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Author Luzuriaga, J.
Title Measurements in the laminar and turbulent regime of superfluid4He by means of an oscillating sphere Type Journal Article
Year 1997 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume (down) 108 Issue 3-4 Pages 267-277
Keywords Calculations; Laminar flow; Oscillations; Spheres; Turbulence; Turbulent flow; Vibrations (mechanical); Oscillating sphere; Translational oscillation; Superfluid helium
Abstract The translational oscillations of a sphere in liquid helium have been measured as a way of studying superfluid turbulence. Experiments were carried out in the laminar flow regime for reference purposes, and good agreement found between measured and calculated quantities. In the turbulent region, the dissipation is found to be proportional to the square of the velocity of the sphere, as found previously by other workers. For high vibration amplitudes there is an increase in the hydrodynamic mass. This seems to scale with the superfluid fraction in a way that strongly suggests that the superfluid component plays an important role in the turbulent regime.
Address Comisi
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ISSN 00222291 (ISSN) ISBN Medium
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Notes Cited By (since 1996): 2; Export Date: 28 April 2009; Source: Scopus; CODEN: JLTPA; Language of Original Document: English; Correspondence Address: Luzuriaga, J.; Comisi Approved no
Call Number BT @ luzuriag @ Serial 518
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Author Rodriguez, E.; Luzuriaga, J.; Núñez Regueiro, M.; Fainstein, C.
Title Low temperature internal friction peak in high Tc superconductors Type Journal Article
Year 1991 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume (down) 77 Issue 10 Pages 777-780
Keywords Ceramic Materials; Oxides – Acoustic Properties; Yttrium Compounds – Acoustic Properties; Acoustic Variables Measurement; Attenuation Peak; Calcium Compounds; Low Temperature Internal Friction Peak; Strontium Compounds; Thermally Activated Relaxation Behavior; High Temperature Superconductors
Abstract We measure the internal friction Q-1 in YBa2Cu3O7-x and Bi2Sr2CaCu2O8+x samples. At temperatures near 35 K for KHz frequencies we observe an attenuation peak. In the case of YBa2Cu3O7-x, assuming a thermally activated relaxation behaviour, we are able to show that it corresponds to the same process as other peaks observed at higher frequencies. For Bi2Sr2CaCu2O8+x this is not the case, and the origin of the peak, found in all the measured samples, remains unknown.
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ISSN 0038-1098 ISBN Medium
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Notes ISI:A1991FA71400006 Approved no
Call Number BT @ hernan @ Serial 256
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Author Luzuriaga, J.
Title Comment on “Super classical quantum mechanics: The best interpretation of nonrelativistic quantum mechanics” Type Journal Article
Year 2002 Publication American Journal of Physics Abbreviated Journal Am. J. Phys.
Volume (down) 70 Issue 1 Pages 10-10
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ISSN 0002-9505 ISBN Medium
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Notes ISI:000172959200001 Approved no
Call Number BT @ hernan @ Serial 245
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Author Herbsommer, J.A.; Nieva, G.; Luzuriaga, J.
Title Interplay between pinning energy and vortex interaction in YBa2Cu3O7-delta with oriented twin boundaries in tilted magnetic fields: Bitter decoration and tilt-modulus measurements Type Journal Article
Year 2000 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume (down) 62 Issue 5 Pages 3534-3541
Keywords
Abstract We have performed Bitter decoration and ac susceptibility measurements in single-crystal YBa2Cu3O7-delta with oriented twin boundaries. The twin boundaries (TB's) pin vortices over approximately 65% of the sample. The pinned areas are unevenly distributed and some relatively large TB-free regions are present. The Bitter decorations were performed in a 52 Oe de magnetic field rotated off the c axis so that the plane defined by the field direction and the c axis is perpendicular to the TB's. Several decorations were performed in the same sample. Additional dynamical information was obtained from ac susceptibility measurements. Results show that for small tilts the vortices remain locked to the c-axis direction, for angles greater than 12 degrees they form a staircase pattern, and in this case pinning by the twin boundaries remains effective up to 75 degrees. We observe vortex chains in twin-free-zones of the sample for tilted fields at 65 degrees and 40 degrees. Due to our particular experimental arrangement, in the twinned regions the interplay of the potentials giving rise to the chains and the pinning potential produces a structure with a disordered square symmetry. The data allow us to estimate the dominant energy of the vortex system for some inclinations of the applied magnetic field.
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Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes ISI:000088714200086 Approved no
Call Number BT @ hernan @ Serial 224
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Author Herbsommer, J.A.; Nieva, G.; Luzuriaga, J.
