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Author Haberkorn, N.; Guimpel, J.; Sirena, M.; Steren, L.B.; Saldarriaga, W.; Baca, E.; Gomez, M.E.
Title Antiferromagnetism at the YBa2Cu3O7/La2/3Ca1/3MnO3 interface Type Journal Article
Year 2004 Publication (up) Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume 84 Issue 19 Pages 3927-3929
Keywords
Abstract The magnetic properties of a series of YBa2Cu3O7-x/La2/3Ca1/3MnO3 (YBCO/LC1/3MO) superlattices grown by dc sputtering at high oxygen pressures (3.5 mbar) show the expected ferromagnetic behavior. However, field-cooled hysteresis loops at a low temperatures show the unexpected existence of exchange bias effect associated with the existence of ferromagnetic/antiferromagnetic (AF) interfaces. The blocking temperature (T-B) is found to be thickness dependent and the exchange bias field (H-EB) is found to be inversely proportional to the ferromagnetic layer thickness, as expected. The presence of an AF material is probably associated with interface disorder and Mn valence shift toward Mn4+. (C) 2004 American Institute of Physics.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951 ISBN Medium
Area Expedition Conference
Notes ISI:000221210100069 Approved no
Call Number BT @ hernan @ Serial 165
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Author Sirena, M.; Kaul, E.; Pedreros, M.B.; Rodriguez, C.A.; Guimpel, J.; Steren, L.B.
Title Structural, magnetic and electrical properties of ferromagnetic/ferroelectric multilayers Type Journal Article
Year 2011 Publication (up) Journal of Applied Physics Abbreviated Journal J. Appl. Phys.
Volume 109 Issue 12 Pages 123920
Keywords atomic force microscopy; barium compounds; electrical conductivity; ferroelectric materials; ferromagnetic materials; lanthanum compounds; magnetic multilayers; magnetisation; multiferroics; sputter deposition; strontium compounds; superlattices; texture; tunnelling; X-ray diffraction
Abstract The La0.75Sr0.25MnO3 (LSMO)/Ba0.7Sr0.3TiO3 (BSTO) superlattices and bilayers, where LSMO is ferromagnetic and BSTO is ferroelectric, were grown by dc sputtering. X-ray diffraction indicates that the samples present a textured growth with the c axis perpendicular to the substrate. Magnetization measurements show a decrease of the sample’s magnetization for decreasing ferromagnetic thickness. This effect could be related to the presence of biaxial strain and a magnetic dead layer in the samples. Conductive atomic force microscopy indicates that the samples present a total covering of the ferromagnetic layer for a ferroelectric thickness higher than four unit cells. Transport tunneling of the carriers seems to be the preferred conduction mechanism through the ferroelectric layer. These are promising results for the development of multiferroic tunnel junctions.
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Corporate Author Thesis
Publisher Aip Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ jguimpel @ Serial 606
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Author Sirena, M.; Haberkorn, N.; Granada, M.; Steren, L.B.; Guimpel, J.
Title Metal-insulator transition induced by postdeposition annealing in low doped manganite films Type Journal Article
Year 2009 Publication (up) JOURNAL OF APPLIED PHYSICS Abbreviated Journal
Volume 105 Issue 3 Pages
Keywords
Abstract We studied the transport and magnetic properties of low-doped manganite films after different oxygenation processes. The oxygen content was adjusted by postdeposition annealing at different oxygen pressures and annealing times. For all the samples we observed an increase in the Curie temperature and the remnant magnetization with the oxygen content. In general, for decreasing number of oxygen vacancies, samples under expansive strain become more homogeneous and their electrical resistivity decreases. A metal-insulator transition is induced in highly oxygenated films grown on SrTiO3, probably related to a shift of the mobility edge crossing below the Fermi energy. We found that the oxygenation dynamics depend critically on the strain field induced by the substrates and also on the Sr doping concentration.
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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:000263409700057 Approved no
Call Number BT @ hernan @ Serial 143
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Author Haberkorn, N.; Guimpel, J.; Steren, L.B.; Campillo, G.; Saldarriaga, W.; Gomez, M.E.
Title Structure of high-T-c/manganite perovskite superlattices Type Journal Article
Year 2003 Publication (up) JOURNAL OF APPLIED PHYSICS Abbreviated Journal
Volume 94 Issue 5 Pages 3011-3014
Keywords
Abstract We study the crystalline and interface structure of RBa2Cu3O7/La(1-x)A(x)MnO(3) superlattices (R=Y, Gd; A=Ca, Sr) grown on mismatched MgO substrates by means of nondestructive x-ray diffraction. The diffraction patterns are adjusted to a model of the structure which includes interface roughness and interdiffusion. Our results show that these disorder mechanisms cannot be neglected and should be taken into account to understand the physical properties of these superlattice. (C) 2003 American Institute of Physics.
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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:000184844200032 Approved no
Call Number BT @ hernan @ Serial 167
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Author Sirena, M.; Haberkorn, N.; Granada, M.; Steren, L.B.; Guimpel, J.
