Browsing by Author "Lora-Serrano, R"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Antiferromagnetic exchange weakening in the TbRhIn5 intermetallic system with Y-substitution
    (Elsevier, 2018-07-01) Amaral, RP; Lora-Serrano, R; Garcia, DJ; Iwamoto, WA; Betancourth, D; Cadogan, JM; Muñoz-Pérez, S; Avdeev, M; Cobas-Acosta, R; Bittar, EM; Duque, JGS; Pagliuso, PG
    We report measurements of the temperature dependent specific heat and magnetic susceptibility in single crystals of the series of intermetallic compounds Tb1−xYxRhIn5 (nominal concentrations x = 0.0, 0.15, 0.3, 0.4, 0.5, 0.7). A mean field approximation to simulate the macroscopic properties along the series has been used. Neutron diffraction data in powdered samples of Tb0.6Y0.4RhIn5 and Tb0.6La0.4RhIn5 reveal antiferromagnetic (AFM) propagation vector k→=[12012] with the magnetic moments oriented along the tetragonal c axis or canted from this axis, respectively for Y and La-substitutions. Considering both the simulations of the magnetic exchange and neutron diffraction data, we discuss the role of combined effects of crystalline electric field (CEF) perturbations and dilution in the evolution of magnetic properties with Y and La contents. In particular, we found negligible variations of the Bnm parameters along the Y series. The decrease of TN with x is fully dominated by magnetic dilution effects. © 2018 Elsevier Ltd.
  • Thumbnail Image
    Item
    Antiferromagnetism weakening with Y-substitution in the TbRhIn5 intermetallic system
    (arXivLabs, 2017-08-31) Amaral, RP; Lora-Serrano, R; Garcia, DJ; Betancourth, D; Cadogan, JM; Muñoz-Pérez, S; Cobas-Acosta, R; Avdeev, M; Bittar, EM; Duque, JGS; Pagliuso, PG
    We report measurements of the temperature dependence specific heat, magnetic susceptibility in single crystals of the series of intermetallic compounds Tb1−xYxRhIn5 (nominal concentrations x=0.15,0.30,0.40,0.50 and 0.70). A mean field approximation to simulate the macroscopic properties along the series has been used. Neutron diffraction data in powdered sample of nominal concentration Tb0.6Y0.4RhIn5 reveal AFM propagation vector k=[12 0 12] with the magnetic moments oriented close to the tetragonal \textit{c} axis. We discuss the role of combined effects of crystalline electric field (CEF) perturbations and dilution in the magnetic properties evolution with Y content. In particular, we suggest that changes in the Tb-In first neighbors distances, i.e. the TbIn3 cuboctahedra distortion, are responsible for changes in the Tb crystalline potential and the possible reorientation of Tb magnetic moments for x>0.4. This reflects non negligible variations of the Bmn crystal field parameters and the energy levels splitting with \textit{x}. CC BY: Creative Commons Attribution
  • Thumbnail Image
    Item
    Crystal field interactions in the chiral compounds RNi3Ga9 (R = Tb, Dy, Ho and Er) studied by inelastic neutron scattering
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Gil, L; Lora-Serrano, R; Duque, JGS; Garcia, DJ; Cadogan, S; Rule, KC
    In recent years, compounds with chiral structures have attracted much attention mainly because of noncollinear and non-coplanar spin textures, which have an important application in spintronics. In chiral compounds, the lack of inversion symmetry can give rise to an asymmetric spin interaction, the so-called Dzyaloshinskii-Moriya interaction, which contributes to the symmetric exchange interaction and anisotropy effects from the crystal field. These interactions’ coexistence can result in unusual magnetic properties and exotic magnetic structures with potential for many applications and novel phenomena. In this work, we study the magnetic properties of the chiral compounds RN i3Ga9 (R = Tb, Dy, Ho and Er), which crystalize in a trigonal ErNi3Al9-type structure with non-centrosymmetric space group R32 [1]. For this purpose, we analyzed the inelastic neutron scattering (INS) spectra in powder samples at several temperatures (T) to study the crystal electric field (CEF) excitations and ground-state. The INS experiments were performed at the SIKA beamline using the cold triple-axis spectrometer. The spectrum was analyzed at four temperatures for ErN i3Ga9 (T = 8, 20, 50 and 100K) and two temperatures for T bN i3Ga9 (T = 50 and 100K), HoN i3Ga9 (T = 30 and 100K) and DyN i3Ga9 (T = 50 and 100K). Moreover, transverse and longitudinal magnetic susceptibility was measured in single-crystalline samples to fit the CEF parameters better. We developed a code based on the magnetic susceptibility and differential cross-section for magnetic scattering at low Q (dipole approximation) to process and analyze the experimental data. The effective CEF hamiltonian for the system follows the C3 point symmetry, which results in 9 CEF parameters overall. The least-square fitting procedure uses a machine-learning algorithm based on particle swarm optimization. We report the energy levels scheme due to the crystal field and the CEF ground state’s eigenfunctions. In particular, the INS spectra for the ErNi3Ga9 compound showed peaks associated with the so-called hot transitions, which take place between excited energy levels. We only observed peaks associated with transitions between the ground-state and the first excited levels for R = Ho, Tb, and Dy. The calculated INS spectra and magnetic susceptibility were in good agreement with the experimental data. In particular, the calculated magnetic susceptibility showed that the direction of easy magnetization occurs along the c-axis for the ErNi3Ga9 compound and along the basal plane for the other compounds. It evidences the oblate and prolate nature of the rare-earth ions charge distributions. In summary, we used inelastic neutron scattering data to establish the CEF parameters for all compounds according to the C3 point symmetry. The obtained parameters describe the CEF energy levels’ configuration and the relative intensity of the peaks observed in the INS spectrum, besides the transverse and longitudinal magnetic susceptibility in the paramagnetic region.