Title Repetition of the disordered pattern in successive solidifications of vortex matter observed by Bitter decoration Type Journal Article
Year 2000 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume (down) 62 Issue 1 Pages 678-681
Keywords
Abstract Repeated images of the vortex structure in YBa2Cu3O7-delta Single crystals have been obtained, using the Bitter technique. By removing the iron dots between each decoration experiment, it is possible to image the vortices in different cooldown runs done under the same field and temperature conditions. The images show that these different realizations of a disordered vortex state found in twinned crystals are very similar at long range and differ only in small-scale detail. This is unusual behavior in glassy systems, where expectations are that successive configurations will differ over many scales. In contrast, ordered vortex crystals in clean samples can form with different orientations in different runs, therefore differing at long ranges. Double-sided decorations have been performed in twinned samples, and the correlation between images in both sides of the sample is similar in magnitude but slightly different qualitatively than that found in successive decorations.
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ISSN 0163-1829 ISBN Medium
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Notes ISI:000088037000106 Approved no
Call Number BT @ hernan @ Serial 225
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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 (down) 61 Issue 17 Pages 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
Area Expedition Conference
Notes ISI:000086937700090 Approved no
Call Number BT @ hernan @ Serial 228
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Author 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 (down) 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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ISSN 0002-9505 ISBN Medium
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Notes ISI:A1990EJ58300010 Approved no
Call Number BT @ hernan @ Serial 258
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Author Luzuriaga, J.
Title Even in translation, Richter's 'science' unimpressive Type Journal Article
Year 2005 Publication Physics Today Abbreviated Journal Phys Today
Volume (down) 58 Issue 1 Pages 14-15
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Address Instituto Balseiro, Bariloche, Argentina
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ISSN 00319228 (ISSN) ISBN Medium
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Notes Export Date: 28 April 2009; Source: Scopus; CODEN: PHTOA; doi: 10.1063/1.1881878; Language of Original Document: English; Correspondence Address: Luzuriaga, J.; Centro Atomico Bariloche Bariloche, Argentina Approved no
Call Number BT @ luzuriag @ Serial 508
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Author Luzuriaga, J.; D'Ovidio, C.; de la Cruz, F.
Title Ideal two dimensional flux pinning induced by annealing in superconducting amorphous Zr75Rh25 Type Journal Article
Year 1986 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume (down) 57 Issue 9 Pages 753-756
Keywords ZIRCONIUM COMPOUNDS – Physical Properties; CRITICAL CURRENT; FLUX PINNING; MELT SPINNING; PINNING FORCES; SUPERCONDUCTING MATRIX; SUPERCONDUCTING MATERIALS
Abstract By annealing amorphous Zr75Rh25 prepared by melt spinning an ideal behaviour of the critical current was observed, in which the measured pinning forces are seen to follow the two dimensional Larkin-Orchivnikov theory. In the region where this theory is valid the changes in the pinning forces can be explained by the changes in the superconducting matrix and it can be assumed that the pinning centers do not change with the heat treatment.
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 00381098 (ISSN) ISBN Medium
Area Expedition Conference
Notes Export Date: 28 April 2009; Source: Scopus; CODEN: SSCOA; Language of Original Document: English; Correspondence Address: Luzuriaga, J.; Centro Atomico Bariloche; Instituto Balseiro 8400 Bariloche, Argentina Approved no
Call Number BT @ luzuriag @ Serial 501
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Author Arce, R.; Civale, L.; Luzuriaga, J.; Guimpel, J.; de la Cruz, F.
Title Surface normal regions in superconducting Zr70Cu30 induced by thermal relaxation Type Journal Article
Year 1983 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume (down) 48 Issue 12 Pages 1027-1030
Keywords ZIRCONIUM COPPER ALLOYS – Physical Properties; SUPERCONDUCTING MATERIALS
Abstract Penetration depth measurements show that thermal heat treatment in amorphous Zr70Cu30 induces a normal region 5000 Å thick at the surface of ultrarapid quenched ribbons. Upper critical field measurements indicate that the new induced phase is a normal one while the rest of the sample remains as a homogeneous superconducting phase.
Address Centro Atómico Bariloche – Instituto Balseiro
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 00381098 (ISSN) ISBN Medium
Area Expedition Conference
Notes Export Date: 28 April 2009; Source: Scopus; CODEN: SSCOA; Language of Original Document: English; Correspondence Address: Arce, R.; Centro At Approved no
Call Number BT @ luzuriag @ Serial 502
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