Kappler, J. P., P. Haen, O. Trovarelli, J. G. Sereni, and M. J. Besnus. "Low temperature properties of Ce(Pd1-xAgx)." Zeitschrift für Physik B Condensed Matter 101, no. 1 (1996): 29–34.
Abstract: Low temperature magnetic, transport and thermal measurements on the Ce(Pd1-xAgx) system, with x ranging from 0 to 0.17, are presented. The magnetic structure of the ordered phase transforms from ferromagnetic to antiferromagnetic with only 2at.% Pd substitution, whereas reentrance of ferromagnetism is observed at 15at.% Ag content. We propose the break in the periodicity of the Coulomb potential (Pd is a hole-like atom, whereas Ag is an electron-like one) as the dominant effect for such a change in the magnetic behavior of this system.
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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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Kneidinger, F., I. Zeiringer, A. Siderenko, E. Bauer, H. Michor, P. Rogl, and J. G. Sereni. "Physical properties of CeIrSi with trillium-lattice frustrated magnetism." Physical Review B 100, no. 13 (2019): 134442.
Abstract: Magnetic (χ), transport (Ï), and heat capacity (Cm) properties of CeIrSi are investigated to elucidate the effect of geometric frustration in this compound with trillium type structure because, notwithstanding its robust effective moment,
μeff≈2.46μB, this Ce-lattice compound does not undergo a magnetic transition. In spite of that it shows broad Cm(T)/T and χ(T) maxima centered at Tmax≈1.5 K, while a ÏâˆT2 thermal dependence, characteristic of electronic spin coherentfluctuations,is observed below Tcoh≈2.5 K. Magnetic field does not affect significantly the position of the mentioned maxima up to ≈1 T, though χ(T) shows an incipient structure that completely vanishes at
μ0H≈1 T. Concerning the ÏâˆT2 dependence, it is practically not affected by magneticfield up to μ0H=9 T, with the residual resistivity Ï0(H) slightlydecreasing and Tcoh(H) increasing. These results are compared with thephysical properties observed in other frustrated intermetallic compound.
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Kuchler, R., P. Gegenwart, J. Custers, O. Stockert, N. Caroca-Canales, C. Geibel, J. G. Sereni, and F. Steglich. "Quantum criticality in the cubic heavy-fermion system CeIn3-xSnx." Physical Review Letters 96, no. 25 (2006): 256403.
Abstract: We report a comprehensive study of CeIn3-xSnx (0.55 <= x <= 0.8) single crystals close to the antiferromagnetic quantum-critical point (QCP) at x(c)approximate to 0.67 by means of the low-temperature thermal expansion and Gruneisen parameter. This system represents the first example for a cubic heavy fermion in which T-N can be suppressed continuously down to T=0. A characteristic sign change of the Gruneisen parameter between the antiferromagnetic and paramagnetic states indicates the accumulation of entropy close to the QCP. The observed quantum-critical behavior is compatible with the predictions of the itinerant theory for three-dimensional critical spin fluctuations. This has important implications for the role of the dimensionality in heavy-fermion QCPs.
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Lobos, A. M., A. A. Aligia, and J. G. Sereni. "Specific heat of magnetic Ce alloys within a two-component model." European Physical Journal B 41, no. 3 (2004): 289–294.
Abstract: We propose a description of the electronic properties of Ce alloys as an inhomogeneous mixture of two components: one containing magnetic Ce ions with an RKKY interaction J(H) between them, and the other described as a collection of Kondo impurities with exchange interaction J(K). Both J(H) and J(K) are assumed to depend on a composition parameter X, with a Gaussian distribution around a value X-0 (near to the expectation value of X), related to the experimental composition parameter x of the alloy. When the concentration of the Kondo impurities is large, the specific heat C displays non-Fermi liquid behavior over a wide temperature range. The main qualitative features of C/T as a function of temperature T observed in several Ce alloys are reproduced using simple J(H)(X) and J(K)(X) dependences.
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Luengo, C. A., J. M. Cotignola, J. G. Sereni, A. R. Sweedler, and M. B. Maple. "Heat capacity of ThU alloys at low temperatures." In Proceedings of the 13th International Conference on Low Temperature Physics (LT-13), edited by K. D. Timmerhaus, W. J. O'Sullivan and E. F. Hammel, 585. Vol. 2. New York: Plenum Publishing Corp., 1974.
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