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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
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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ISSN 0304-8853 ISBN Medium
Area Expedition Conference
Notes (up) ISI:000170708600308 Approved no
Call Number BT @ hernan @ Serial 174
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Author Vildosola, V.L.; Llois, A.M.; Weissmann, M.; Sereni, J.G.
Title Magnetic behaviour of Ce(Pd1-xMx) compounds (M = Rh, Ni and Ag) within the LDA approximation Type Journal Article
Year 2001 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 236 Issue 1-2 Pages 6-8
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Abstract Ce intermetallic compounds have been intensively studied in the last few decades due to the large variety of behaviours they exhibit. In particular, two ways of demagnetizing Ce have been experimentally tried within the ferromagnetic systems Ce(Pd1-xMx), namely through electronic concentration variations (M=Rh) and volume reductions (M=Ni). On the other hand, when Pd is substituted by Ag, a transformation from a ferromagnetic to an antiferromagnetic ground state has been observed. In this work, we analyse the evolution of the magnetism of Ce in the above-mentioned family of compounds by calculating the spin contribution to magnetism that results from spin polarised LDA calculations. (C) 2001 Elsevier Science B.V. All rights reserved.
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ISSN 0304-8853 ISBN Medium
Area Expedition Conference
Notes (up) ISI:000171670100004 Approved no
Call Number BT @ hernan @ Serial 75
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Author Tovar, M.; Sereni, J.G.; Pedrazzini, P.; Caneiro, A.; Prado, F.; Butera, A.; Causa, M.T.
Title Magnetization and specific heat of La doped Sr2FeMoO6 Type Journal Article
Year 2004 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal J. Magn. Magn. Mater.
Volume 272 Issue Pages 857-858
Keywords
Abstract We present high-temperature magnetization and low-temperature specific heat measurements performed on the electron doped double perovskite Sr1.7La0.3FeMoO6. We have obtained the electronic contribution to C-p, gamma = 11.5(5) mJ/mol K-2. The electronic susceptibility, derived from the magnetic measurements in the paramagnetic regime (T > T-c = 390K), was chi(e)(0) =(4.9 +/- 1.5) x 10(-4) emu/mol. Anti ferromagnetic coupling between localized and itinerant moments was inferred from the data, with a coupling constant lambda = -(475 +/- 50)mol/emu, that results in a ferromagnetic-like Curie-Weiss susceptibility with Theta = 390(5) K. These results are compared with those obtained for the undoped material. (C) 2003 Published by Elsevier B.V.
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ISSN 0304-8853 ISBN Medium
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Notes (up) ISI:000222236700045 Approved no
Call Number BT @ hernan @ Serial 63
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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 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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ISSN 0304-8853 ISBN Medium
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Notes (up) ISI:000222236700179 Approved no
Call Number BT @ hernan @ Serial 162
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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
Volume 272 Issue Pages 1244-1246
Keywords
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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ISSN 0304-8853 ISBN Medium
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Notes (up) ISI:000222236700212 Approved no
Call Number 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
Volume 272 Issue Pages 1836-1838
Keywords
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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ISSN 0304-8853 ISBN Medium
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Notes (up) ISI:000222236800084 Approved no
Call Number BT @ hernan @ Serial 164
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Author Sereni, J.G.; Caroca-Canales, N.; Geibel, C.
Title Ferromagnetic instability at the edge of intermediate valence Type Journal Article
Year 2007 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 310 Issue 2 Pages E214-E216
Keywords
Abstract Preliminary study of structural, thermal and magnetic properties on ferromagnetic CePt1-yRhy (0.40 <= y <= 1) is presented. Like in the recently studied CePd1-xRhx, this new system undergoes a quantum critical behavior between the ferromagnetic CePt (T-C = 6K) and unstable valence CeRh. Regardless the electronic and atomic size similarities between Pt and Pd atoms, signi. cant differences in their respective phase diagrams are observed around the critical points. While CePd1-xRhx shows an asymptopic T-C(x) decrease indicating a smeared quantum phase transition, in CePt1-yRhyTC(y) vanishes beyond y = 0.80 after a plateau starting at y = 0.60 at T-C approximate to 1.8K. Peculiarities of this critical region are compared with other Ce-systems. (c) 2006 Elsevier B.V. All rights reserved.
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ISSN 0304-8853 ISBN Medium
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Notes (up) ISI:000247666000326 Approved no
Call Number BT @ hernan @ Serial 51
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Author Braghta, A.; Schmerber, G.; Derory, A.; Sereni, J.G.; Kappler, J.P.
Title Magnetic and thermal properties of Ce2Pd2Sn Type Journal Article
Year 2008 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 320 Issue 6 Pages 1141-1145
Keywords
Abstract X-ray diffraction, susceptibility and specific heat studies on ternary Ce2Pd2Sn intermetallic compound and on its isostructural nonmagnetic compound La2Pd2Sn are reported. On Ce2Pd2Sn in absence of magnetic field, we confirm the existence of two magnetic transitions at T-N = 4.8K (antiferromagnetic transition) and T-C = 2.2K (ferromagnetic transition) and the specific heat results, measured down to 0.5 K, allow to recognize the transition at 2.2K as a first-order transition. A description based on molecular field calculations for the S = 1/2 resonant level model leads to a characteristic Kondo T-K of about 3K. (C) 2007 Elsevier B.V. All rights reserved.
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ISSN 0304-8853 ISBN Medium
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Notes (up) ISI:000254416300060 Approved no
Call Number BT @ hernan @ Serial 49
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Author Haberkorn, N.; Larregola, S.; Franco, D.; Nieva, G.
Title Inhomogeneous ferrimagnetic-like behavior in Gd2/3Ca1/3MnO3 single crystals Type Journal Article
Year 2009 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 321 Issue 9 Pages 1133-1136
Keywords
Abstract We present a study of the magnetic properties of Gd2/3Ca1/3MnO3 single crystals at low temperatures, showing that this material behaves as an inhomogeneous ferrimagnet. In addition to small saturation magnetization at 5 K, we have found history dependent effects in the magnetization and the presence of exchange bias. These features are compatible with microscopic phase separation in the clean Gd2/3Ca1/3MnO3 system studied. (C) 2008 Elsevier B.V. All rights reserved.
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Notes (up) ISI:000264170500007 Approved no
Call Number BT @ hernan @ Serial 194
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Author SERENI, J.G.
Title The role of “p-like” orbitals in Ce valence instabilities Type Journal Article
Year 1985 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 47-48 Issue FEB Pages 228-230
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Abstract From the analysis of spectroscopical data of atomic Ce, the [f(dsp)] configuration is found to be the least energetic when the metallization enthalpy is taken into account. The p-character of the band in Ce IV compounds is discussed and the p-f hybridization proposed.
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Notes (up) ISI:A1985AKL5200061 Approved no
Call Number BT @ hernan @ Serial 131
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