmentation of domain pinning defects. The magnetic anisotropy has been measured using ferromagnetic resonance (FMR). A volume (VA) and a surface (SA) anisotropy contribution have been deduced from FMR angular dependence studies for both series of samples. In the LSMO films grown on MgO a VA component that corresponds to an easy-axis perpendicular to the plane of the films has been found while in contrast, the LSMO films grown on SrTiO3 present an easy-plane anisotropy. The SA is positive for both series favoring a perpendicular magnetic anisotropy. The measured magnetic anisotropy has been assigned to substrate-induced effects. (C) 2000 American Institute of Physics. [S0021-8979(00)55708-9].
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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 0021-8979 ISBN Medium
Area Expedition Conference
Notes ISI:000086728800281 Approved no
Call Number BT @ hernan @ Serial 178
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Author Steren, L.B.; Sirena, M.; Guimpel, J.
Title Substrate influence on the magnetoresistance and magnetic order in La0.6Sr0.4MnO3 films Type Journal Article
Year 2000 Publication (up) JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 211 Issue 1-3 Pages 28-34
Keywords
Abstract We report structural, magnetic and transport measurements on La0.6Sr0.4MnO3 thin films grown on MgO and TiSrO3 substrates with thickness varying from 5 to 500 nm. We find that the lattice mismatch between substrates and films affects the morphology and induced-strains of the films. We show that these two different effects strongly influence the ferromagnetic order, the metal-insulator transition, the localization of the current carriers and the magnetoresistance of these materials. (C) 2000 Elsevier Science B.V. All rights reserved.
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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 0304-8853 ISBN Medium
Area Expedition Conference
Notes ISI:000085772100006 Approved no
Call Number BT @ hernan @ Serial 179
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Author Jaime, M.; Movshovich, R.; Stewart, G.R.; Beyermann, W.P.; Berisso, M.G.; Hundley, M.F.; Canfield, P.C.; Sarrao, J.L.
Title Closing the spin gap in the Kondo insulator Ce3Bi4Pt3 at high magnetic fields Type Journal Article
Year 2000 Publication (up) Nature Abbreviated Journal
Volume 405 Issue 6783 Pages 160-163
Keywords
Abstract Kondo insulator materials(1)-such as CeRhAs, CeRhSb, YbB12, Ce3Bi4Pt3 and SmB6-are 3d, 4f and 5f intermetallic compounds that have attracted considerable interest in recent years(2-5). At high temperatures, they behave like metals. But as temperature is reduced, an energy gap opens in the conduction band at the Fermi energy and the materials become insulating. This contrasts with other f-electron compounds, which are metallic at all temperatures. The formation of the gap in Kondo insulators has been proposed to be a consequence of hybridization between the conduction band and the f-electron levels(6,7), giving a 'spin' gap. If this is indeed the case, metallic behaviour should be recovered when the gap is closed by changing external parameters, such as magnetic field or pressure. Some experimental evidence suggests that the gap can be closed in SmB6 (refs 5, 8) and YbB12 (ref. 9). Here we present specific-heat measurements of Ce3Bi4Pt3 in d.c. and pulsed magnetic fields up to 60 tesla. Numerical results and the analysis of our data using the Coqblin-Schrieffer model demonstrate unambiguously a field-induced insulator-to-metal transition.
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Corporate Author Thesis
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836 ISBN Medium
Area Expedition Conference
Notes ISI:000087080100043 Approved no
Call Number BT @ hernan @ Serial 300
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Author Marconi, V. I.; Candia, S.; Balenzuela, P.; Pastoriza, H.; Domínguez, D.; Martinoli, P.
Title Orientational pinning and transverse voltage: Simulations and experiments in square Josephson junction arrays Type Journal Article
Year 2000 Publication (up) Phys. Rev. B Abbreviated Journal
Volume 62 Issue 6 Pages 4096-4104
Keywords
Abstract We study the dependence of the transport properties of square Josephson Junctions arrays with the direction of the applied dc current, both experimentally and numerically. We present computational simulations of current-voltage curves at finite temperatures for a single vortex in an array of $L\times L$ junctions ($Ha^2/?_0=f=1/L^2$), and experimental measurements in $100\times1000$ arrays under a low magnetic field corresponding to $f\approx0.02$. We find that the transverse voltage vanishes only in the directions of maximum symmetry of the square lattice: the [10] and [01] direction (parallel bias) and the [11] direction (diagonal bias). For orientations different than the symmetry directions, we find a finite transverse voltage which depends strongly on the angle φ of the current. We find that vortex motion is pinned in the [10] direction ($?=0$), meaning that the voltage response is insensitive to small changes in the orientation of the current near $?=0$. We call this phenomenon orientational pinning. This leads to a finite transverse critical current for a bias at $?=0$ and to a transverse voltage for a bias at $?\not=0$. On the other hand, for diagonal bias in the [11] direction the behavior is highly unstable against small variations of φ, leading to a rapid change from zero transverse voltage to a large transverse voltage within a few degrees. This last behavior is in good agreement with our measurements in arrays with a quasi-diagonal current drive.
