DEPARTAMENTO MATERIA CONDENSADA

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https://nuclea.cnea.gob.ar/handle/20.500.12553/5228

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Examinando DEPARTAMENTO MATERIA CONDENSADA por Autor "Aligia, A.A."

Mostrando 1 - 2 de 2
  • Miniatura
    ÍtemAcceso Abierto
    Interpretation of experimental results on Kondo systems with crystal field
    (IOP Publishing, 2014-00-00) Romero, M.A.; Aligia, A.A.; Sereni, J.G.; Nieva, G.; Gerencia Física. Departamento Materia Condensada. División Bajas Temperaturas
    We present a simple approach to calculate the thermodynamic properties of single Kondo impurities including orbital degeneracy and crystal field effects (CFE) by extending a previous proposal by Schotte and Schotte (1975 Phys. Lett. 55A 38). Comparison with exact solutions for the specific heat of a quartet ground state split into two doublets shows deviations below 10% in the absence of CFE and a quantitative agreement for moderate or large CFE. As an application, we fit the measured specific heat of the compounds CeCu2Ge2, CePd3Si0.3, CePdAl, CePt, Yb2Pd2Sn and YbCo2Zn20. The agreement between theory and experiment is very good or excellent depending on the compound, except at very low temperatures due to the presence of magnetic correlations (not accounted for in the model).
  • Miniatura
    ÍtemAcceso Abierto
    Magnetostriction reveals orthorhombic distortion in tetragonal Gd compounds
    (American Physical Society, 2019-04-00) Betancourth, D.; Correa, V. F.; Facio, J.I.; Fernández J.; Vildosola, V.; Lora-Serrano, R.; Cadogan, J.M.; Aligia, A.A.; Cornaglia, P.S.; García D.J.; Gerencia Física. Departamento Materia Condensada. División Bajas Temperaturas
    We report detailed thermal expansion and magnetostriction experiments on GdCoIn5 and GdRh(In1−xCdx)5 (x=0 and 0.025) single-crystal samples that show a sudden change in the dilation at a field B★ for temperatures below the Néel transition temperature TN. We present a first-principles model including crystal-field effects, dipolar and exchange interactions, and the dependence of the latter with lattice distortions in order to fully account for the magnetostriction and magnetic susceptibility data. The mean-field solution of the model shows that a transition between metastable states occurs at the field B★. It also indicates that two degenerate phases should coexist at temperatures below TN, which may explain the lack of observation, in high-resolution x-ray experiments, of an orthorhombic distortion at the Néel transition, even though the experimentally determined magnetic structure breaks the tetragonal symmetry and the magnetoelastic coupling from our model is significant. These conclusions could be extended to other tetragonal Gd-based compounds that present the same phenomenology.