Browsing by Author "Muñoz-Pérez, S"
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- ItemAntiferromagnetic 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, PGWe 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.
- ItemAntiferromagnetism 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, PGWe 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
- ItemMagnetic order and spin-reorientation in HoGa(IOP Publishing, 2012-01-01) Susilo, RA; Muñoz-Pérez, S; Cobas, R; Cadogan, JM; Avdeev, MWe have determined the magnetic structure of the intermetallic compound HoGa by high-resolution neutron powder diffraction. This compound crystallizes in the orthorhombic (Cmcm) CrB-type structure and the magnetic structure comprises ferromagnetic order of the Ho sublattice along the c-axis. The Curie temperature is 66(3) K. Upon cooling below 20 K, the Ho magnetic moments cant away from the c-axis towards the ab-plane. At 3 K, the Ho moment is 8.8(2) μB and the Ho magnetic moments point in the direction θ = 30(2)° and phgr = 49(4)° with respect to the crystallographic c-axis. The observation of an ab-plane component at around 50° from the a-axis is in contrast with the suggested magnetic structure of ac order (θ = 32° and phgr = 0°) reported by Delyagin et al. [1] on the basis of a 119Sn Mössbauer spectroscopy study of a Sn-doped HoGa sample. However, we find that these two sets of orientations are in fact indistinguishable by Mössbauer spectroscopy. © Copyright 2021 IOP Publishing
- ItemMagnetic order and spin-reorientations in RGa (R = Dy, Ho and Er) intermetallic compounds(Australian Institute of Physics, 2013-02-06) Susilo, RA; Cadogan, JM; Ryan, DH; Lee-Horne, NR; Cobas, R; Muñoz-Pérez, S; Rosendahl-Hansen, B; Avdeev, MNot available
- ItemMagnetic order and structural properties of Tb2Fe2Si2C(Elsevier, 2016-01-05) Susilo, RA; Cadogan, JM; Hutchison, WD; Avdeev, M; Cobas, R; Muñoz-Pérez, S; Campbell, SJThe structural and magnetic properties of Tb2Fe2Si2C have been investigated by bulk measurements (magnetisation and specific heat), X-ray diffraction, neutron powder diffraction and 57Fe Mössbauer spectroscopy over the temperature range 3 K–300 K Tb2Fe2Si2C is antiferromagnetic with a Néel temperature TN of 44(2) K. The magnetic structure can be described with a propagation vector k = [0 0 ] with the Tb magnetic moments ordering along the b-axis. We also observed strong magnetoelastic effects in particular along the a- and c-axes associated with the antiferromagnetic transition. The 57Fe Mössbauer spectra show no evidence of magnetic splitting down to 10 K, indicating that the Fe atom is non-magnetic in Tb2Fe2Si2C. © 2015 Elsevier B.V.
- ItemMagnetic ordering in TmGa(IOP Science, 2014-03-03) Cadogan, JM; Stewart, GA; Muñoz-Pérez, S; Cobas, R; Hansen, BR; Avdeev, M; Hutchison, WDWe have determined the magnetic structure of the intermetallic compound TmGa by high-resolution neutron powder diffraction and 169Tm Mössbauer spectroscopy. This compound crystallizes in the orthorhombic (Cmcm) CrB-type structure and its magnetic structure is characterized by magnetic order of the Tm sublattice along the a-axis. The initial magnetic ordering occurs at 15(1) K and yields an incommensurate antiferromagnetic structure described by the propagation vector k1 = [0 0.275(2) 0]. At 12 K the dominant ferromagnetic ordering of the Tm sublattice along the a-axis develops in what appears to be a first-order transition. At 3 K the magnetic structure of TmGa is predominantly ferromagnetic but a weakened incommensurate component remains. The ferromagnetic Tm moment reaches 6.7(2) μB at 3 K and the amplitude of the remaining incommensurate component is 2.7(4) μB. The 169Tm hyperfine magnetic field at 5 K is 631(1) T. © Copyright IOP Publishing
