| Records |
Author  |
Bahrs, S.; Bruchhausen, A.; Goni, A.R.; Nieva, G.; Fainstein, A.; Fleischer, K.; Richter, W.; Thomsen, C. |
| Title |
Effect of light on the reflectance anisotropy and chain-oxygen related Raman signal in untwinned, underdoped crystals of YBa2Cu3O7-delta |
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Journal Article |
| Year |
2006 |
Publication |
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS |
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| Volume |
67 |
Issue |
1-3 |
Pages |
340-343 |
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| Abstract |
Recent studies of the optical anisotropy of a detwinned, underdoped YBa2Cu3O7-delta-crystal showed that illumination-induced change and recovery in the surface reflectance can be traced on a time scale of hours. This effect of light is also known from Raman bleaching and electrical transport and shares features of the oxygen reordering processes above room temperature. We report temperature-dependent studies of the optical anisotropy using reflectance anisotropy spectroscopy and present time-dependent data for the optical transitions at 2.2 and 4.4 eV. We compare our results to Raman bleaching and discuss them within the picture of superstructure patterns and oxygen-defect reordering in underdoped YBa2Cu3O7-delta. (c) 2005 Elsevier Ltd. All rights reserved. |
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0022-3697 |
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ISI:000236746600084 |
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BT @ hernan @ |
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203 |
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| Author |
Bahrs, S.; Muller, S.; Rubhausen, M.; Schulz, B.; Goni, A.R.; Nieva, G.; Thomsen, C. |
| Title |
Anisotropic ultraviolet raman resonance in underdoped YBa2Cu3O6.7 |
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Journal Article |
| Year |
2006 |
Publication |
PHYSICAL REVIEW B |
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| Volume |
74 |
Issue |
2 |
Pages |
024519 |
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We report an inverse Raman-bleaching anomaly of oxygen-vacancy-activated phonons in underdoped YBa2Cu3O6.7 excited in resonance at 4.1 eV. These modes are closely related to modes that photobleach under visible excitation. The resonance and selection rules match the prediction from the ab in-plane anisotropy of the dielectric function, as does their growth of intensity under illumination. These properties support the oxygen-vacancy-reordering model for photoinduced changes in underdoped YBa2Cu3O7-delta. We suggest that a similar coupling to anisotropic electronic resonances is responsible for the recently discovered ab anisotropies in the phonon dispersion. |
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1098-0121 |
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ISI:000239426600091 |
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BT @ hernan @ |
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202 |
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Deppe, M.; Pedrazzini, P.; Caroca-Canales, N.; Gelbel, C.; Sereni, J.G. |
| Title |
Investigations of CePd1-xRhx single crystals located near a ferromagnetic quantum critical point |
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Journal Article |
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2006 |
Publication |
PHYSICA B-CONDENSED MATTER |
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378-380 |
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96-97 |
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Investigations of CePd1-xRhx polycrystals have revealed a continuous transition from a ferromagnetic state at x = 0 to an intermediate valence state at x = 1 and evidenced non-Fermi liquid behavior near the critical concentration x(c) approximate to 0.85 where T-C is continuously suppressed to T = 0 K. We present here first results of specific heat and magnetization measurements on CePd1-xRhx single crystals with composition close to the critical point. They confirm the results obtained on polycrystals and reveal a rather low magnetic anisotropy, despite the orthorhombic structure. (c) 2006 Elsevier B.V. All rights reserved. |
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0921-4526 |
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ISI:000238426600033 |
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BT @ hernan @ |
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56 |
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Fasano, Y.; Seta, M.D.; Menghini, M.; Pastoriza, H.; Cruz, F. de la |
| Title |
Effect of vortex dimensionality on elastic and plastic symmetry transformations induced in vortex matter |
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Journal Article |
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2006 |
Publication |
Journal of Physics and Chemistry of Solids |
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67 |
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395-398 |
