A5039889392- Advanced Condensed Matter Physics
- Multiferroics and related materials
- Magnetic and transport properties of perovskites and related materials
- Nuclear materials and radiation effects
- Physics of Superconductivity and Magnetism
- High-pressure geophysics and materials
- Semiconductor materials and devices
- Crystal Structures and Properties
- Geological and Geochemical Analysis
- Ferroelectric and Piezoelectric Materials
- Electronic and Structural Properties of Oxides
- Theoretical and Computational Physics
- Semiconductor materials and interfaces
- Anodic Oxide Films and Nanostructures
- Diamond and Carbon-based Materials Research
- Magnetic properties of thin films
- Topological Materials and Phenomena
- Quantum many-body systems
- Catalysis and Oxidation Reactions
- Metal-Organic Frameworks: Synthesis and Applications
- Mineralogy and Gemology Studies
- Silicon Nanostructures and Photoluminescence
- ZnO doping and properties
- Ferroelectric and Negative Capacitance Devices
- Inorganic Fluorides and Related Compounds
Institut de Chimie Moléculaire et des Matériaux d'Orsay
2015-2024
Centre National de la Recherche Scientifique
2008-2024
Université Paris-Saclay
2015-2024
Université Paris-Sud
2010-2019
CEA Paris-Saclay
2016
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2016
Institut Lavoisier de Versailles
2008-2009
The pyrochlore oxides (A2B2O7) exhibit a remarkable range of structural, physical, and magnetic properties related to their various chemical compositions. This article reports the phase transformations induced by high electronic excitation in pyrochlores Gd2(ZrxTi1−x)2O7 family irradiated with swift ions. structural changes, investigated using several analytical techniques (x-ray diffraction, Raman spectroscopy, transmission electron microscopy), strongly depend on composition. along ion...
We studied the field induced magnetic order in ${R}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ pyrochlore compounds with either uniaxial ($R=\mathrm{Ho}$, Tb) or planar ($R=\mathrm{Er}$, Yb) anisotropy, by polarized neutron diffraction. The determination of local susceptibility tensor ${{\ensuremath{\chi}}_{\ensuremath{\Vert}},{\ensuremath{\chi}}_{\ensuremath{\perp}}}$ provides a universal description structures paramagnetic phase (2--270 K), whatever value (1--7 T) and direction. Comparison...
In this work, we show that the zero field excitation spectra in quantum spin ice candidate pyrochlore compound \ybti\ is a continuum characterized by very broad and almost flat dynamical response which extends up to $1-1.5$ meV, coexisting or not with quasi-elastic depending on wave-vector. The do evolve between 50 mK 2 K, indicating dynamics only little affected temperature both short-range correlated ordered regimes. Although classical simulations qualitatively capture some of experimental...
We present an experimental study of the quantum spin ice candidate pyrochlore coumpound \przr\ by means magnetization measurements, specific heat and neutron scattering up to 12 T down 60 mK. When field is applied along $[111]$ $[1\bar{1}0]$ directions, ${\bf k}=0$ induced structures settle in. find that ordered moment rises slowly, even at very low temperature, in agreement with macroscopic magnetization. Interestingly, for $H \parallel [1\bar{1}0]$, appears on so called $\alpha$ chains...
We have studied the low-energy spin dynamics between 4.6 and 0.07 K in a Tb${}_{2}$Ti${}_{2}$O${}_{7}$ single-crystal sample by means of inelastic neutron scattering experiments. The spectra consist dual response, with static an contribution, showing striking $Q$ dependencies. propose interpretation involving anisotropic exchange interaction combination breaking threefold symmetry at rare earth site. Simulations $Q$-dependent random phase approximation account well for response.
The dynamical magnetic correlations in ${\mathrm{Tb}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ have been investigated using polarized inelastic neutron scattering. Dispersive excitations are observed, emerging from pinch points reciprocal space and characterized by an anisotropic spectral weight. Anomalies the crystal field phonon excitation spectrum at Brillouin zone centers also reported. These findings suggest that Coulomb phases, although they present a disordered ground state with dipolar...
The structural transformations induced in Gd${}_{2}$Ti${}_{2}$O${}_{7}$ single crystals irradiated at high energies (870-MeV Xe), where ionization processes (electronic stopping) dominate, and low (4-MeV Au), ballistic (nuclear have been studied via the combination of Rutherford backscattering spectrometry channeling (RBS/C), Raman spectroscopy, transmission electron microscopy (TEM) experiments. At energy, amorphization occurs directly individual ion tracks from extreme electronic-energy...
Examples of materials where an ``order by disorder'' mechanism is at play to select a particular ground state are scarce. It has recently been proposed, however, that the antiferromagnetic XY pyrochlore ${\mathrm{Er}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ reveals most convincing case this mechanism, with observation spin gap zone centers having interpreted as corroboration physics. Here we argue, anisotropy generated interaction-induced admixing between crystal-field and excited levels...
Randomness in the arrangement of molecules within certain types frustrated magnets may offer a way to promote and stabilize exotic states matter known as spin liquids. New neutron-scattering experiments characterize disorder ice candidate Pr${}_{2}$Zr${}_{2}$O${}_{7}$ provide an explanation for some this material's unique properties.
