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Braghta, A., G. Schmerber, A. Derory, J. G. Sereni, and J. P. Kappler. "Magnetic and thermal properties of Ce2Pd2Sn." Journal of Magnetism and Magnetic Materials 320, no. 6 (2008): 1141–1145.
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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Gomez Berisso, M., J. G. Sereni, A. Braghta, G. Schmerber, B. Chevalier, and J. P. Kappler. "Field suppression of the modulated phase of Ce2Pd2Sn." Physica B 404, no. 19 (2009): 2930–2933.
Abstract: Low temperature magnetic (M) and thermal (CP) properties of the intermetallic compound Ce2Pd2Sn have been investigated at zero and different magnetic fields. Two transitions were recognized at and , with latter nearly coinciding with the extrapolated Curie-Weiss temperature . The Curie factor evaluated from T>=TM, is [approximate]2μB. The positive value of θP, the triangular coordination of the magnetic (Ce) atoms and the weak effect of applied magnetic field, reveal that TM cannot be considered as a canonic antiferromagnetic transition like claimed in the literature. M(T) measurements under moderate magnetic fields () show TC(B) increasing while TM(B) is practically not affected. Both transition merge in a critical point at for , where the intermediate phase is suppressed. At , the cusp of a first order transition is observed in CP(T). According to the proposed ferromagnetic ground state, it is followed by a CP(T)[is proportional to]T3/2exp(-Eg/T) dependence, with a gap of anisotropy .
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Kappler, J. P., P. Lehmann, G. Schmerber, G. Nieva, and J. G. Sereni. "Magnetic properties of the Ce-Rh binary phases." Journal de Physique Colloques 49, no. C8 (1988): 721–722.
Abstract: Crystallographic, magnetic and resistivity studies on the Ce-Rh binary phases clearly define two Ce ground state regions : i) CeRh3, CeRh2 and CeRh as intermediate valence compounds and ii) Ce5Rh4, Ce3Rh2 Ce5Rh3 and Ce7Rh3 with magnetic transitions at low temperature.
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Kappler, J. P., G. Schmerber, and J. G. Sereni. "Magnetic and thermal properties of Ce5Rh3." Journal of Magnetism and Magnetic Materials 115, no. 2-3 (1992): 241–244.
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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KAPPLER, J. P., G. SCHMERBER, and J. G. SERENI. "CERIUM MAGNETIC-BEHAVIOR IN CE(PD,M) WITH M = CO, NI, RH, IR, PT, CU, AG AND AU." Journal of Magnetism and Magnetic Materials 76-7 (1988): 185–186.
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KAPPLER, J. P., G. SCHMERBER, O. TROVARELLI, and J. G. SERENI. "HEAVY FERMION AND INTERMEDIATE VALENCE BEHAVIOR IN CE24CO11." JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 108, no. 1-3 (1992): 185–186.
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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KAPPLER, J. P., G. SCHMERBER, O. TROVARELLI, and J. G. SERENI. "COEXISTENCE OF HEAVY FERMION AND INTERMEDIATE VALENCE BEHAVIOR IN CE24CO11." Zeitschrift für Physik B Condensed Matter 86, no. 2 (1992): 253–256.
Abstract: Low temperature specific heat, magnetic susceptibility and L(III)-XAS 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/Kmole at 0.9 K, and another one becoming dominant at T > 5 K, characterized by a gamma(HT) = 1.8 J/K2mole coefficient. The chi.T product changes continuously with temperature, from 0.48 emu K/mole at 2 K to 7.85 emu K/mole at 200 K. The L(III)-mean valence is upsilon = 3.15. As the 24 Ce atoms are 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 Kondo and Intermediate Valent, with a distribution of characteristic energies governed by nine different environments. Qualitatively, the specific heat behaviour under applied field and the upsilon = 3.15 value are in agreement with this interpretation.
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NIEVA, G. L., J. G. SERENI, M. AFYOUNI, G. SCHMERBER, and J. P. KAPPLER. "FROM FERROMAGNETIC TO NON-MAGNETIC SINGLET GROUND-STATE IN CEPD1-XNIX." Zeitschrift für Physik B Condensed Matter 70, no. 2 (1988): 181–186.
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Pedrazzini, P., G. Schmerber, M. G. Berisso, J. P. Kappler, and J. G. Sereni. "Magnetic and superconducting properties of A(7)B(3) compounds (A = Th or La and B=Ni, Co, Fe or Pd, Rh, Ru)." PHYSICA C 336, no. 1-2 (2000): 10–18.
Abstract: High-temperature magnetization, low temperature specific heat, and ac-susceptibility measurements on Th7X3 (X = Ni, Co, and Fe) and La(7)Z(3) (Z = Pd, Rh, and Ru) superconductors are presented. The magnetic behaviour of the Th7X3 group has the characteristics of Pauli paramagnets. The La(7)Z(3) group also shows Pauli paramagnetism for Z = Pd and Ru, and signs of spin fluctuations for La7Rh3. Specific heat (C-p) measurements indicate a conventional BCS behaviour for La7Pd3 and La7Rh3, like that of the previously measured Th7X3 superconductors. in the case of La7Ru3, the reduced specific heat jump at the transition, the anomalous temperature dependence of C-p under magnetic field and a large upper critical field slope are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.
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Sereni, J. G., G. L. Nieva, G. Schmerber, and J. P. Kappler. "EVIDENCES FOR UNCONVENTIONAL SUPERCONDUCTIVITY IN RARE-EARTH INTERMETALLICS." Modern Physics Letters B 3, no. 16 (1989): 1225–1231.
Abstract: The specific heat of CeRu2 and La5Rh4 of the superconducting state does not follow a BCS-exponential temperature dependence, but a T2 law. At very low temperature (T = 0.1 Tc), CeRu2 shows a linear T dependence, which corresponds to a constant density of states. The experimental results are well described by the theoretical predictions for an axial state (CeRu2) and polar state (La5Rh4) superconductors. The small Sommerfeld coefficient of La5Rh4(? = 3.4 mJ/K2 La at.) excludes this compound from the heavy fermion superconductors.
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