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We analyse the role played by vortex dimensionality in structural transformations induced at the surface of bulk Bi$2$Sr$2$CaCu$2Ο8$ (extremely anisotropic) and NbSe$2$ (moderately anisotropic) vortex crystals interacting with two-dimensional square pinning structures. The observation of alternating floating and distorted hexagonal domains induced in the NbSe$2$ vortex structure contrasts with the square one induced in Bi$2$Sr$2$CaCu$2Ο8$. Despite vortex-vortex interaction energy being similar in both materials, the different elastic characteristics and the dissimilar vortex solidification mechanisms are responsible for the plastic and elastic structural transformations detected in Bi$2$Sr$2$CaCu$2Ο8$ and NbSe$_2$, respectively. |
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BT @ hernan @ fasano05 |
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20 |
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Giordano, J.L.; Luzuriaga, J.; Badía-Majós, A.; Nieva, G.; Ruiz-Tagle, I. A. |
| Title |
Magnetization collapse in polycrystalline YBCO under transport current cycles |
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Journal Article |
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2006 |
Publication |
Superconducting Science and Technology |
Abbreviated Journal |
Supercond. Sci. Technol. |
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19 |
Issue |
4 |
Pages |
385-391 |
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We report measurements of the hysteretic magnetization of YBCO under superimposed transport current cycles, together with numerical simulations of magnetization and current density profiles in the corresponding parallel configuration. Field cooled (FC) and zero-field-cooled (ZFC) experiments were carried out on polycrystalline YBa2Cu3O7?x cylinders, with both the applied magnetic field and transport current in the axial direction, and the current cycled several times, around and above the dissipative threshold. As in previously reported multicomponent field configuration experiments, the magnetization is seen to collapse to a more stable state both in FC and ZFC, because of the interplay between the shielding and transport currents. The results of our numerical simulations are in good qualitative agreement with the measurements, and the competition between shielding and transport due to vortex-pinning interactions and equilibrium magnetization effects are shown to play an important role in the range of our experiments. |
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0953-2048 |
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BT @ gnieva @ |
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467 |
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Giordano, J.L.; Luzuriaga, J.; Ruíz-Tagle,; NIEVA, G.; Badía-Majós, |
| Title |
Magnetization measurements of hard superconductors under dissipative transport |
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Journal Article |
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2006 |
Publication |
Journal of Physics: Conference Series |
Abbreviated Journal |
J. Phys. Conf. Ser. |
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43 |
Issue |
1 |
Pages |
663-666 |
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The hysteretic magnetic flux dynamics of ceramic type-II superconductors under superimposed transport current cycles has been investigated. Field cooled and zero field cooled experiments were carried-out on polycrystalline YBa 2Cu3O7-x cylinders by using both temperature and applied field control, to drive the sample into the semi-reversible granular regime. The transport current magnitude was near and above the dissipative threshold. The interplay between shielding and transport due to vortex-pinning interactions, equilibrium magnetization effects, and diamagnetic/paramagnetic relaxation phenomena are shown to play an important role in the range of practical applications. |
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17426588 (ISSN) |
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Export Date: 28 April 2009; Source: Scopus; Art. No.: 162; doi: 10.1088/1742-6596/43/1/162; Language of Original Document: English; Correspondence Address: Giordano, J.L.; Departamento de Ciencias de la Ingenier |
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BT @ luzuriag @ |
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471 |
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Gomez, M.E.; Campillo, G.; Ramirez, J.G.; Prieto, P.; Hoffmann, A.; Guimpel, J.; Haberkorn, N.; Condo, A.; Lovey, F. |
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Magnetotransport properties in epitaxial exchange-biased La2/3Ca1/3MnO3/La1/3Ca2/3MnO3 superlattices |
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Journal Article |
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2006 |
Publication |
IEEE Transactions on Magnetics |
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IEEE Trans. Magn. |
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42 |
Issue |
10 |
Pages |
2981-2983 |
