| Records |
| Author |
Steren, L.B.; Sirena, M.; Guimpel, J. |
Title  |
Magnetic ordered phase in La0.6Sr0.4MnO3 ferromagnets |
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Journal Article |
| Year |
2002 |
Publication |
PHYSICAL REVIEW B |
Abbreviated Journal |
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| Volume |
65 |
Issue |
9 |
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| 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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| ISSN |
1098-0121 |
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ISI:000174547900096 |
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no |
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BT @ hernan @ |
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172 |
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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 |
JOURNAL OF APPLIED PHYSICS |
Abbreviated Journal |
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| Volume |
93 |
Issue |
10 |
Pages |
6177-6181 |
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| 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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0021-8979 |
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ISI:000182789700049 |
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BT @ hernan @ |
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169 |
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Sirena, M.; Steren, L.B.; Guimpel, J. |
| Title |
Magnetic after-effect in manganite films |
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Journal Article |
| Year |
2001 |
Publication |
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS |
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226 |
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Pages |
847-848 |
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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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0304-8853 |
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ISI:000170708600308 |
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BT @ hernan @ |
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174 |
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Guimpel, J.; Haberkorn, N.; Sirena, M.; Steren, L.B.; Saldarriaga, W.; Baca, E.; Gomez, M.E. |
| Title |
Interface effects in perovskite superlattices |
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Journal Article |
| Year |
2004 |
Publication |
JOURNAL OF LOW TEMPERATURE PHYSICS |
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| Volume |
135 |
Issue |
1-2 |
Pages |
115-118 |
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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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0022-2291 |
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ISI:000189139000012 |
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no |
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BT @ hernan @ |
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166 |
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Haberkorn, N.; Guimpel, J.; Sirena, M.; Steren, L.B.; Campillo, G.; Saldarriaga, W.; Gomez, M.E. |
| Title |
Interface disorder and transport properties in HTC/CMR superlattices |
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Journal Article |
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2004 |
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PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS |
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408 |
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896-897 |
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The physical properties of superlattices are affected by interface disorder, like roughness and interdiffusion. X-ray diffraction allows its measurement through modeling and structure refinement. The high-T-c RBa2Cu3O7 (RBCO) and colossal magneto resistance La(x)A(1-x)MnO(3) (LAMO) perovskites are interesting superlattice partners given their similar lattice parameters and because the combination of magnetic and superconducting properties is interesting for both basic and applied research. We have investigated the structural and transport properties of YBCO/La2/3Ca1/3MnO3 and GdBCO/La0.6Sr0.04MnO3 superlattices grown by sputtering on (100)MgO. We find a roughness of 1 RBCO unit cell and a 30% interdiffusion in the same length from the interfaces for all samples. The superconducting behavior is found strongly dependent on the LAMO layer thickness. (C) 2004 Elsevier B.V. All rights reserved. |
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0921-4534 |
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ISI:000224051700375 |
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no |
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BT @ hernan @ |
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160 |
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Granada, M.; Maiorov, B.; Sirena, M.; Steren, L.B.; Guimpel, J. |
| Title |
Hall effect in La0.6Sr0.4MnO3 thin films |
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Journal Article |
| Year |
2004 |
Publication |
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS |
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272 |
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1836-1838 |
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We studied the temperature and thickness dependence of the transport properties of La0.6Sr0.4MnO3 films. Hall voltage and magnetoresistance measurements on 10 and 150 nm thick films were performed with this porpose. From the ordinary Hall component, we calculated the density of carriers, which has hole-character and is systematically lower than that expected from the chemical composition of the manganite in both samples. Localization effects observed at low temperature in the resistivity of the thinner film, associated with the substrate-induced disorder, are correlated with a decrease of the density of carriers. (C) 2003 Elsevier B.V. All rights reserved. |
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0304-8853 |
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ISI:000222236800084 |
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no |
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BT @ hernan @ |
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164 |
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Haberkorn, N.; Sirena, M.; Guimpel, J.; Steren, L.B. |
| Title |
Disorder influence on the magnetic properties of La0.55Sr0.45MnO3/SrTiO3 superlattices |
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Journal Article |
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2004 |
Publication |
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS |
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272 |
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1244-1246 |
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The structural and physical properties of La0.55Sr0.45MnO3/SrTiO3 superlattices grown by magnetron sputtering are studied. Two deposition temperatures and different mismatched substrates and buffer layers were used. The structure was determined by refinement through X-ray diffraction pattern fitting. The results indicate 1 unit cell (u.c.) interdiffusion at the interfaces and a 1 u.c. layer thickness fluctuation, i.e. roughness. In-plane hysteresis loops show the expected ferromagnetic behavior, while the perpendicular-to-plane hysteresis loops show anomalies which could evidence magnetic domain size inhomogeneities and stress. (C) 2004 Elsevier B.V. All rights reserved. |
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0304-8853 |
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ISI:000222236700212 |
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no |
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BT @ hernan @ |
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163 |
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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 |
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Journal Article |
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2010 |
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Journal of Applied Physics |
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JAP |
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107 |
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113903 |
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BT @ ekaul @ |
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633 |
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Sirena, M.; Haberkorn, N.; Granada, M.; Steren, L.B.; Guimpel, J. |
| Title |
Correlation between structure and magnetic properties of manganite-based multilayers |
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Journal Article |
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2003 |
Publication |
JOURNAL OF APPLIED PHYSICS |
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93 |
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10 |
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7244-7246 |
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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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0021-8979 |
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ISI:000182822300273 |
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BT @ hernan @ |
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168 |
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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 |
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Journal Article |
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2004 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
Appl. Phys. Lett. |
| Volume |
84 |
Issue |
19 |
Pages |
3927-3929 |
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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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0003-6951 |
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ISI:000221210100069 |
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BT @ hernan @ |
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165 |
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