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Author (up) 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 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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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 (up) 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 Journal of Magnetism and Magnetic Materials Abbreviated Journal Proceedings of the International Conference on Magnetism (ICM 2003)
Volume 272-276, Part 2 Issue Pages 1171-1173
Keywords Manganite fims; Oxigenation; Magnetic properties
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 TC 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.
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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 Approved no
Call Number BT @ jguimpel @ Serial 622
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Author (up) 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 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 (up) 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 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 (up) Sirena, M.; Steren, L.B.; Guimpel, J.
Title Magnetic relaxation in bulk and film manganite compounds Type Journal Article
Year 2001 Publication PHYSICAL REVIEW B Abbreviated Journal
Volume 64 Issue 10 Pages
Keywords
Abstract We have investigated the time dependence of the magnetic and transport properties of La0.6Sr0.4MnO3 films and bulk samples. A significant magnetic aftereffect has been observed in all the samples through magnetization and resistivity measurements. The relaxation effects can be described by the addition of a logarithmic to an exponential contribution. The weight of each contribution is strongly temperature dependent, with a relaxation that is predominantly logarithmic at low temperatures (T<30 K) and exponential at high temperatures (T>100 K). As the film thickness is decreased the magnetic relaxation becomes more important and the magnetic viscosity of the system increases. These results point out the important role of structural defects in the magnetic relaxation of the samples.
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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 0163-1829 ISBN Medium
Area Expedition Conference
Notes ISI:000170978400046 Approved no
Call Number BT @ hernan @ Serial 173
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Author (up) Sirena, M.; Steren, L.B.; Guimpel, J.
Title Magnetic after-effect in manganite films Type Journal Article
Year 2001 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 226 Issue Pages 847-848
Keywords
Abstract The time dependence of the magnetic and transport properties on La0.6Sr0.4MnO3 films and bulk samples has been studied through magnetization and resistivity measurements. A magnetic after-effect has been observed in all samples. At low temperatures, the low-field magnetization, can be described by the function M(t) = M-c + M-d exp(-t/tau) + S(H, T)ln(t), The resistivity increases logarithmically in the same temperature range. indicating the evolution of the sample to a more disordered state. Above a characteristic temperature, this behaviour is reversed and an increase of the magnetization with time is observed. The relaxation parameters depend on the bulk or films character of the samples. In the latter case, a dependence on the film thickness was found. A direct correlation between the time dependence of the resistivity and magnetization curves in manganite compounds was found. (C) 2001 Elsevier Science 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:000170708600308 Approved no
Call Number BT @ hernan @ Serial 174
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Author (up) 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 Journal of Applied Physics Abbreviated Journal JAP
Volume 107 Issue Pages 113903
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Abstract
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ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ ekaul @ Serial 633
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Author (up) Steren, L.B.; Sirena, M.; Guimpel, J.
Title Magnetic ordered phase in La0.6Sr0.4MnO3 ferromagnets Type Journal Article
Year 2002 Publication PHYSICAL REVIEW B Abbreviated Journal
Volume 65 Issue 9 Pages
Keywords
Abstract The ferromagnetic phase of La0.6Sr0.4MnO3 thin films has been investigated through measurements of magnetization loops at different temperatures, zero-field-cooled and field-cooled magnetization curves obtained under different magnetic fields. We have found that the main sources of the “bulk” coercivity in manganite films are the film/substrate interface and film surface. The temperature dependence of the coercivity is described by a “strong domain-wall pinning” model, independently of the thickness and substrate. The magnetization-vs-temperature curves, measured under different magnetic fields (10 Oe<H<2.5 kOe), have been explained in terms of the magnetic hysteresis of the films. We find no evidence of glass states or of the existence of single-domain clusters, as suggested by other authors.
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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 1098-0121 ISBN Medium
Area Expedition Conference
Notes ISI:000174547900096 Approved no
Call Number BT @ hernan @ Serial 172
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Author (up) Steren, L.B.; Sirena, M.; Guimpel, J.
Title Substrate effect on the magnetic behavior of manganite films Type Journal Article
Year 2000 Publication 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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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:000086728800281 Approved no
Call Number BT @ hernan @ Serial 178
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Author (up) Steren, L.B.; Sirena, M.; Guimpel, J.
Title Substrate influence on the magnetoresistance and magnetic order in La0.6Sr0.4MnO3 films Type Journal Article
Year 2000 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 211 Issue 1-3 Pages 28-34
Keywords
Abstract We report structural, magnetic and transport measurements on La0.6Sr0.4MnO3 thin films grown on MgO and TiSrO3 substrates with thickness varying from 5 to 500 nm. We find that the lattice mismatch between substrates and films affects the morphology and induced-strains of the films. We show that these two different effects strongly influence the ferromagnetic order, the metal-insulator transition, the localization of the current carriers and the magnetoresistance of these materials. (C) 2000 Elsevier Science 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:000085772100006 Approved no
Call Number BT @ hernan @ Serial 179
Permanent link to this record