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Notes Approved no
Call Number BT @ hernan @ marconi00 Serial 26
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Author Pastoriza, H.; Candia, S.; Nieva, G.
Title Anisotropic vortex dynamics in twined YBaCuO single crystals Type Journal Article
Year 2000 Publication (up) Physica B Abbreviated Journal
Volume 284-288 Issue 2 Pages 763-764
Keywords
Abstract Rotating continuously the applied vortex force and measuring the vortex velocity vector, we were able to directly determine the role of twin boundaries in the vortex dynamics in YBa$2$Cu$3Ο_7$ single crystals with unidirectional twins. We show the different effect of these correlated pinning defects into the various vortex phases. In the entangled vortex liquid state, we observe a linear response but with an anisotropic viscosity. On the other hand, an anomalous guided motion by twin planes is found in the vortex solid.
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Notes Approved no
Call Number BT @ hernan @ pastoriza00 Serial 39
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Author Sereni, J.G.
Title Evanescence of magnetic transitions in Ce systems Type Journal Article
Year 2000 Publication (up) Physica B – Condensed Matter Abbreviated Journal Physica B
Volume 281-282 Issue Pages 337-339
Keywords
Abstract Three types of magnetic phase diagrams can be identified in Ce systems: (I) with ordering temperature T-ord --> 0 continuously, followed by a narrow non-Fermi-liquid (NFL) region, (II) with T-ord vanishing at finite temperature, followed by an extended NFL region, and (III) where the degrees of freedom condensed into the ordered phase decreases, without a concomitant decrease of T-ord. Intrinsic differences are found in the way that the degrees of freedom condense at T-ord and from the rising of the specific heat tails above T-ord. (C) 2000 Elsevier Science B.V. All rights reserved.
Address
Corporate Author Thesis
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526 ISBN Medium
Area Expedition Conference
Notes ISI:000086570200141 Approved no
Call Number BT @ hernan @ Serial 79
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Author André, M-O.; Polichetti, M.; Pastoriza, H.; Kes, P. H.
Title Vortex dynamics in 2H-NbSe$_2$ containing a periodic channel structure Type Journal Article
Year 2000 Publication (up) Physica C Abbreviated Journal
Volume 338 Issue Pages 179-188
Keywords
Abstract We have measured the resistivity and magnetic AC susceptibility of 2H-NbSe single crystals containing alternating 2 stripes of irradiated and non-irradiated regions of columnar defects created by heavy-ion bombardment. Without applied magnetic field, the sample undergoes a double-step transition into the superconducting state, each step corresponding to the transitions in the irradiated and non-irradiated regions, respectively. For fields smaller than half of the matching field and upon increasing the temperature, the onset of flux motion in the non-irradiated channels occurs, when the applied stress due to the electrical current equals the shear stress at the channel edges, while depinning in the irradiated stripes occurs at higher temperature. The weak amplitude dependence of the shear process suggests that it takes place at the melting transition. We observed only a single-step transition at DC magnetic fields larger than half the matching field, because pinning by the columnar defects in the irradiated stripes is much less effective, and consequently the shear stress at the channel edges is strongly reduced. The comparison between the shear stress deduced from I curves and the theoretical value $?max = AC66$ yields a value for the constant Α, which is in good agreement with theoretical predictions.
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Notes Approved no
Call Number BT @ hernan @ andre99 Serial 2
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Author Pedrazzini, P.; Schmerber, G.; Berisso, M.G.; Kappler, J.P.; Sereni, J.G.
Title Magnetic and superconducting properties of A(7)B(3) compounds (A = Th or La and B=Ni, Co, Fe or Pd, Rh, Ru) Type Journal Article
Year 2000 Publication (up) PHYSICA C Abbreviated Journal
Volume 336 Issue 1-2 Pages 10-18
Keywords
Abstract High-temperature magnetization, low temperature specific heat, and ac-susceptibility measurements on Th7X3 (X = Ni, Co, and Fe) and La(7)Z(3) (Z = Pd, Rh, and Ru) superconductors are presented. The magnetic behaviour of the Th7X3 group has the characteristics of Pauli paramagnets. The La(7)Z(3) group also shows Pauli paramagnetism for Z = Pd and Ru, and signs of spin fluctuations for La7Rh3. Specific heat (C-p) measurements indicate a conventional BCS behaviour for La7Pd3 and La7Rh3, like that of the previously measured Th7X3 superconductors. in the case of La7Ru3, the reduced specific heat jump at the transition, the anomalous temperature dependence of C-p under magnetic field and a large upper critical field slope are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.
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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 0921-4534 ISBN Medium
Area Expedition Conference
Notes ISI:000088047500002 Approved no
Call Number BT @ hernan @ Serial 78
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