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Author (up) Civale, L.; Pasquini, G.; Levy, P.; Nieva, G.; Casa, D.; Lanza, H. openurl 
  Title Time relaxation of persistent currents in YBa2Cu3O7−x crystals with columnar defects Type Journal Article
  Year 1996 Publication Physica C: Superconductivity Abbreviated Journal Physica C  
  Volume 263 Issue 1-4 Pages 389-395  
  Keywords  
  Abstract We have measured the persistent currents and their time relaxation in YBa2Cu3O7−x single crystals with correlated disorder introduced by irradiation with high-energy heavy-ions. For vortex density lower than the defect density, and for applied fields either parallel or nonparallel to the columnar defects, we find clear evidence of a pinning-crossover between a regime of strong individual pinning at low temperatures and a regime of weaker collective pinning at high temperatures. We explore the vortex dynamics above and below this crossover.  
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  Call Number BT @ gnieva @ Serial 455  
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Author (up) Civale, L.; Pasquini, G.; Levy, P.; Nieva, G.; Lanza, H. isbn  openurl
  Title AC susceptibility of pinned vortices in YBa2Cu3O7 crystals with correlated disorder Type Journal Article
  Year 1996 Publication Advances in Superconductivity: VIII: Proceedings of the 8th International Symposium on Superconductivity Abbreviated Journal  
  Volume Issue Pages 553  
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  Abstract  
  Address  
  Corporate Author Thesis  
  Publisher Springer-Verlag Place of Publication Tokyo Editor Hayakawa, Hisao; Enomoto, Y.;  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
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  ISSN ISBN 4431701834 Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ gnieva @ Serial 460  
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Author (up) Herbsommer, J.A.; Luzuriaga, J.; Civale, L.; Nieva, G.; Pasquini, G.; Lanza, H.; Levy, P. url  openurl
  Title Angular variation of pinning near the irreversibility temperature in single crystal Y Ba2Cu3O7-? with splayed columnar defects Type Journal Article
  Year 1998 Publication Physica C Abbreviated Journal Physica C  
  Volume 304 Issue 1-2 Pages 112-118  
  Keywords Columnar defects; Critical current density; Flux pinning; Pinning force; Anisotropy; Critical current density (superconductivity); Crystal defects; Single crystals; Columnar defects; Flux pinning; Yttrium barium copper oxides  
  Abstract We have studied vortex pinning through ac susceptibility measurements in single crystals of YBCO with columnar defects (CDs). The CDs have 0, 10 and 20 splay angle and average direction 108 off the c-axis. By studying the angular variation we can compensate for the anisotropy and effects of twins, etc. Using a simple expression we can obtain the angular spread when the field direction is outside the splay angle. An increase of pinning when the field direction is inside

the angle defined by the CDs can be attributed to vortex entanglement due to the splay and the suppression of the sliding of double kinks.
 
  Address Departamento de F  
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  ISSN 09214534 (ISSN) ISBN Medium  
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  Notes Cited By (since 1996): 10; Export Date: 28 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Herbsommer, J.A.; Ctro. Atom. Bariloche Inst. Balseiro; CNEA and UNC 8400 Bariloche, Argentina; References: Civale, L., Marwick, A.D., Worthington, T.K., Kirk, M.A., Thompson, J.R., Krusin-Elbaum, L., Sun, Y., Holtzberg, F., (1991) Phys. Rev. Lett., 67, p. 648; Hwa, T., Doussal, P.L., Nelson, D.R., Vinokur, V.M., (1993) Phys. Rev. Lett., 71, p. 3545; Civale, L., Krusin-Elbaum, L., Thompson, J.R., Wheeler, R., Marwick, A.D., Kirk, M.A., Sun, Y.R., (1994) Phys. Rev. B, 50, p. 4102; Krusin-Elbaum, L., Thompson, J.R., Wheeler, R., Marwick, A.D., Li, C., Patel, S., Shaw, D.T., Ullmann, J., (1994) Appl. Phys. Lett., 64, p. 3331; Hardy, V., Whal, A., Hebert, S., Ruyler, A., Provost, J., Groult, D., Simon, C., (1996) Phys. Rev. B, 54, p. 656; Hardy, V., Ruyter, A., Whal, A., Maignan, A., Groult, D., Provost, J., Simon, C., Noel, H., (1996) Physica C, 257, p. 16; Krusin-Elbaum, L., Marwick, A.D., Wheeler, R., Feild, C., Vinokur, V.M., Leaf, G.K., Palumbo, M., (1996) Phys. Rev. Lett., 76, p. 2563; Prozorov, R., Konczykowski, M., Schmidt, B., Yeshurun, Y., Shaulov, A., Villard, C., Koren, G., (1996) Phys. Rev. B, 54, p. 15530; De La Cruz, F., L Approved no  
  Call Number BT @ luzuriag @ Serial 517  
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Author (up) Pasquini, G.; Civale, L.; Lanza, H.; Nieva, G. openurl 
  Title Angular regimes of ac dynamics and pinning in YBa2Cu3O7 crystals with and without columnar defects Type Journal Article
  Year 2002 Publication PHYSICAL REVIEW B Abbreviated Journal  
  Volume 65 Issue 21 Pages 214517  
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  Abstract The main source of vortex pinning near the solid-liquid transition at different orientations of a low dc field in YBa2Cu3O7 crystals with columnar defects is investigated by means of ac susceptibility measurements. The behavior is compared with that observed in nonirradiated samples. It is found that in a very wide angular region the tracks act as correlated defects and are the prevailing source of pinning. The results rule out the existence of an accommodation angle, determined by the competition between the pinning and elastic energies, in twined crystals: the interplay with natural correlated pinning centers has to be taken into account. The linear and nonlinear dynamic regimes when the field is tilted relative to the defects are analyzed. It is clearly shown that characterization of the dynamic regimes is crucial for the correct interpretation of the angular dependence in the ac response.  
