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Author (down) 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
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Notes ISI:000171670100004 Approved no
Call Number BT @ hernan @ Serial 75
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Author (down) 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
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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 ISI:000222236700045 Approved no
Call Number BT @ hernan @ Serial 63
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Author (down) Sereni, J.G.; Trovarelli, O.; Schmerber, G.; Kappler, J.P.
Title Coexistence of magnetic order and heavy fermion behavior in Ce7X3 Type Journal Article
Year 1992 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 108 Issue 1-3 Pages 183-184
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Abstract Low temperature specific heat and magnetic susceptibility measurements on Ce7X3 (X = Rh, Ni) compounds are reported. Ce7Rh3 shows an onset of spontaneous magnetization at 7.2 K. About 40% of the expected R ln 2 entropy gain is found in the paramagnetic phase, related to a gamma(HT) = 1.1 J/K2 mol specific heat coefficient. In Ce7Ni3 an antiferromagnetic transition is observed at 1.7 K, superimposed to a large C(p)/T electronic contribution, described by a gamma(HT) = 0.9 J/K2 mol coefficient for T > 10 K. These results are interpreted in terms of the three different crystal sublattices of Ce. The entropy gain related to each transition allows to identify the behaviour of each sublattice. In the case of Ce7Ni3 one sublattice behaves as a heavy fermion system, with a value of C(p)/T = 3.3 J/K2 Ce at. Such a behaviour is confirmed under an applied magnetic field.
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Notes ISI:A1992HH32900075 Approved no
Call Number BT @ hernan @ Serial 113
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Author (down) Sereni, J.G.; Nieva, G.; Kappler, J.P.
Title ANOMALOUS CRYSTAL-FIELD EFFECTS IN THE SPECIFIC-HEAT OF CE-HEAVY FERMION COMPOUNDS Type Journal Article
Year 1987 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 63-64 Issue Pages 101-103
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Notes ISI:A1987G356900031 Approved no
Call Number BT @ hernan @ Serial 128
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Author (down) Sereni, J.G.; Nieva, G.; Huber, J.G.; Braun, E.; Oster, F.; Bruck, E.; Roden, B.; Wohlleben, D.
Title Evidence for 4f-instability of dilute terbium in thorium Type Journal Article
Year 1987 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 63-64 Issue Pages 597-599
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Abstract We have measured the specific heat of dilute Th1?xTbx alloys (0.44 < x < 2.15 a/o), which rises linearly between 0.4 and 0.9 K with a slope of ?C/T ? 450 mJ/K2molTb followed by a Schottky anomaly with a maximum near 3.8 K. The high temperature ??T product was found to be 4% lower than that of Tb3+. The resistivity shows no minimum at low temperatures. Discussion is made in terms of non-integral valence of Tb.
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Notes ISI:A1987G356900173 Approved no
Call Number BT @ hernan @ Serial 129
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Author (down) Sereni, J.G.; Kappler, J.P.
Title Magnetic and thermal properties of CeCu Type Journal Article
Year 1992 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 109 Issue 2-3 Pages 349-352
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Abstract Magnetic susceptibility, high field magnetization and specific heat measurements on CeCu are presented. An antiferromagnetic transition is observed at T(N) = 313 K, with some evidences of low dimensionality of the order parameter. The saturation magnetization. M(s) = 1.16-mu(B), implies that the crystalline electric field (CEF) ground state doublet is strongly magnetic, in agreement with the low temperature Curie constant C = 0.46 emu K/mol. In the high temperature limit (T > 50 K), the obtained Curie constant is C = 0.65 emu K/mol, which suggests an overall CEF splitting larger than 200 K. The entropy gain at the magnetic transition is 72% of the expected R in 2. The missing entropy is related to a specific heat anomaly with a maximum at approximately 13 K, which is attributed to magnetic fluctuations in the Ce chains. The transition temperature and the high temperature broad maximum in the specific heat are weakly affected by an applied magnetic field of 1 T.
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Notes ISI:A1992HP06000034 Approved no
Call Number BT @ hernan @ Serial 112
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Author (down) 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 ISI:A1985AKL5200061 Approved no
Call Number BT @ hernan @ Serial 131
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Author (down) Pureur, P.; Sereni, J.G.; Schaf, J.
Title Specific heat and magnetic susceptibility in YNd alloys Type Journal Article
Year 1992 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 104 Issue 3 Pages 1632-1634
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Abstract We report on the specific heat and dc magnetic susceptibility measurements of the YNd 4.5, 6.8 and 9.0 at % alloys. These systems present long-range SDW order just below the critical temperature. For temperatures well below T(C), the spin glass type of behavior is manifest. An interpretation is given in terms of a disorder- and frustration-induced breaking of the SDW coherence into small domains.
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Notes ISI:A1992HH32800067 Approved no
Call Number BT @ hernan @ Serial 115
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Author (down) Pureur, P.; Fraga, G. L.; Brandao, D. E.; Caudron,R.; Safa, H.; Nieva, G.
Title Specific heat measurements in scandium-rare earth anisotropic spin glasses Type Journal Article
Year 1987 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 68 Issue 2 Pages 213-217
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Abstract We report on specific heat measurements at low temperature of the anisotropic spin glass alloys ScDy 3 at%, ScEr 4.25 at% and ScEr 10 at%. We find that at the lowest temperature range the data indicate the occurrence of an anisotropy induced gap around zero frequency in the density of states of the magnetic excitations. Moreover, some of our specific heat curves present a maximum coinciding with Tg, raising thus the question of thermal signs for a spin glass phase transition in anisotropic systems.
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Notes Approved no
Call Number BT @ gnieva @ Serial 425
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Author (down) Kappler, J.P.; Schmerber, G.; Sereni, J.G.
Title Magnetic and thermal properties of Ce5Rh3 Type Journal Article
Year 1992 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 115 Issue 2-3 Pages 241-244
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Abstract Magnetic susceptibility, high field magnetization and specific heat measurements on Ce5Rh3 are reported. Two antiferromagnetic transitions are observed at T(N)=4.5 K and T(N)'=2.6 K. The magnetization curve at 1.5 K reveals a nontrivial magnetic structure in this compound, with a saturation magnetization of 0.72mu(B). The high temperature Curie constant (0.64 emu K/mol), the Curie-Weiss constant (THETA(p)=-45 K) and the entropy related with the magnetic transitions (DELTAS(m)=0.8 R In 2) indicate the presence of a Kondo-type component in the ground state of Ce5Rh3.
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Notes ISI:A1992JV02200022 Approved no
Call Number BT @ hernan @ Serial 111
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