Luengo, C. A., J. G. Huber, J. G. Sereni, A. R. Sweedler, J. M. Cotignola, and M. B. Maple. "Low temperature specific heat of ThU." Solid State Communications 10, no. 5 (1972): 459.
Abstract: The low temperature specific heat of the weakly magnetic system Image U has been measured in both the normal and superconducting states. U impurities are found to enhanve the normal state electronic specific heat coefficient γ at an unusually large rate of 4.85 ± 0.50 mJ/mole °K2 at. % U. The specific heat jump at the superconducting transition for an alloy of composition 0.075 at. % U follows the BCS law of corresponding states suggesting that the system Image U is essentially non-magnetic at superconducting temperatures.
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Martinelli, A., M. Giovannini, J. G. Sereni, and C. Ritter. "Suppression of ferromagnetic order by Ag-doping: a neutron scattering investigation on Ce2(Pd1−x Ag x )2In (x  =  0.20, 0.50)." Journal of Physics: Condensed Matter 30, no. 26 (2018): 265601.
Abstract: The ground state magnetic behaviour of Ce2(Pd0.8Ag0.2)2In and Ce2(Pd0.5Ag0.5)2In, found in the ferromagnetic branch of Ce2Pd2In, has been investigated by neutron powder diffraction at low temperature. Ce2(Pd0.8Ag0.2)2In is characterized by a ferromagnetic structure with the Ce moments aligned along the c-axis and values of 0.96(2) µB. The compound retains the P4/mbm throughout the magnetic transition, although the magnetic ordering is accompanied by a significant decrease of the lattice strain along [0 0 l], suggesting a magnetostructural contribution. The magnetic behaviour of Ce2(Pd0.5Ag0.5)2In is very different; this compound exhibits an extremely reduced magnetic scattering contribution in the diffraction pattern, that can be ascribed to a different kind of ferromagnetic ordering, with extremely reduced magnetic moments (~0.1 µ
B) aligned along [0 l 0]. These results point to a competition between different types of magnetic correlations induced by Ag-substitution, giving rise to a magnetically frustrated scenario in Ce2(Pd0.5Ag0.5)2In.
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Michor, H., J. G. Sereni, M. Giovannini, E. Kampert, L. Salamakha, G. Hilscher, and E. Bauer. "Elucidating the lack of magnetic order in the heavy-fermion CeCu2Mg." Physical Review B 95, no. 11 (2017): 115146.
Abstract: Magnetic, transport, and thermal properties of CeCu2Mg are investigated to elucidate the lack of magnetic order in this heavy-fermion compound with a specific heat value, Cmag/T|T→0≈1.2 J/mol K2 and robust effective magnetic moments (μeff≈2.46μB). The lack of magnetic order is attributed to magnetic frustration favored by the hexagonal configuration of the Ce sublattice. In fact, the effect of magnetic field on Cmag/T and residual resistivity Ï0 does not correspond to that of a Fermi liquid (FL) because a broad anomaly appears at Tmax≈1.2 K in Cmag(T)/T, without changing its position up to μ0H=7.5 T. However, the flattening of Cmag/T|T→0 and its magnetic susceptibility χT→0, together with the T2 dependence of Ï(T), reveal a FL behavior for T≤2 K which is also supported by Wilson and Kadowaki-Woods ratios. The unusual coexistence of FL and frustration phenomena can be understood by placing paramagnetic CeCu2Mg in an intermediate section of a frustration-Kondo model. The entropy, Smag, reaches 0.87Rln6 at T≃100 K, with a tendency to approach the expected value Smag=Rln6 of the J=5/2 ground state of Ce3+.
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Nöllmann, M., D. Shalom, P. Etchegoin, and J. G. Sereni. "Photobleaching and reorientational dynamics of dyes in a nematic liquid crystal." Physical Review E 59 (1999): 1850.
Abstract: The polarized fluorescence of excited dyes in a prototype nematic liquid crystal is studied as a function of temperature, polarization of the light, and laser wavelength. We show explicitly the coexistence of photobleaching and dye diffusion through the nematic host as two mechanisms influencing the magnitude of the fluorescence signal. In addition, we exhibit clear evidence of the presence of a torque at low input laser powers that twist the dye molecules with respect to the director orientation of the liquid crystal, if the dyes are resonantly excited. The fluorescence emission in this latter case is able to perceive the birefringence of the nematic liquid crystal host, and this is shown as clear oscillations in the polarized fluorescence as a function of temperature. Extensive qualitative comparisons of the experimental results with the mean-field Maier-Saupe theory of the nematic state are presented, and a model is proposed to account for the observations.
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Nieva, G., J. G. Sereni, and J. P. Kappler. "Thermal and magnetic anomalous crystal field effects in Ce-heavy fermion compounds." Physica Scripta 35, no. 2 (1987): 201–203.
