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Author Bauer, E.; Galatanu, A.; Rogl, P.; Berisso, M.G.; Pedrazzini, P.; Sereni, J.G.
Title Loss of magnetism in CePd2-xNixAl3 Type Journal Article
Year (up) 2002 Publication PHYSICA B-CONDENSED MATTER Abbreviated Journal
Volume 312 Issue Pages 464-465
Keywords
Abstract Hexagonal CePd2-xNixAl3 exhibits a crossover from a Kondo lattice showing magnetic order at T(N)similar or equal to2.8 K for xless than or equal to0.2 to intermediate valence (IV) for x-->2. Though T-N(x) is weakly affected upon Pd/Ni substitution before vanishing at finite temperature, the Kondo temperature T-K progressively increases. Above xsimilar or equal to0.3 the phase boundary no longer exists and strong spin fluctuations cause pronounced deviations from a Fermi-liquid ground state before the IV regime is established for xgreater than or equal to1. (C) 2002 Elsevier Science B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526 ISBN Medium
Area Expedition Conference
Notes ISI:000175871000171 Approved no
Call Number BT @ hernan @ Serial 296
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Author Pedrazzini, P.
Title Estudio comparativo de inestabilidades magneticas en compuestos de cerio Type Book Whole
Year (up) 2003 Publication Abbreviated Journal
Volume Issue Pages 116
Keywords
Abstract La variedad de nuevos estados y fenómenos físicos descubiertos en compuestos intermetálicos que contienen tierras raras o actínidos ha motivado, durante las últimas cuatro décadas, el estudio sostenido de sus diagramas de fases magnéticas. El interés actual se centra en el estudio de la región del diagrama de fases en la que se desestabiliza el orden magnético en sistemas en base a cerio, yterbio y uranio. En dicha región se han detectado, por ejemplo, superconductividad no convencional y el comportamiento denominado “non-Fermi liquid” (NFL), caracterizado por dependencias anómalas de las propiedades térmicas, magnéticas y de transporte a muy bajas temperaturas.Un esquema sencillo, el denominado “diagrama de Doniach”, ha guiado la interpretación de la desestabilización del orden magnético de los sistemas antes mencionados. Sin embargo, la mayoría de los sistemas estudiados no pueden ser descriptos por dicho esquema, lo que ha motivado el desarrollo de una clasificación fenomenológica de los diagramas de fases que ha sido aplicada fundamentalmente a compuestos en base a cerio. Dicha clasificación define tres tipos de diagramas de fase que pueden distinguirse a través de la forma en que el orden magnético es suprimido al variar un parámetro de control (por ejemplo, concentración o presión), acercándose a su valor crítico. Dentro de este contexto, presentamos el estudio de la supresión del orden antiferromagnético de los compuestos intermetálicos CeIn3, CeRh2Si2 y CePd2Al3 cuando se alean los ligantes del Ce. Los sistemas resultantes, CeIn3−xSnx, Ce(CuxRh1−x)2Si2 y CePd2−xNixAl 3, presentan diferentes estructuras cristalinas y los efectos producidos por la aleación son distintos en cada uno de los casos. Sus diagramas de fases magnéticas son analizados y comparados con la clasificación fenomenológica antes mencionada, por lo que se investiga en más detalle la región en la que se produce la inestabilidad magnética, en las cercanías de las respectivas concentraciones críticas. A partir de nuestros resultados y de lo reportado en la literatura, discutimos la mencionada clasificación fenomenológica. Los principales resultados de este trabajo están asociados al diagrama de fases complejo del sistema cúbico CeIn3−xSnx, en el que la temperatura de orden antiferromagnético (AF), TN(x), puede ser detectada en más de un orden y medio de magnitud en temperatura. Alrededor de la concentración crítica xc #approx =# 0,65 en que TN #-># 0 se observa comportamiento del tipo NFL. En el caso del sistema Ce(CuxRh1−x)2Si2, la relevancia de este estudio se basa en la comparación con el sistema isoestructural Ce(PdzRh1−z)2Si2, que permite descartar un rol fundamental de la anisotropía en la supresión del orden magnético AF del compuesto CeRh2Si2 (anómalo, pues TN = 36 K). Finalmente, el estudio del CePd2−xNixAl_3 revela un diagrama de fases complejo que puede estar asociado al desorden producido al alear, y en el que también se observa comportamiento del tipo NFL. El estudio conjunto de los sistemas mencionados permite postular escenarios en los que variables adicionales, que no son tenidas en cuenta por el esquema de Doniach, conducen a los distintos comportamientos observados.
