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Berisso, M. G., P. Pedrazzini, J. G. Sereni, O. Trovarelli, C. Geibel, and F. Steglich. "Study of Ce(Rh1-xPdx)(2)Si-2: pronounced differences between the CeRh2Si2 and CePd2Si2 ground states." EUROPEAN PHYSICAL JOURNAL B 30, no. 3 (2002): 343–349.
Abstract: We present electrical resistivity and specific heat measurements of alloys on the Rh rich side of the phase diagram of the Ce(Rh1-xPdx)(2)Si-2 system. We compare these results with those obtained at intermediate and low Rh concentrations. The analysis of the concentration and temperature dependence of the entropy and of the scaling behaviour of C-et(T) and rho(T) clearly confirm a separation of the magnetic phase diagram into two regions: the region x less than or equal to 0.3, showing a concentration independent characteristic temperature for the 4f-electrons with T-0 approximate to 45 K, while for x > 0.3, T-0 decreases to T-0(x = 1) approximate to 15 K. At low Pd-content, T-N decreases very rapidly from T-N = 36 K in pure CeRh2Si2 to T-N = 18 K at x = 0.1. With higher Pd concentration T-N stabilizes at T-N approximate to 15 K whereas the magnitude of the anomalies in C-et(T) and in the susceptibility around T-N are further reduced and disappear at x approximate to 0.3. This differs from the behavior found on the Pd-rich side, where T-N decreases continuously to zero with increasing Rh content. The pronounced differences observed between both phase boundaries and the drastic effect of doping on the Rh rich side suggest an itinerant character in CeRh2 Si-2, in contrast with the localized character of CePd2Si2. Further evidence for the itinerant character of CeRh2Si2 is given by the rho(T) dependence observed for x less than or equal to 0.3, which scales with rho(T) of the prototype itinerant compound YCo2.
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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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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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Shalóm, D. E., S. Reparáz, and H. Pastoriza. "Finite Josephson junction arrays with open boundaries in magnetic field: Ground state energy and first critical field." The European Physical Journal B – Condensed Matter 40 (2004): 409–413.
Abstract: We have investigated the size dependence of the ground state energy as a function of the magnetic field in Josephson junction arrays with open boundaries. We present a simple rings model that reproduces with great confidence the size and field dependence of the energy of the system obtained by numerical simulation of the Hamiltonian. From these results we obtained the size dependence of the first penetration field, where the one-vortex state becomes favorable compared to the zero-vortex state.
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