A5041371221- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Multiferroics and related materials
- Physics of Superconductivity and Magnetism
- X-ray Diffraction in Crystallography
- Rare-earth and actinide compounds
- Magnetic Properties and Synthesis of Ferrites
- Crystallization and Solubility Studies
- Magnetic properties of thin films
- Crystal Structures and Properties
- High-pressure geophysics and materials
- Ferroelectric and Piezoelectric Materials
- Magnetic Properties of Alloys
- Theoretical and Computational Physics
- Advanced Thermoelectric Materials and Devices
- Iron-based superconductors research
- Methane Hydrates and Related Phenomena
- Fuel Cells and Related Materials
- Inorganic Fluorides and Related Compounds
- Magneto-Optical Properties and Applications
- Heusler alloys: electronic and magnetic properties
- Advancements in Solid Oxide Fuel Cells
- Copper-based nanomaterials and applications
- Pigment Synthesis and Properties
- Spacecraft and Cryogenic Technologies
Laboratoire Léon Brillouin
2015-2024
CEA Paris-Saclay
2015-2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2015-2024
Centre National de la Recherche Scientifique
2014-2023
Université Paris-Saclay
2017-2023
CEA Paris-Saclay - Etablissement de Saclay
2008-2019
RSPC MT
2019
Laboratoire de Cristallographie et Sciences des Matériaux
1996-2014
Institut Rayonnement-Matière de Saclay
2014
University of Liverpool
2008
Abstract Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns obtained at room temperature and analyzed using Rietveld methods. A linear dependence of unit cell parameters is found. In 3+ cations are located mainly in octahedral positions 4f VI 12 k. The average crystallite size varies within 0.84–0.65 μm. With increasing substitution, T C Curie decreases monotonically down to ~ 520 K. ZFC FC measurements showed...
The study of Mn(IV)-rich manganites ${\mathrm{Ca}}_{1\ensuremath{-}x}{\mathrm{Sm}}_{x}{\mathrm{MnO}}_{3}$ with low electron content corresponding to $0<~x<~0.12$ demonstrates the large difference their electronic and magnetic properties that Mn(III)-rich manganites. In particular, a metalliclike temperature dependence resistivity (\ensuremath{\rho}) is observed above ${T}_{C},$ smallest room-temperature $\ensuremath{\rho}{=10}^{\ensuremath{-}3}\ensuremath{\Omega}\mathrm{cm}$ being reached...
The dynamic magnetic properties of the distorted perovskite system La{0.7-x}Y{x}Ca{0.3}MnO{3} (0 <= x 0.15) have been investigated by ac-susceptibility and dc magnetization measurements, with emphasis on relaxation aging studies. They evidence for >= 0.10 appearance a metallic cluster glass phase, that develops just below ferromagnetic transition temperature. clusters grow decreasing temperature down to T(f0) at which they freeze due severe intercluster frustration. formation these is...
Nanolamellar MAX phase compounds (Cr0.5V0.5)n+1AlCn are formed with n = 1, 2 and 3, their 300 K structure is studied in detail by high-resolution neutron diffraction. While the 1 compound found to have complete disordering of vanadium chromium metallic layers, 3 show strong tendency for these elements' ordering, layer 2a(0,0,0) site (Cr0.5V0.5)3AlC2 fully occupied vanadium. The thermal expansion dependency temperature also diffraction < T 550 K, revealing a negligible below 100 all compounds.
Co$^{2+}$ ions in an octahedral crystal field, stabilise a j$_{eff}$ = 1/2 ground state with orbital degree of freedom and have been recently put forward for realising Kitaev interactions, prediction we tested by investigating spin dynamics two cobalt honeycomb lattice compounds, Na$_2$Co$_2$TeO$_6$ Na$_3$Co$_2$SbO$_6$, using inelastic neutron scattering. We used linear wave theory to show that the magnetic spectra can be reproduced Hamiltonian including dominant nearest-neighbour...
A systematic study of the magnetic properties manganites Ln0.5(A,A′)0.5MnO3 (A,A′=Ba, Ca, Sr) has been carried out. The variations TC and TN vs two parameters, average size interpolated cations 〈rA〉 mismatch effect represented by variance σ2, have studied for series La0.5(A,A′)0.5MnO3, Pr0.5(A,A′)0.5MnO3, Nd0.5(A,A′)0.5MnO3 Sm0.5(A,A′)0.5MnO3 Sr), involving at most three different on perovskite site. results obtained other (Ln, Ln′)0.5Sr0.5MnO3(Ln, Ln′=Gd, Sm Y, Pr) taken into consideration....
Magnetotransport properties of the Mn(IV)-rich perovskites Ca1-xLnxMnO3 and Ca1-xThxMnO3 (0 ≤ x 0.20) have been systematically investigated. Among different factors governing their colossal magnetoresistance (CMR), we demonstrate that electron concentration is predominant one by comparing effects Ln3+ Th4+, optimal value giving highest being twice for former compared to latter, in accordance with respective oxidation states. CMR linked ferromagnetism−antiferromagnetism competition maximum...
The Mn site substitutions of charge ordered (CO) manganites Ln0.5Ca0.5MnO3 (Ln=La–Tb) have been investigated. Among the different studied doping elements, chromium is shown to be most efficient one induce a metal insulator (MI) transition in CO undoped insulators. A new Tm(〈rA〉) magnetic diagram, where 〈rA〉 cationic average radius, established for oxides Ln0.5Ca0.5Mn1−xCrxO3, which demonstrates that not rhedibitory parameter occurrence colossal magnetoresistance (CMR) properties. size limit...