Address Instituto Balseiro – CNEA y UNCuyo, 8400 S.C. de Bariloche
Corporate Author Thesis Ph.D. thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ hernan @ Serial 335
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Author Custers, J.; Cichorek, T.; Gegenwart, P.; Caroca-Canales, N.; Stockert, O.; Geibel, C.; Steglich, F.; Pedrazzini, P.; Sereni, J.G.
Title Non-Fermi liquid effects close to a QCP in CeIn3-xSnx Type Journal Article
Year (up) 2003 Publication ACTA PHYSICA POLONICA B Abbreviated Journal
Volume 34 Issue 2 Pages 379-382
Keywords
Abstract Resistivity and specific heat measurements at low temperatures on CeIn3-xSnx samples with concentrations x = 0.6, 0.65 and 0.7 demonstrate that with increasing Sn-alloying, the antiferromagnetic ordering temperature decreases continuously down to T = 0 K and disappears at a quantum critical point. We observe non-Fermi liquid (NFL) behavior in the resistivity and the specific heat, however the temperature dependencies are different from the predictions for a spin density wave (SDW) scenario. The resistivity at the critical point shows e.g., a linear temperature dependence, as expected for two dimensional fluctuations, which however can be excluded in the cubic structure of CeIn3-xSnx.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0587-4254 ISBN Medium
Area Expedition Conference
Notes ISI:000181544200015 Approved no
Call Number BT @ hernan @ Serial 68
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Author Pedrazzini, P.; Berisso, M.G.; Sereni, J.G.; Caroca-Canales, N.; Deppe, M.; Geibel, C.
Title Complex magnetic phase diagram near the quantum critical point in CeIn3-xSnx Type Journal Article
Year (up) 2003 Publication ACTA PHYSICA POLONICA B Abbreviated Journal
Volume 34 Issue 2 Pages 363-366
Keywords
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.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0587-4254 ISBN Medium
Area Expedition Conference
Notes ISI:000181544200011 Approved no
Call Number BT @ hernan @ Serial 292
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Author Tovar, M.; Sereni, J.G.; Pedrazzini, P.; Caneiro, A.; Prado, F.; Butera, A.; Causa, M.T.
Title Magnetization and specific heat of La doped Sr2FeMoO6 Type Journal Article
Year (up) 2004 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal J. Magn. Magn. Mater.
Volume 272 Issue Pages 857-858
Keywords
Abstract We present high-temperature magnetization and low-temperature specific heat measurements performed on the electron doped double perovskite Sr1.7La0.3FeMoO6. We have obtained the electronic contribution to C-p, gamma = 11.5(5) mJ/mol K-2. The electronic susceptibility, derived from the magnetic measurements in the paramagnetic regime (T > T-c = 390K), was chi(e)(0) =(4.9 +/- 1.5) x 10(-4) emu/mol. Anti ferromagnetic coupling between localized and itinerant moments was inferred from the data, with a coupling constant lambda = -(475 +/- 50)mol/emu, that results in a ferromagnetic-like Curie-Weiss susceptibility with Theta = 390(5) K. These results are compared with those obtained for the undoped material. (C) 2003 Published by Elsevier B.V.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-8853 ISBN Medium
Area Expedition Conference
Notes ISI:000222236700045 Approved no
Call Number BT @ hernan @ Serial 63
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Author Pedrazzini, P.; Berisso, M.G.; Trovarelli, O.; Sereni, J.G.; Geibel, C.
Title Evolution of the ground state in the ternary system CeT2Si2 (T=Cu, Rh and Pd) Type Journal Article
Year (up) 2004 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 135 Issue 1-2 Pages 143-146
Keywords
Abstract The heavy fermion compounds CeCu2Si2, CeRh2Si2 and CePd2Si2 have been intensively investigated due to the non-conventional relation between superconductivity and magnetism. We have studied these compounds as constituents of a ternary system, where the Ce(RhxCu1-x)(2)Si-2, Ce(PdyRh1-y)(2)Si-2 and Ce(CuzPd1-z)(2)Si-2 alloys span the sides of a triangle with the respective stoichometric compounds at each vertex. In this article we discuss the evolution of the ground state throughout this ternary system, and we analyse (by means of the electrical resistivity) the influence of doping-induced disorder on the Kondo and magnetic ordering temperatures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2291 ISBN Medium
Area Expedition Conference
Notes ISI:000189139000019 Approved no
Call Number BT @ hernan @ Serial 66
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Author Pedrazzini, P.; Berisso, M.G.; Caroca-Canales, N.; Deppe, M.; Geibel, C.; Sereni, J.G.