- ItemMagnetism and magnetocaloric effect of Mn0.98Fe0.02CoGe(Wiley Online Library, 2014-03-26) Ren, QY; Hutchison, WD; Wang, JL; Muñoz-Pérez, S; Cadogan, JM; Campbell, SJThe crystallographic and magnetic properties of Mn0.98Fe0.02CoGe have been investigated by X-ray diffraction, dc magnetization and neutron diffraction over the temperature range 20–450 K. The temperature dependence of the phase fractions of the orthorhombic and hexagonal phases is described well by a Gaussian distribution. The Mn0.98Fe0.02CoGe sample exhibits a first-order magneto-structural transition centred at TMS ∼ 297 K of FWHM ∼37 K with a magnetic entropy change of −ΔSM = 24(1) J kg−1 K−1 for ΔB = 0–5 T. Neutron diffraction indicates a ferromagnetic orthorhombic structure below TMS with only the Mn carrying magnetic moment (3.98(6) µB) at 20 K. The sample is paramagnetic in the hexagonal phase above TMS.© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
- ItemThe magneto-structural transition in magnetocaloric Mn1-xFexCoGe(Australian Institute of Physics, 2015-02-03) Ren, QY; Hutchison, WD; Wang, JL; Studer, AJ; Din, MFM; Muñoz-Pérez, S; Cadogan, JM; Campbell, SJMagnetic refrigeration techniques based on the magnetocaloric effect are considered an increasingly viable alternative to conventional gas-compression refrigerant, particularly with energy-saving and environmental aspects in mind. Following the discovery of a large magnetocaloric effect in Gd5Si2Ge2, researchers have shifted their attention to investigation of materials exhibiting magneto-structural transitions where large magnetic entropy changes are expected. MnCoGe-based compounds are promising materials for the exploration of large magnetocaloric effects. They are relatively cheap (no rare earth elements) and, importantly, allow an appropriate temperature window (275 – 345 K) around room temperature in which the magneto-structural transition may be positioned. It has been established that Fe is a suitable substitute for Mn to ‘tune’ the structural transition temperature and hence obtain a magneto-structural transition. Here we present the results of a detailed investigation of the structural and magnetic properties and magnetocaloric effect for a range of as-prepared Mn1-xFexCoGe alloys (x = 0.01, 0.02, 0.03 and 0.04) using temperature variable x-ray diffraction (20 – 310 K), neutron diffraction (5 – 450 K) and physical properties measurement system (PPMS, 5 – 300 K). Particular attention will focus on analysis of neutron diffraction data for Mn0.98Fe0.02CoGe and the nature of the magnetic phase transition in Mn0.98Fe0.02CoGe.
- ItemSpin-reorientation in DyGa(Elsevier, 2015-09-15) Susilo, RA; Cadogan, JM; Muñoz-Pérez, S; Cobas, R; Hutchison, WD; Avdeev, MWe have used neutron powder diffraction to determine the magnetic structure of DyGa. This compound crystallises in the orthorhombic CrB-type structure with the Cmcm space group (#63) and the magnetic structure comprises ferromagnetic order of the Dy sublattice along the c-axis below TC=115K. Upon cooling below 25K, the Dy magnetic moments cant away from the c-axis towards the a-axis. At 3K, the Dy moment is 9.8(2) μB and the Dy magnetic moments point in the direction θ=22(2)°, ϕ=0° relative to the c-axis. © 2015 Elsevier B.V.
- ItemSpin-reorientation in DyGa(Australian Institute of Physics, 2014-02-05) Susilo, RA; Cadogan, JM; Cobas, R; Muñoz-Pérez, S; Avdeev, MThe RGa compounds crystallize in the orthorhombic CrB-type structure (Cmcm space-group), which can be viewed as a stacking of trigonal prisms along the crystallographic a-axis with rare earth atoms at the corners and the gallium atoms nearly at the centres. They order ferromagnetically with a Curie temperature ranging from a high of ~187 K in GdGa to a low of 15 K for TmGa. DyGa is a ferromagnet with a Curie temperature (TC) of 115(2) K. Based on single-crystal susceptibility measurements by Shohata, the easy direction of magnetic order was found to be along the c-axis. Recently, Zhang et al. reported a weak shoulder at ~25 K in their magnetization data, which might correspond to a spin-reorientation . In this report, we present our neutron diffraction results to investigate the magnetic ordering of DyGa. Despite the substantial neutron absorption by the Dy (50 at.% of the sample), refinement of our neutron diffraction patterns confirms the c-axis order below TC. Furthermore, upon cooling below 25 K we observe a canting of the Dy moments away from the c-axis towards the a-axis. At 3 K, the Dy moment is 9.8(2) µB and the Dy magnetic moments point in the direction θ = 22(2)° with respect to the crystallographic c-axis.