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Superlattices of ferromagnetic (F) and antiferromagnetic (AF) oxide materials have attracted increased attention given the exchange bias or exchange anistropy phenomenon. Research on magnetic oxide superlattices has focused toward the technological goals of increasing magnetores stance in lower applied magnetic fields and more useful temperature ranges for various applications. Superlattices of F-LCMO and AF-LCMO layers were grown on (001)-oriented SrTiO3 substrates. We studied the temperature dependence of magnetotransport properties for a series of [AF-LCMO (7.6 nm)/F-LCMO (t(F))](N) superlattices as a function of the ferromagnetically doped layer thickness, t(F), while the antiferromagnetic (AF) layer thickness, t(AF), was kept constant. Magnetotransport measurements at different temperatures were done on a series of [AF(7.6 nm)IF(t(F))](N) superlattices. The ZFC resistance has a maximum at negative fields, for all multilayers, with descending fields (from 1 to -1 kOe). In all samples a shift along the field axis of the FC loop with respect to that of the ZFC loop is observed. The H-ex values determined from these displacements of the FC loops of the magnetoresistance loops increase when temperature decreases and its magnitude also depends on the ferromagnetic layer thickness. |
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0018-9464 |
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ISI:000240888700241 |
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BT @ hernan @ |
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153 |
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Gonzalez, E.M.; Sefrioui, Z.; Maiorov, B.; Osquiguil, E.; Santamar |
| Title |
Effects of structural microdomains on the vortex correlation length in a-axis oriented EuBa2Cu3O7 thin films |
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Journal Article |
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2006 |
Publication |
Journal of Physics and Chemistry of Solids |
Abbreviated Journal |
J Phys Chem Solids |
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67 |
Issue |
1-3 |
Pages |
399-402 |
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A. Superconductors; A. Thin films; B. Epitaxial growth; D. Superconductivity; D. Transport properties; Activation energy; Anisotropy; Epitaxial growth; Europium compounds; Magnetron sputtering; Superconductivity; Thin films; Transport properties; Anisotropic superconductors; Domain boundaries; Structural microdomains; Vortex correlation; Superconducting materials |
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We have grown a-axis oriented EuBa2Cu3O7 thin films on SrTiO3 (001) substrates using a magnetron sputtering technique. In these films the CuO2 planes are aligned parallel to the substrates. The film microstructure shows microdomains. The microdomains are grains with a 90 |
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00223697 (ISSN) |
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Export Date: 17 April 2009; Source: Scopus; CODEN: JPCSA; doi: 10.1016/j.jpcs.2005.10.093; Language of Original Document: English; Correspondence Address: Vicent, J.L.; Departamento F |
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BT @ osquigui @ |
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364 |
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Hoffmann, A.; Nieva, G.; Guimpel, J.; Bruynseraede, Y.; Santamaria, J.; Lederman, D.; Schuller, I.K. |
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Comment on “Photoemission study of YBa2Cu3Oy thin films under light illumination” |
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Journal Article |
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2006 |
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PHYSICAL REVIEW LETTERS |
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| Volume |
97 |
Issue |
11 |
Pages |
119701 |
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0031-9007 |
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ISI:000240545600075 |
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BT @ hernan @ |
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154 |
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Kasama, T.; Moreno, M.S.; Dunin-Borkowski, R.E.; Newcomb, S.B.; Haberkorn, N.; Guimpel, J.; Midgley, P.A. |
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Characterization of the magnetic properties of a GdBa2Cu3O7/La0.75Sr0.25MnO3 superlattice using off-axis electron holography |
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Journal Article |
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2006 |
Publication |
Applied Surface Science |
Abbreviated Journal |
Appl. Surf. Sci. |
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252 |
Issue |
11 |
Pages |
3977-3983 |
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Off-axis electron holography is used to characterize the magnetic properties of a GdBa2Cu3O7/La0.75Sr0.25MnO3 superlattice below the Curie temperature of the manganite layers, in both cross-sectional and plan-view geometry. The samples were prepared for electron microscopy using focused ion beam milling. Differences between the magnetic properties of successive manganite layers are observed in the cross-sectional sample. Magnetic ripple contrast and weakly magnetic regions are observed in plan-view geometry. Although the results may be affected by sample preparation for electron microscopy, the observed differences between the magnetic properties of the manganite layers are consistent between the different samples examined. (c) 2005 Elsevier B.V. All rights reserved. |
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0169-4332 |
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ISI:000236835200013 |
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BT @ hernan @ |
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155 |
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