The structural and magnetic transitions in two ${\mathrm{Mn}}^{3+}/{\mathrm{Mn}}^{4+}(1:1)$ systems have been investigated using neutron diffraction electron microscopy. In ${\mathrm{Pr}}_{0.5}{\mathrm{Ca}}_{0.5}{\mathrm{MnO}}_{3},$ the charge orbital order develops paramagnetic phase of Pnma symmetry below ${T}_{\mathrm{co}}=250 \mathrm{K}$ through a sequence incommensurate configurations. ordering process is accomplished at ${T}_{N}=170 where charge-exchange--(CE) type antiferromagnetism...
We have studied the variation of paramagnetic to ferromagnetic transition temperature TC and antiferromagnetic TN as a function average size A site cations (Ln, Sr) in manganite perovskites Ln0.5Sr0.5MnO3 (Ln=Gd, Sm, Y, Pr, La). For our investigation we used dc resistivity, magnetization, susceptibility magnetoresistance measurements. Results show that Curie increases from 85 310 K when 〈rA〉 varies 1.221 1.263 Å, whereas remains stable around 150 K. magnetic phase diagram temperature-〈rA〉...
Delafossite antiferromagnetic oxide ${\text{CuCrO}}_{2}$ was investigated by means of neutron powder diffraction versus temperature. Evolution the structural parameters (in $R\overline{3}m$ hexagonal setting) shows a steady decrease in $a$ lattice parameter but negative thermal expansion along $c$ as temperature decreases from 300 to 1.5 K. Below ${T}_{N}=24\text{ }\text{K}$, both and become constant relaxation rhombohedral distortion ${\text{CrO}}_{6}$ octahedra is observed. The magnetic...
The spin dynamics of the geometrically frustrated triangular antiferromagnet multiferroic CuCrO2 have been mapped out using inelastic neutron scattering. relevant Hamiltonian parameters modelling incommensurate modulated helicoid determined, and correspond to antiferromagnetic nearest next-nearest neighbour interactions in ab plane, with a strong planar anisotropy. weakly dispersive excitation along c reflects essentially two-dimensional character magnetic according classical energy...
Oxides containing magnetic 3d transition metals offer a large family of structures with frustrated networks. Some those incommensurate antiferromagnetic are responsible for the local breaking inversion symmetry so that these oxides called spin-induced ferroelectrics. As listed in introduction this short review, number multiferroics continues to increase. applications, coupling between ferroisms is needed; some oxides, despite lack ferroelectric ground state, exhibit magnetoelectric...
The complexity embedded in condensed matter fertilizes the discovery of new states matter, enriched by ingredients like frustration. Illustrating examples magnetic systems are Kitaev spin liquids, skyrmions phases, or ices. These unconventional ground support exotic excitations, for example charges ices, also called monopoles. Here, we propose a mechanism to inject monopoles ice at equilibrium through staggered field. We show theoretically, and demonstrate experimentally Ho2Ir2O7 pyrochlore...
Heusler compounds having ${D}_{2d}$ crystal symmetry gained much attention recently due to the stabilization of a vortexlike spin texture called antiskyrmions in thin lamellae $\mathrm{M}{\mathrm{n}}_{1.4}\mathrm{P}{\mathrm{t}}_{0.9}\mathrm{P}{\mathrm{d}}_{0.1}\mathrm{Sn}$ as reported work Nayak et al. [Nature (London) 548, 561 (2017)]. Here we show that bulk undergoes spin-reorientation transition from collinear ferromagnetic noncollinear configuration Mn moments below 135 K, which is...
While calcium oxalate monohydrate (whewellite: CaC2O4·H2O) kidney stones are related to hyperoxaluria, dihydrate (weddellite: CaC2O4·(2 + x)H2O) ones mainly associated with hypercalciuria. Crystalline conversion from weddellite whewellite introduces a contradiction between Fourier transform infrared (FTIR) spectra which indicate the presence of and fact that bipyramid crystallites, morphology specific weddellite, can be observed. It constitutes thus major problem for clinicians as...
The compound ${\text{InCu}}_{2/3}{\text{V}}_{1/3}{\text{O}}_{3}$ has been studied by spectroscopy in the IR, near-infrared, and visible regions. X-ray neutron diffraction indicate two-dimensional (2D) structural order of magnetic ${\text{Cu}}^{2+}$ $(S=1/2)$ ions on a honeycomb lattice with nonmagnetic ${\text{V}}^{5+}$ complementing hexagonal layer. Superstructure reflections observed reveal presence this 2D Cu/V domains approximately $300\text{ }\text{\AA{}}$ disordered stacking along $c$...
The temperature evolution of the crystal and magnetic structures ferroelectric sulfide AgCrS${}_{2}$ has been investigated by means neutron scattering. undergoes at ${T}_{N}=41.6$ K a first-order phase transition, from paramagnetic rhombohedral $R$3$m$ structure to an antiferromagnetic monoclinic with polar $\mathit{Cm}$ space group. In addition being below ${T}_{N}$, low-temperature exhibits unconventional collinear that can be described as double ferromagnetic stripes coupled...