The preparation, structural, microstructural, dielectric, and low temperature magnetic properties of Mg x Ni 1− Fe 2 O 4 ( = 0, 0.17, 0.34, 0.50, 0.66, 0.83, 1) ferrites synthesized by using a self‐combustion sol–gel method is presented. Good insulating were found for all the compositions at high frequencies (kHz MHz range), which might drive present ceramics as interesting RF /microwaves applications. By increasing 2+ concentration, total resistivity strongly increases (from ~10 6 Ωm...
This article reviews recent achievements on the crystal growth of a new series pyrochlore oxides—lanthanide zirconates, which are frustrated magnets with exotic magnetic properties. Oxides type A 2 B O 7 (where = Rare Earth, Ti, Mo) have been successfully synthesised in single form using floating zone method. The main difficulty employing this technique for rare earth zirconium oxides Zr arises from high melting point these materials. drawback has recently overcome by use power Xenon arc...
We have studied the field-induced magnetic structures of Tb${}_{2}$Ti${}_{2}$O${}_{7}$ pyrochlore by single-crystal neutron diffraction under a field applied along [111] axis, up to $H=12$ T and down $T=40$ mK. refined with $\mathbit{k}=\mathbf{0}$ propagation vector performing symmetry analysis in space group $R\overline{3}m$, reducing number free parameters three only. The Tb moments gradually reorient towards direction, keeping close ``3-in, 1-out / 1-in, 3-out'' spin structure (magnetic...
The origin of quantum fluctuations responsible for the spin liquid state in Tb$_2$Ti$_2$O$_7$ has remained a long standing problem. By synchrotron-based terahertz measurements, we show evidence strong coupling between magnetic and lattice degrees freedom that provides path to melting process. As revealed by hybrid crystal electric field-phonon excitations appear at 0.67 THz below 200 K, around 0.42 50 double vibronic process is unique Tb$^{3+}$ titanate family due adequate energy matching...
In this work, we revisit the crystal field acting on non-Kramers ${\mathrm{Pr}}^{3+}$ ion $(4{f}^{2})$ in quantum spin-ice candidate ${\mathrm{Pr}}_{2}{\mathrm{Zr}}_{2}{\mathrm{O}}_{7}$ using both a standard calculation restricted to ground spin-orbit multiplet and intermediate coupling states full basis of ${f}^{2}$ configuration. Analysis thermal variation polycrystal magnetic susceptibility local susceptibilities ${\ensuremath{\chi}}_{\ensuremath{\perp}}$...
We have measured neutron-diffraction patterns in a single-crystal sample of the pyrochlore compound ${\text{Er}}_{2}{\text{Ti}}_{2}{\text{O}}_{7}$ antiferromagnetic phase $(T=0.3\text{ }\text{K})$, as function magnetic field, up to 6 T, applied along [110] direction. determine all characteristics structure throughout critical point at ${H}_{c}=2\text{ }\text{T}$. As main result, Er moments align field ${H}_{c}$ and their values reach minimum. Using four-sublattice self-consistent...
We have studied the spin correlations with $\mathbf{k}=(\frac{1}{2},\frac{1}{2},\frac{1}{2})$ propagation vector, which appear below 0.4 K in ${\text{Tb}}_{2}{\text{Ti}}_{2}{\text{O}}_{7}$ liquid by combining powder neutron diffraction and specific heat on ${\mathrm{Tb}}_{2+x}{\mathrm{Ti}}_{2\ensuremath{-}x}{\mathrm{O}}_{7+y}$ samples $x=0$, 0.01, $\ensuremath{-}0.01$. The order clearly appears all patterns subtracting a pattern at 1.2(1) K. Refining subtracted 0.07 yields two possible...
Reentrant spin glasses are frustrated disordered ferromagnets developing vortexlike textures under an applied magnetic field. Our study of a ${\mathrm{Ni}}_{0.81}{\mathrm{Mn}}_{0.19}$ single crystal by small angle neutron scattering clarifies their internal structure and shows that these randomly distributed. Spin components transverse to the field rotate over length scales 3--15 nm in explored range, decreasing as increases according scaling law. Monte Carlo simulations reveal vortices is...
Abstract This article reports on the exploration of chemical versatility entropy‐stabilized pyrochlores (A 2 B O 7 ) with large disorder introduced site, as well study isovalent and aliovalent substitution site Ca 2+ ‐doping A site. Among all 20 new compounds obtained in this study, 8 are entropy‐stabilized: RE (TiZrHfGeSn) (with = Gd–Ho Y), Pr (TiZrHfScNb) , (TiGeSnAlNb) Er Y). Moreover, some physical properties (magnetic, electrical, thermal, optical properties) these high‐entropy have...
While the spin-liquid state in frustrated pyrochlore ${\mathrm{Tb}}_{2+x}{\mathrm{Ti}}_{2\ensuremath{-}x}{\mathrm{O}}_{7+y}$ has been studied both experimentally and theoretically for more than two decades, a definite description of this unconventional still needs to be achieved. Using synchrotron-based THz spectroscopy combination with quantum numerical simulations, we highlight significant link between features: existence quadrupolar order following an ice rule presence strong...
Amongst the rare earth pyrochlores, Tb${}_{2}$Ti${}_{2}$O${}_{7}$ remains mysterious: no theory of purely magnetic degrees freedom can account entirely for its behavior. The discovery a hybrid magnetoelastic excitation, formed from crystal field and phonon excitations, suggests that spin-lattice coupling may play an important role. Here, authors use inelastic neutron scattering to make detailed investigation mode excitons hold key understanding microscopic interactions Tb${}_{2}$Ti${}_{2}$O${}_{7}$.