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Author 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 (up) ISI:A1987G356900031 Approved no
Call Number BT @ hernan @ Serial 128
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Author 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 (up) ISI:A1987G356900173 Approved no
Call Number BT @ hernan @ Serial 129
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Author KAPPLER, J.P.; SCHMERBER, G.; SERENI, J.G.
Title CERIUM MAGNETIC-BEHAVIOR IN CE(PD,M) WITH M = CO, NI, RH, IR, PT, CU, AG AND AU Type Journal Article
Year 1988 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 76-7 Issue Pages 185-186
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Notes (up) ISI:A1988T046300057 Approved no
Call Number BT @ hernan @ Serial 124
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Author Fraga, G.L.F.; Brandao, D.E.; Sereni, J.G.
Title Specific heat of X2MnSn (X = Co, Ni, Pd, Cu), X2MnIn (X = Ni, Pd) and Ni2MnSb Heusler compounds Type Journal Article
Year 1991 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 102 Issue 1-2 Pages 199-207
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Abstract Results of low-temperature specific heat measurements (1.5-8.0 K) on X2MnSn (X = Co, Ni, Pd, Cu), X2Mnln (X = Ni, Pd) and Ni2MnSb Heusler compounds are presented. All the compounds, except the cobalt based one, exibit a lattice spectrum anomaly described by an Einstein's term (soft-phonons). For all but one compound, the experimental values of the electronic specific heat coefficients are, at least, twice as big as the theoretical estimates. For two compounds it was possible to determine the magnetic effective field on Mn nuclei.
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Notes (up) ISI:A1991GX03900034 Approved no
Call Number BT @ hernan @ Serial 117
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Author 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 (up) ISI:A1992HH32800067 Approved no
Call Number BT @ hernan @ Serial 115
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Author 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 (up) ISI:A1992HH32900075 Approved no
Call Number BT @ hernan @ Serial 113
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Author KAPPLER, J.P.; SCHMERBER, G.; TROVARELLI, O.; SERENI, J.G.
Title HEAVY FERMION AND INTERMEDIATE VALENCE BEHAVIOR IN CE24CO11 Type Journal Article
Year 1992 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 108 Issue 1-3 Pages 185-186
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Abstract Low temperature specific heat and magnetic susceptibility measurements on Ce24Co11 are reported. The electronic specific heat can be decomposed into two contributions: a low temperature one (arising at T < 5 K), with a maximum of 2.2 J/K mol at 0.9 K, and another one becoming dominant at T > 5 K, characterized by a gamma(HT) = 1.8 J/K2 mol efficient. The (chi)T product changes continuously with temperature, from 0.48 emu K/mol at 2 K to 7.85 emu K/mol at 200 K. Reminding that 1 mol = 1f.u. contains 24 Ce atoms distributed in ten unequivalent crystalline sites, we interpret the experimental results as due to: one atom which behaves as a heavy fermion, and the rest as intermediate valents, with a distribution of characteristic energies governed by nine different environments. The specific heat behaviour under applied field confirms this interpretation.
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Notes (up) ISI:A1992HH32900076 Approved no
Call Number BT @ hernan @ Serial 114
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Author 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 (up) ISI:A1992HP06000034 Approved no
Call Number BT @ hernan @ Serial 112
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Author 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 (up) ISI:A1992JV02200022 Approved no
Call Number BT @ hernan @ Serial 111
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Author SERENI, J.G.; TROVARELLI, O.
Title CORRELATION BETWEEN THE HYBRIDIZATION STRENGTH AND THE CE TO CE-LIGAND SPACING IN CET(2)X(2) COMPOUNDS Type Journal Article
Year 1995 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 140 Issue Pages 885-886
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Abstract The hybridization strength of the Ce-4f electrons with d or p orbitals of neighbouring sites, is analyzed through the comparison of the Ce-T and Ce-X spacings in CeT(2)X(2) compounds. Four different regimes, directly related to the increase of the hybridization strength, are recognized. This systematic indicates that the Ce behaviour depends more strongly on the overlap of f-p than of f-d orbitals.
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Notes (up) ISI:A1995QM07400073 Approved no
Call Number BT @ hernan @ Serial 100
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