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Author Carreras Oropesa, W.G.; Encina, S.; Pedrazzini, P.; Correa, V.F.; Sereni, J.G.; Vildosola, V.; García D.J.; Cornaglia, P.S.
Title Minimal model for the magnetic phase diagram of CeTi1-xScxGe, GdFe1-xCoxSi, and related materials Type Journal Article
Year 2020 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal
Volume (down) 503 Issue Pages 166614
Keywords Magnetism; RTX
Abstract We present a theoretical analysis of the magnetic phase diagram of CeTi1-xScxGe and GdFe1-xCoxSi as a function

of the temperature and the Sc and Co concentration x, respectively. CeScGe and GdCoSi, as many other RTX

(R=rare earth, T=transition metal, X=p-block element) compounds, present a tetragonal crystal structure

where bilayers of R are separated by layers of T and X. While GdFeSi and CeTi0.75Sc0.25Ge are ferromagnetic,

CeScGe and GdCoSi order antiferromagnetically with the R 4f magnetic moments on the same bilayer aligned

ferromagnetically and magnetic moments in nearest neighbouring bilayers aligned antiferromagnetically. The

antiferromagnetic transition temperature TN decreases with decreasing concentration x in both compounds and

for low enough values of x the compounds show a ferromagnetic behavior. Based on these observations we

construct a simplified model Hamiltonian that we solve numerically for the specific heat and the magnetization.

We find a good qualitative agreement between the model and the experimental data. Our results show that the

main magnetic effect of the Sc→Ti and Co→Fe substitution in these compounds is consistent with a change in

the sign of the exchange coupling between magnetic moments in neighbouring bilayers. We expect a similar

phenomenology for other magnetic RTX compounds with the same type of crystal structure.
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Notes Approved no
Call Number BT @ victor.correa @ Serial 856
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Author Facio, J.I.; Betancourth, D.; Cejas Bolecek, N.R.; Jorge, G.A.; Pedrazzini, P.; Correa, V.F.; Cornaglia, P.S.; Vildosola, V.; García D.J.
Title Lattice specific heat for the RMIn5 (R=Gd, La,Y; M=Co, Rh) compounds: Non-magnetic contribution subtraction Type Journal Article
Year 2016 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume (down) 407 Issue Pages 406-4011
Keywords
Abstract
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Notes Approved no
Call Number BT @ victor.correa @ Serial 730
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Author Betancourth, D.; Facio, J.I.; Pedrazzini, P.; Jesus, C.B.R.; Pagliuso, P.G.; Vildosola, V.; Cornaglia, P.S.; García, D. J.; Correa, V. F.
Title Low Temperature magnetic properties of GdCoIn5 Type Journal Article
Year 2015 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume (down) 374 Issue Pages 744-747
Keywords
Abstract A comprehensive experimental and theoretical study of the low temperature properties of GdCoIn5 was performed. Specific heat, thermal expansion, magnetization and electrical resistivity were measured in good quality single crystals down to 4He temperatures. All the experiments show a second-order-like phase transition at 30 K probably associated with the onset of antiferromagnetic order. The magnetic susceptibility shows a pronounced anisotropy below T N with an easy magnetic axis perpendicular to the crystallographic ĉ-axis. Total energy GGA+U calculations indicate a ground state with magnetic moments localized at the Gd ions and allowed a determination of the Gd-Gd magnetic interactions. Band structure calculations of the electron and phonon contributions to the specific heat together with Quantum Monte Carlo calculations of the magnetic contributions show a very good agreement with the experimental data. Comparison between experiment and calculations suggests a significant anharmonic contribution to the specific heat at high temperature (View the MathML sourceT≳100K).
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Call Number BT @ victor.correa @ Serial 701
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Author Franco, D.G.; Carbonio, R.E.; Kaul, E.E.; Nieva, G.
Title Tailoring the ground state of the ferrimagnet La2Ni(Ni1/3Sb2/3)O6 Type Journal Article
Year 2013 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume (down) 346 Issue Pages 196-202
Keywords Ferrimagnetic; Double perovskite; Magnetic frustration; Superexchange and super-superexchange interaction; Magnetic oxide
Abstract We report on the magnetic and structural properties of La2Ni(Ni1/3Sb2/3)O6 in polycrystal, single crystal and thin film samples. We found that this material is a ferrimagnet ( T c ≈ 100 K ) which possesses a very distinctive and uncommon feature in its virgin curve of the hysteresis loops. We observe that bellow 20 K it lies outside the hysteresis cycle, and this feature was found to be an indication of a microscopically irreversible process possibly involving the interplay of competing antiferromagnetic interactions that hinder the initial movement of domain walls. This initial magnetic state is overcome by applying a temperature dependent characteristic field. Above this field, an isothermal magnetic demagnetization of the samples yield a ground state different from the initial thermally demagnetized one.
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ISSN 0304-8853 ISBN Medium
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Notes Approved no
Call Number BT @ pedrazp @ Serial 666
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Author Antonio, D.; Dolz, M.I.; Pastoriza, H.
Title Magnetization measurement of single La0.67Ca0.33MnO3 nanotubes in perpendicular magnetic fields using a micromechanical torsional oscillator Type Journal Article
Year 2010 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal
Volume (down) 322 Issue 5 Pages 488-493
Keywords Manganite nanotubes; Micromachined magnetometers; Shape anisotropy
Abstract Using a silicon micromechanical resonator as a sensitive magnetometer, the authors have studied both experimentally and theoretically the magnetic behavior of two isolated ferromagnetic nanotubes of perovskite La0.67Ca0.33MnO3. The article investigates the specific configuration where a magnetic field H is applied perpendicular to the magnetic easy axis of an isolated nanotube characterized by an uniaxial anisotropy constant K. In this situation, the magnetization M reduces the effective elastic constant kM of the resonator. This softening of the mechanical system is opposed to the hardening effect of M observed in a previous work, where H was applied parallel to the easy axis. Moreover, in this magnetic field configuration two distinct magnetization regimes are manifested, depending on the magnitude of H. For H[not double greater-than sign]2K/M the magnetization is almost parallel to the applied magnetic field and for H[double less-than sign]2K/M it is almost parallel to the easy axis of the nanotube. At a certain value of H there is a sharp transition
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ISSN 0304-8853 ISBN Medium
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Notes Approved no
Call Number BT @ hernan @ 13272 Serial 585
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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 (down) 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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ISSN 0304-8853 ISBN Medium
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Notes ISI:000264170500007 Approved no
Call Number BT @ hernan @ Serial 194
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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 (down) 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
Area Expedition Conference
Notes ISI:000254416300060 Approved no
Call Number BT @ hernan @ Serial 49
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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 (down) 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 ISI:000247666000326 Approved no
Call Number BT @ hernan @ Serial 51
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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 (down) 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 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 (down) 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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Language Summary Language Original Title
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ISSN 0304-8853 ISBN Medium
Area Expedition Conference
Notes ISI:000222236700179 Approved no
Call Number BT @ hernan @ Serial 162
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