| Records |
| Author |
Haberkorn, N.; Sirena, M.; Guimpel, J.; Steren, L.B. |
| Title |
Disorder influence on the magnetic properties of La0.55Sr0.45MnO3/SrTiO3 superlattices |
Type |
Journal Article |
| Year |
2004 |
Publication  |
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS |
Abbreviated Journal |
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| Volume |
272 |
Issue |
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Pages |
1244-1246 |
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| Abstract |
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 @ |
Serial |
163 |
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| Author |
Granada, M.; Maiorov, B.; Sirena, M.; Steren, L.B.; Guimpel, J. |
| Title |
Hall effect in La0.6Sr0.4MnO3 thin films |
Type |
Journal Article |
| Year |
2004 |
Publication |
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS |
Abbreviated Journal |
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| Volume |
272 |
Issue |
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Pages |
1836-1838 |
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| Abstract |
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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| Author |
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 |
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| Volume |
226 |
Issue |
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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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| Author |
Steren, L.B.; Sirena, M.; Guimpel, J. |
| Title |
Substrate influence on the magnetoresistance and magnetic order in La0.6Sr0.4MnO3 films |
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Journal Article |
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2000 |
Publication |
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS |
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211 |
Issue |
1-3 |
Pages |
28-34 |
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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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0304-8853 |
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ISI:000085772100006 |
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no |
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BT @ hernan @ |
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179 |
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Sirena, M.; Haberkorn, N.; Granada, M.; Steren, L.B.; Guimpel, J. |
| Title |
Oxygen and disorder effect in the magnetic properties of manganite films |
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Journal Article |
| Year |
2004 |
Publication |
Journal of Magnetism and Magnetic Materials |
Abbreviated Journal |
Proceedings of the International Conference on Magnetism (ICM 2003) |
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272-276, Part 2 |
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Pages |
1171-1173 |
| Keywords |
Manganite fims; Oxigenation; Magnetic properties |
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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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0304-8853 |
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no |
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BT @ jguimpel @ |
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622 |
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| Author |
Sirena, M.; Granada, M.; Steren, L.B.; Guimpel, J. |
| Title |
Metal/insulator manganite multilayers |
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Journal Article |
| Year |
2002 |
Publication |
PHYSICA B-CONDENSED MATTER |
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| Volume |
320 |
Issue |
1-4 |
Pages |
172-174 |
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We have studied the transport and magnetic properties of strongly textured metal/insulator La1-xSrxMnO3 (x = 0.4, 0.1) bilayers and trilayers, grown by DC magnetron sputtering over MgO and SrTiO3 substrates. The multilayers present transport properties similar to those of the La0.6Sr0.4MnO3 films, being very sensitive to deposition conditions. Magnetic multilayers show a metal-insulator transition around T-c (similar to250 K) and colossal magnetoresistance which is maximum around T-c. No extrinsic magnetoresistance associated with the multilayered structure was observed, probably due to the presence of ferromagnetic coupling between the metallic layers, as suggested by magnetization measurements. (C) 2002 Elsevier Science B.V. All rights reserved. |
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0921-4526 |
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ISI:000177607700047 |
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BT @ hernan @ |
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170 |
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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 |
Publication |
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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Causa, M.T.; Dutrus, S.M.; Fainstein, C.; Nieva, G.; Sanchez, R.; Steren, L.B.; Tovar, M.; Zysler, R.; Oseroff, S.B.; Vier, D.C.; Schultz, S.; Fisk, Z.; Smith, J.L. |
| Title |
Magnetic ordering in dilute GdxEu1−xBa2Cu3O7−δ superconductors |
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Journal Article |
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1988 |
Publication |
Physica C: Superconductivity |
Abbreviated Journal |
Physica C |
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153 |
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188-189 |
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We have measured the specific heat of GdxEu1−xBa2Cu3O7−δ (0 ≤ × ≤ 1). The data show a λ-type anomaly at high concentrations and a broad Schottky type anomaly at intermediate and low concentrations. We compare this behavior with theoretical predictions for a 2-dimensional Ising system. |
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BT @ gnieva @ |
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432 |
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Steren, L.B.; Sirena, M.; Guimpel, J. |
| Title |
Magnetic ordered phase in La0.6Sr0.4MnO3 ferromagnets |
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Journal Article |
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2002 |
Publication |
PHYSICAL REVIEW B |
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65 |
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9 |
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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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1098-0121 |
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ISI:000174547900096 |
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no |
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BT @ hernan @ |
Serial |
172 |
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Sirena, M.; Steren, L.B.; Guimpel, J. |
| Title |
Magnetic relaxation in bulk and film manganite compounds |
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Journal Article |
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2001 |
Publication |
PHYSICAL REVIEW B |
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64 |
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10 |
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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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0163-1829 |
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ISI:000170978400046 |
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no |
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BT @ hernan @ |
Serial |
173 |
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