| Records |
| 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 |
62 |
Issue |
1 |
Pages |
678-681 |
| Keywords |
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| 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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Series Issue  |
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Edition |
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| ISSN |
0163-1829 |
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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 |
61 |
Issue |
17 |
Pages |
11745-11751 |
| Keywords |
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| 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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Edition |
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| ISSN |
1098-0121 |
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| Notes |
ISI:000086937700090 |
Approved |
no |
| Call Number |
BT @ hernan @ |
Serial |
228 |
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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 |
Nature |
Abbreviated Journal |
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| Volume |
405 |
Issue |
6783 |
Pages |
160-163 |
| Keywords |
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| 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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| ISSN |
0028-0836 |
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| Notes |
ISI:000087080100043 |
Approved |
no |
| Call Number |
BT @ hernan @ |
Serial |
300 |
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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 |
Journal of Alloys and Compounds |
Abbreviated Journal |
J Alloys Compd |
| Volume |
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Issue |
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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 |
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| Publisher |
Elsevier Sequoia SA |
Place of Publication |
Buenos Aires, Argent |
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12th International Conference on Internal Friction and Ultrasonic Attenuation in Solids (ICIFUAS-12) |
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| Series Volume |
310 |
Series Issue |
1-2 |
Edition |
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| ISSN |
09258388 (ISSN) |
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| 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 |
| Permanent link to this record |