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  Series Volume Series Issue Edition  
  ISSN 1098-0121 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000176765700106 Approved no  
  Call Number BT @ hernan @ Serial 210  
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Author (up) Pasquini, G.; Civale, L.; Lanza, H.; Nieva, G. openurl 
  Title Dynamic regimes in the ac response of YBa2Cu3O7 with columnar defects: Intra- and inter-valley vortex motion Type Journal Article
  Year 1999 Publication PHYSICAL REVIEW B Abbreviated Journal  
  Volume 59 Issue 14 Pages 9627-9636  
  Keywords  
  Abstract We use ac susceptibility measurements to explore the dynamic response of vortices in YBCO single crystals pinned by aligned columnar defects at low de fields. Using a combination of techniques for the analysis of the data, we investigate the vortex motion as a function of the amplitude and frequency of the applied ac field h(ac), identifying the influence of both intra- and inter-valley motion. We build up a dynamic diagram in the h(ac)-T plane indicating the crossover lines among several regimes in the solid phase. At low h(ac), a linear response with very low dissipation arises from the oscillation of pinned vortices inside the tracks (Campbell regime). At high h(ac) a critical state develops. The large influence of thermal fluctuations in this limit is indicated by the frequency dependence, which allows us to obtain the current density dependence of the activation energy and the glassy exponent. We also discuss the origin of the large nonlinear transition regime observed at intermediate amplitudes. [S0163-1829(99)02613-2].  
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  ISSN 0163-1829 ISBN Medium  
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  Notes ISI:000079754300073 Approved no  
  Call Number BT @ hernan @ Serial 234  
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Author (up) Pasquini, G.; Levy, P.; Civale, L.; Nieva, G.; Lanza, H. doi  openurl
  Title Linear response in the AC susceptibility of vortices in YBa2Cu3O7 crystals with columnar defects Type Journal Article
  Year 1997 Publication Physica C: Superconductivity Abbreviated Journal  
  Volume 274 Issue 1-2 Pages 165-172  
  Keywords  
  Abstract We explore the AC magnetic susceptibility of YBa2Cu3O7 single crystals with columnar defects. For vortices parallel to the defects the linear response is mainly determined by the Campbell penetration depth with a field independent Labusch parameter indicating that vortices are individually pinned. The small dissipation in this limit is likely to arise from thermal fluctuations of vortex segments between pairs of metastable states (two-level systems) in the Bose glass phase. Tilting vortices away from the tracks results in a reduction of the Bose glass temperature and an increase of the dissipation due to the reduction of the pinning forces. We discuss the onset of nonlinear response as the AC field increases.  
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  Series Volume Series Issue Edition  
  ISSN 0921-4534 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:A1997WG88200021 Approved no  
  Call Number BT @ hernan @ Serial 243  
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Author (up) Silhanek, A.; Civale, L.; Candia, S.; Nieva, G.; Pasquini, G.; Lanza, H. openurl 
  Title Evidence for vortex staircases in the whole angular range due to competing correlated pinning mechanisms Type Journal Article
  Year 1999 Publication PHYSICAL REVIEW B Abbreviated Journal  
  Volume 59 Issue 21 Pages 13620-13623  
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  Abstract We present measurements of the angular dependence of the irreversible magnetization of YBa2Cu3O7 single crystals with columnar defects inclined with respect to the c axis. At high fields a sharp maximum centered at the tracks direction is observed. At low fields we identify a lock-in phase characterized by an angle-independent pinning strength and observe an angular shift of the peak towards the c axis that originates in the misalignment between vortices and applied field in anisotropic materials. The interplay among columnar defects, twins, and intrinsic pinning by the ab planes generates a variety of staircase structures. We show that correlated pinning dominates for all orientations of the applied field. [S0163-1829(99)09417-5].  
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  Series Volume Series Issue Edition  
  ISSN 0163-1829 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000080778700035 Approved no  
  Call Number BT @ hernan @ Serial 233  
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Author (up) Silhanek, K.; Guimpel, J.; Civale, L.; Lanza, H.; Levy, P. openurl 
  Title Thickness effects on the pinning by columnar defects Type Journal Article
  Year 2000 Publication PHYSICA C Abbreviated Journal  
  Volume 341 Issue Pages 1217-1218  
  Keywords  
  Abstract We compare the angular dependence of the pinning of equivalent columnar defects in GdBa2Cu2O7 thin films and a thicker YBa2Cu3O7 single crystal. The tracks' related enhancement of the critical currents is much smaller for the case of the thin films. We interpret this thickness dependence as resulting from a competition between the pinning of the correlated structures, related to total sample thickness, and surface boundary conditions, which force the vortices to depin from the columnar defects near the sample surface.  
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  Series Volume Series Issue Edition  
  ISSN 0921-4534 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000165855700208 Approved no  
  Call Number BT @ hernan @ Serial 175  
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