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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., M. G. Berisso, N. Caroca-Canales, M. Deppe, C. Geibel, and J. G. Sereni. "Low temperature magnetic phase diagram of the cubic non-Fermi liquid system Celn(3-x)Sn(x)." The European Physical Journal B – Condensed Matter 38, no. 3 (2004): 445–450.
Abstract: In this paper we report a comprehensive study of the magnetic susceptibility (x), resistivity (p), and specific heat (C-P), down to 0.5 K of the cubic CeIn3-xSnx alloy. The ground state of this system evolves from antiferromagnetic (AF) in CeIn3 (T-N = 10.2 K) to intermediate-valent in CeSn3, and represents the first example of a Ce-lattice cubic non-Fermi liquid (NFL) system where T-N(x) can be traced down to T = 0 over more than a decade of temperature. Our results indicate that the disappearance of the AF state occurs near x(c) approximate to 0.7, although already at x approximate to 0.4 significant modifications of the magnetic ground state are observed. Between these concentrations, clear NFL signatures are observed, such as rho(T) approximate to rho(0) + A T-n (with n < 1.5) and C-P(T) proportional to -T ln(T) dependencies. Within the ordered phase a first order phase transition occurs for 0.25 < x < 0.5. With larger Sn doping, different weak rho(T) dependencies are observed at low temperatures between x = 1 and x = 3 while C-P/T shows only a weak temperature dependence.
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Pedrazzini, P., M. G. Berisso, N. Caroca-Canales, M. Deppe, C. Geibel, and J. G. Sereni. "Non-Fermi liquid behaviour in cubic CeIn3-xSnx." PHYSICA B-CONDENSED MATTER 312 (2002): 406–407.
Abstract: The alloy between the antiferromagnetic (AF) CeIn3 and the mixed valent CeSn3 is particularly interesting since it is one of the few cases where a magnetic to non-magnetic transition is observed in a cubic system. Although the resulting alloy CeIn3-xSnx has been investigated for over 20 years, no information is available about thermodynamic and transport properties below 2K. We report first measurements on resistivity rho(T) and specific heat C-P(T) down to 0.45 K. These results confirm the disappearance of the AF state near xcongruent to0.6. In samples close to this critical concentration, we observe a strong departure from the Fermi liquid behaviour, i.e. rho(T) approximate to rho(0) + a T-n (n < 1.5) and a logarithmic temperature dependence C-P(T)infinity – T ln (T), in more than a decade above the lowest investigated temperature. (C) 2002 Elsevier Science B.V. All rights reserved.
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Pedrazzini, P., M. G. Berisso, J. G. Sereni, N. Caroca-Canales, M. Deppe, and C. Geibel. "Complex magnetic phase diagram near the quantum critical point in CeIn3-xSnx." ACTA PHYSICA POLONICA B 34, no. 2 (2003): 363–366.
Abstract: A recent reinvestigation of the alloy system CeIn3-xSnx between the antiferromagnetic (AF) Kondo-lattice CeIn3 and the intermediate valent CeSn3 has shown that the AF order disappears at a quantum critical point (QCP) at x(c) approximate to 0.65. Preliminary evidences for a first order transition below T-N at x < x(c), indicating a complex magnetic phase diagram, have motivated the present detailed investigation of specific heat and resistivity on fine tuned samples in the 0.25 less than or equal to x less than or equal to x(c) range. These results confirm the first order transition at T-I < T-N in a reduced concentration range (0.25 < x < 0.47) and suggest that the phase boundary T-I (x) merge with the T-N(x) near x approximate to 0.37, leading to a tetracritical point. A similar first order transition was previously observed in the CeCu2(Si,Ge)(2) system at low Ge-concentration. Since in this alloy the first order transition also appears in the vicinity of a QCP, the question arises concerning how general this property is at AF critical points in Ce-based alloy systems.
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Pedrazzini, P., M. G. Berisso, J. G. Sereni, O. Trovarelli, and C. Geibel. "Magnetic phase diagram of Ce(CuxRh1-x)(2) Si-2." JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 226 (2001): 161–163.
Abstract: Magnetic, thermal and transport measurements on Ce(CuxRh1-x)(2)Si-2 are presented, The obtained phase diagram shows a rapid decrease of the magnetic order on the Rh rich-side. as determined by magnetic susceptibility measurements, followed by a region without magnetic order for x > 0.2. In this region, the electronic specific heat coefficient increases moderately up to 0.2J/mol K-2 for x = 0.8. evaluated at 0.5 K. Around 5 K a small anomaly is observed in the 0.8. As a function of doping, a maximum develops below 10 K in the electrical resistance. specific heat for 0.4 less than or equal to x less than or equal to 0.8. As a function of doping, a maximum develops below 10 K in the electru=ical resistance. Particularly, at x = 0.8, the temperature of the maximum of the electrical resistance slope coincides with the anomaly observed in the specific heat. (C) 2001 Elsevier Science B.V. All rights reserved.
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