1,721,028 research outputs found
Physical properties of the magnetically frustrated very-heavy-fermion compound YbCu<sub>4</sub>Ni
No full textThe physical properties of the very-heavy-fermion compound YbCu4Ni were characterized through structural, magnetic, thermal, and transport studies along nearly four decades of temperature ranging between 50 mK and 300 K. At high temperature, the crystal electric field level splitting was determined with Δ1(Γ6)=85K and Δ2(Γ8)≈200K, the latter being a quartet in this cubic symmetry. An effective magnetic moment μeff≈3μB is evaluated for the Γ7 ground state, while at high temperature the value for a Yb3+ ion is observed. At low temperature this compound shows the typical behavior of a magnetically frustrated system undergoing a change of regime at a characteristic temperature T∗≈200mK into of Fermi-liquid-type "plateau" of the specific heat: Cm/T|T→0 = const. The change in the temperature dependence of the specific heat coincides with a maximum and a discontinuity in respective inductive and dissipative components of the ac susceptibility. More details about the nature of this ground state are revealed by the specific heat behavior under applied magnetic field.Fil: Sereni, Julian Gustavo Renzo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Curlík, I.. University of Prešov; EslovaquiaFil: Giovannini, M.. Università degli Studi di Genova; ItaliaFil: Strydom, A.. University of Johannesbur; SudáfricaFil: Reiffers, M.. Max Planck Institute for Chemical Physics of Solids; Alemania. University of Prešov; Eslovaqui
Phase relations at 600 °C in ytterbium-palladium-indium system
No full textThe isothermal section of the ytterbium-palladium-indium phase diagram was constructed at 600 °C in the Pd < 60 at% region, as a result of X-ray powder diffraction and scanning electron microscopy with energy dispersive X-ray analysis. The existence of a new ternary compound Yb5Pd2In was observed at this temperature, and its crystal structure was determined (structure type Mo5SiB2, space group I4/mcm, a =0.78820(2) nm, c = 1.41596(5) nm). Magnetic and thermodynamic properties of two ternary compositions YbPdIn4 and Yb17Pd50In33 were also investigated. Yb17Pd50In33 presents a stable trivalent Yb3+, whereas in YbPdIn4 the Yb ion is in a nearly divalent state
Evidence for magnetic dimers and skyrmion lattice formation in Eu2Pd2Sn
No full textThe magnetic, thermal, and transport properties of the noncentrosymmetric compound Eu2Pd2Sn are reexamined
with the inclusion of detailed measurements. In its paramagnetic phase, the outstanding feature of
this compound is the formation of Eu2+ dimers, which allows us to understand the deviation of the magnetic
susceptibility χ(T ) from the Curie-Weiss law below about 70 K, the field-dependent magnetization M(B) below
≈80K, and the reduced entropy at the ordering temperature S(TN ) = 0.64R ln(8). A significant change in the
exchange interactions occurs between T ≈ 70K (where θP = 18K) and TN = 13.3K (to θP = −4.5K). The
strong electronic overlap, arising from the reduced Eu-Eu spacing (compared with that in pure Eu2+) is expected
to favor dimer quasiparticles formation, leading to a significant change in the magnetic structure. From the
analysis of the derivatives of the magnetic parameters, ∂χ/∂T and ∂M/∂B, as well as the field dependence of
the specific heat and mangnetoresistance, a comprehensive magnetic phase diagram is obtained. Two critical
points are recognized and a tentative description of the magnetic structures is proposed. The possible formation
of a skyrmion lattice, arising from the presence of magnetically frustrated pockets in the phase diagram, is
suggested by theoretical studies on hexagonal structures that exhibit similar interaction patterns
Phase equilibria and crystal structures in the ytterbium–copper–zinc system
No full textPhase equilibria in the isothermal section (600 °C) of the ytterbium-copper-zinc ternary system were determined over the entire concentration range by powder X-ray diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Extended substitutional Cu/Zn homogeneity regions are mainly formed from the Yb-Zn and Yb-Cu binary compounds. There are four ternary compounds, namely τ1-YbCu5−xZnx (cubic AuBe5 type, 0.7 < x ≤ 1.5), τ2-YbCu5−xZnx (hexagonal CaCu5 type, 1.8 ≤ x ≤ 4.4), τ3-Yb2CuZn7 and τ4-Yb5Cu2−xZn1+x. Magnetic measurements were performed for compositions along the phases τ1-YbCu5−xZnx and τ2-YbCu5−xZnx, as well as for the compound Yb33Cu50Zn17 belonging to the pseudobinary system YbCu2-YbZn2. While the Yb ion has a valence of 2 + for compositions ≥33% at% Yb, the Yb valence along the YbCu5−xZnx composition line is influenced by the crystal structure: Yb3+ for the cubic AuBe5 type and nonmagnetic Yb2+ for the hexagonal CaCu5 type
YbPd2In: A promising candidate for strong entropy accumulation at very low temperature
No full textWe report on synthesis, crystal structure, magnetic, thermodynamic, and transport properties of the compound YbPd2In, crystallizing as a Heusler structure type. A trivalent state of the rare earth was determined by fitting the magnetic susceptibility with a Curie-Weiss law. This compound is characterized by showing very weak magnetic interactions and a negligible Kondo effect. A specific-heat jump was observed at T≈250mK, followed at higher temperature by a power-law decrease of CP(T)/T. The resulting large electronic entropy increase at very low temperature is rapidly shifted to higher temperature by the application of magnetic field. This magnetocaloric effect places YbPd2In as a very good candidate for adiabatic demagnetization cooling processes.Fil: Gastaldo, F.. Università degli Studi di Genova; ItaliaFil: Gabáni, S.. Institute of Experimental Physics; EslovaquiaFil: Džubinská, A.. Šafárik University; EslovaquiaFil: Reiffers, M.. University of Prešov; EslovaquiaFil: Pristáš, G.. Institute of Experimental Physics; EslovaquiaFil: Curlík, Ivan. University of Prešov; EslovaquiaFil: Skyba, P.. Institute of Experimental Physics; EslovaquiaFil: Clovecko, M.. Institute of Experimental Physics; EslovaquiaFil: Vavrek, F.. Institute of Experimental Physics; EslovaquiaFil: Sereni, Julian Gustavo Renzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Giovannini, M.. Università degli Studi di Genova; Itali
Evolution of the ground state of Yb ion in YbCu5-xSnx
No full textStructural and magnetic studies have been carried out for the cubic YbCu5-xSnx system of the MgCu4Sn-type, which exists in the solubility range 0.2 ≤ x ≤ 0.7. The magnetic properties of this system were compared with those of the analogous system YbCu5-xInx (0.1 ≤ x ≤ 1.0). These two systems appear to share the same scenario of evolution from a localized trivalent state of the Yb atom for low values of x(x = 0.2) to valence transition state in a wide temperature range (T ∼ 40–80 K) for intermediate values of x(x = 0.6, 0.7). Specific heat measurements performed for one of these compositions, YbCu4.4Sn0.6, show an increase at low temperatures T < 7 K most probably due to the presence of a high density of magnetic excitations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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