Title Low temperature magnetic phase diagram of the cubic non-Fermi liquid system Celn(3-x)Sn(x) Type Journal Article
Year (up) 2004 Publication The European Physical Journal B – Condensed Matter Abbreviated Journal Eur. Phys. J. B
Volume 38 Issue 3 Pages 445-450
Keywords
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.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6028 ISBN Medium
Area Expedition Conference
Notes ISI:000222309400006 Approved no
Call Number BT @ hernan @ Serial 289
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Author Deppe, M.; Pedrazzini, P.; Caroca-Canales, N.; Gelbel, C.; Sereni, J.G.
Title Investigations of CePd1-xRhx single crystals located near a ferromagnetic quantum critical point Type Journal Article
Year (up) 2006 Publication PHYSICA B-CONDENSED MATTER Abbreviated Journal
Volume 378-380 Issue Pages 96-97
Keywords
Abstract Investigations of CePd1-xRhx polycrystals have revealed a continuous transition from a ferromagnetic state at x = 0 to an intermediate valence state at x = 1 and evidenced non-Fermi liquid behavior near the critical concentration x(c) approximate to 0.85 where T-C is continuously suppressed to T = 0 K. We present here first results of specific heat and magnetization measurements on CePd1-xRhx single crystals with composition close to the critical point. They confirm the results obtained on polycrystals and reveal a rather low magnetic anisotropy, despite the orthorhombic structure. (c) 2006 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526 ISBN Medium
Area Expedition Conference
Notes ISI:000238426600033 Approved no
Call Number BT @ hernan @ Serial 56
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Author Sereni, J.G.; Pedrazzini, P.; Bauer, E.; Galatanu, A.; Aoki, Y.; Sato, H.
Title Detailed study of the CePd2-xNixAl3 magnetic phase diagram around its critical concentration Type Journal Article
Year (up) 2006 Publication Journal of Physics: Condensed Matter Abbreviated Journal J. Phys.: Cond. Matter
Volume 18 Issue 15 Pages 3789-3802
Keywords
Abstract Thermal, magnetic and transport measurements on CePd2-xNixAl3 alloys within the 0 <= x <= 1 range are reported, including applied pressure (p) and magnetic field on some selected samples. The low temperature results indicate that long range antiferromagnetic order is robust up to x = 0.2, whereas between 0.25 and 0.5 magnetic fluctuations give rise to non-Fermiliquid (NFL) behaviour. In this critical region, the low temperature specific heat can be described as due to two components, the major showing a NFL C-p/T = gamma(0) – gamma(1) root T dependence, while the minor one includes a decreasing fraction of short range order degrees of freedom. The latter is only observed close to the critical point, x(cr) approximate to 0.35. Electrical resistivity (rho) studies performed under pressure for x = 0.5 allow us to investigate the evolution of the NFL state around and beyond x(cr), where the exponent of rho proportional to T-n increases from n = 1 (for p = 0) up to n = 2 (for p = 12 kbar). This exponent is also observed at normal pressure on the x = 1.0 sample. indicating the onset of the Fermi liquid behaviour. Doping and pressure effects are compared by fitting high temperature resistivity data employing a unique function which allows us to describe the evolution of the characteristic energy of this series along a large range of concentration and pressure.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984 ISBN Medium
Area Expedition Conference
Notes ISI:000237410400027 Approved no
Call Number BT @ hernan @ Serial 58
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Author Pedrazzini, P.; Jaccard, D.; Lapertot, G.; Flouquet, J.; Inada, Y.; Kohara, H.; Onuki, Y.
Title Probing the extended non-Fermi liquid regimes of MnSi and Fe Type Journal Article
Year (up) 2006 Publication Physica B – Condensed Matter Abbreviated Journal Physica B
Volume 378-380 Issue Pages 165-166
Keywords electrical resistivity; Fermi liquid; ferromagnetic materials; high-pressure effects; iron; magnetic superconductors; manganese alloys; silicon alloys; strongly correlated electron systems; superconducting transition temperature; superconducting transitions; whiskers; MnSi; Fe
Abstract Recent studies show that the non-Fermi liquid (NFL) behavior of MnSi and Fe spans over an unexpectedly broad pressure range, between the critical pressure p and around 2p. In order to determine the extension of their NFL regions, we analyze the evolution of the resistivity ρ(T)˜A(p)T at higher pressures. We find that in MnSi the n=32 exponent holds below 4.8GPa≈3p, but it increases above that pressure. At 7.2 GPa we observe the low-temperature Fermi liquid exponent n=2 whereas for T>1.5K, n=53. Our measurements in Fe show that the NFL behavior ρ˜T extends at least up to 30.5 GPa, above the entire superconducting (SC) region. In the studied pressure range, the onset of the SC transition reduces by a factor 10 down to Tconset(30.5GPa)=0.23K, while the A—coefficient diminishes monotonically by around 50%.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 469
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