Title Correlation between structure and magnetic properties of manganite-based multilayers Type Journal Article
Year 2003 Publication (up) JOURNAL OF APPLIED PHYSICS Abbreviated Journal
Volume 93 Issue 10 Pages 7244-7246
Keywords
Abstract We have studied the structure, magnetic, and transport properties of manganite-based multilayers A/B-i, with A=La0.55Sr0.45MnO3 (metallic ferromagnet), and spacers (B-i) of different nature: B-1=SrTiO3 (nonmagnetic insulator), B-2=La0.9Sr0.1MnO3 (insulator ferromagnet), and B-3=La0.67Ca0.33MnO3 (paramagnetic-insulator/ferromagnet-metal). The samples are strongly textured in the direction perpendicular to the sample surface, and present a good interface quality with small roughness and interdiffusion. We have found that in the A/B-1/A trilayers, the ferromagnetic electrodes are ferromagnetically coupled for thin spacer layers and becomes decoupled for spacer thickness larger than 3 nm. Instead, the others multilayers are ferromagnetic for all spacer thicknesses and temperature range. This result was expected for temperatures well below the spacer Curie temperature. We attributed the ferromagnetic behavior of the system, found for temperatures above the ordering temperature of the spacer, to direct exchange coupling through short-range ordered zones in spacer layer. As expected from magnetization results, in fact, no extrinsic magnetoresistance was measured in these systems in the temperature range between 4.2 and 300 K. (C) 2003 American Institute of Physics.
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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:000182822300273 Approved no
Call Number BT @ hernan @ Serial 168
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Author Sirena, M.; Haberkorn, N.; Steren, L.B.; Guimpel, J.
Title Magnetic coupling and magnetoresistance in La0.55Sr0.45MnO3/La0.67Ca0.33MnO3 multilayers Type Journal Article
Year 2003 Publication (up) JOURNAL OF APPLIED PHYSICS Abbreviated Journal
Volume 93 Issue 10 Pages 6177-6181
Keywords
Abstract We have studied the interlayer coupling and the magnetoresistant effect of La0.55Sr0.45MnO3/La0.67Ca0.33MnO3 structures. Magnetization loops, measured in La0.55Sr0.45MnO3/La0.67Ca0.33MnO3/La0.55Sr0.45MnO3 trilayers, indicate that there is a ferromagnetic coupling of the La0.55Sr0.45MnO3 layers across the La0.67Ca0.33MnO3 spacer up to room temperature, even above the Curie temperature of the La0.67Ca0.33MnO3 layers. However, magnetization versus temperature curves present signatures of the magnetic ordering of both compounds. No extrinsic magnetoresistance associated with the multilayered structure was observed in the whole temperature range due to the presence of the interlayer ferromagnetic coupling. (C) 2003 American Institute of Physics.
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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:000182789700049 Approved no
Call Number BT @ hernan @ Serial 169
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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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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 Sirena, M.; Zimmers, A; Haberkorn, N.; Kaul, E.E.; Steren, L.B.; Lesueur, J.; Wolf, T.; Le Gall, Y.; Grob, J.-J.; Faini, G.
Title Direct observation of electronic inhomogeneities induced by point defect disorder in manganite films Type Journal Article
Year 2010 Publication (up) Journal of Applied Physics Abbreviated Journal JAP
Volume 107 Issue Pages 113903
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Abstract
Address
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 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ ekaul @ Serial 633
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Author Guimpel, J.; Haberkorn, N.; Sirena, M.; Steren, L.B.; Saldarriaga, W.; Baca, E.; Gomez, M.E.
Title Interface effects in perovskite superlattices Type Journal Article
Year 2004 Publication (up) JOURNAL OF LOW TEMPERATURE PHYSICS Abbreviated Journal
Volume 135 Issue 1-2 Pages 115-118
Keywords
Abstract The effect of interface disorder in perovskite superlattices, either with the substrate or between layers dominates the physics of the material, even when the lattice parameter of the component materials differs in less than 1%. Unexpected behavior emerges, like exchange bias in a system where no antiferromagnetic material has been included in the superlattice design.
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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 0022-2291 ISBN Medium
Area Expedition Conference
Notes ISI:000189139000012 Approved no
Call Number BT @ hernan @ Serial 166
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Author Sirena, M.; Haberkorn, N.; Granada, M.; Steren, L.B.; Guimpel, J.
Title Oxygen and disorder effect in the magnetic properties of manganite films Type Journal Article
Year 2004 Publication (up) JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 272 Issue Pages 1171-1173
Keywords
Abstract We have made a systematic study of the magnetic properties of low doped manganite films submitted to different oxygenation treatments. We have found that oxygenation dynamics depends critically of the strain field in the sample. The T-C and the Mr increase as the oxygen content is increased. A decrease of the coercive field of the LSMO-STO films was observed, indicating that annealing treatments increase the oxygen content reducing oxygen vacancies. (C) 2004 Elsevier 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:000222236700179 Approved no
Call Number BT @ hernan @ Serial 162
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