A5027615435- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Rare-earth and actinide compounds
- Multiferroics and related materials
- Magnetic Properties of Alloys
- Physics of Superconductivity and Magnetism
- X-ray Diffraction in Crystallography
- Nuclear Physics and Applications
- High-pressure geophysics and materials
- Iron-based superconductors research
- Crystallization and Solubility Studies
- Nuclear materials and radiation effects
- Magnetic properties of thin films
- Atomic and Subatomic Physics Research
- Nuclear Materials and Properties
- Machine Learning in Materials Science
- Topological Materials and Phenomena
- Semiconductor materials and interfaces
- Crystallography and molecular interactions
- Shape Memory Alloy Transformations
- Theoretical and Computational Physics
- Boron and Carbon Nanomaterials Research
- 2D Materials and Applications
- Crystal Structures and Properties
- Inorganic Chemistry and Materials
Oak Ridge National Laboratory
2016-2025
Government of the United States of America
2022
University of Tennessee at Knoxville
2021
Paul Scherrer Institute
2013-2020
Quantum Science Center
2016-2017
University of Antwerp
2015
TU Dresden
2004-2011
University of Göttingen
2007
We present synchrotron x-ray diffraction, neutron powder and time-of-flight inelastic scattering measurements on the rare earth pyrochlore oxide ${\mathrm{Nd}}_{2}{\mathrm{Zr}}_{2}{\mathrm{O}}_{7}$ to study ordered state magnetic structure cystal-field states. The structural characterization by high-resolution diffraction confirms that has no detectable O vacancies or Nd/Zr site mixing. reveals long-range all-in/all-out antiferromagnetic order below ${T}_{\mathrm{N}}\ensuremath{\approx}0.4$...
Abstract Low dimensional quantum magnets are interesting because of the emerging collective behavior arising from strong fluctuations. The one-dimensional (1D) S = 1/2 Heisenberg antiferromagnet is a paradigmatic example, whose low-energy excitations, known as spinons, carry fractional spin 1/2. These modes can be reconfined by application staggered magnetic field. Even though considerable progress has been made in theoretical understanding such magnets, experimental realizations this...
A reassessment of the ground state a quantum spin liquid candidate suggests is sensitive to imperceptible change in chemical composition, an insight that could help tuning system exotic, quantum-disordered phases.
We present a comparative study of hydrogen gas adsorption experiments on CPO-27–Cu and –Mn. The initial isosteric heat in is low for material containing open metal sites contrast to the other members CPO-27 series, including Mn compound.
The experimental realization of magnetic skyrmion crystals in centrosymmetric materials has been driven by theoretical understanding how a delicate balance anisotropy and frustration can stabilize topological spin structures applied fields. Recently, the material Gd_{2}PdSi_{3} was shown to host field-induced crystal, but stabilization mechanism remains unclear. Here, we employ neutron-scattering measurements on an isotopically enriched polycrystalline sample quantify interactions that drive...
We demonstrate the first live, autonomous control over neutron diffraction experiments by developing and deploying ANDiE: explorer. Neutron scattering is a unique versatile characterization technique for probing magnetic structure behavior of materials. However, instruments at facilities in world limited, such are perennially oversubscribed. significant reduction experimental time required implementation navigation measurement parameter space through machine learning. Prior scientific...
Spiral spin liquids are correlated paramagnetic states with degenerate propagation vectors forming a continuous ring or surface in reciprocal space. On the honeycomb lattice, spiral present novel route to realize emergent fracton excitations, quantum liquids, and topological textures, yet experimental realizations remain elusive. Here, using neutron scattering, we show that liquid is realized van der Waals magnet FeCl_{3}. A of scattering directly observed, which indicates emergence an...
Joint inelastic neutron and x-ray scattering measurements have been performed on heavy water across the melting point. The spectra bear clear evidence of low- high-frequency shoulders related to transverse longitudinal modes, respectively. Upon increasing momentum transfer, spectral shape evolves from a viscoelastic regime, where low-frequency mode is clearly over-damped, toward an elastic one its propagation becomes instead allowed. crossover between two regimes occurs whenever both...
The charge ordered structure of ions and vacancies characterizing rare-earth pyrochlore oxides serves as a model for the study geometrically frustrated magnetism. organization magnetic into networks corner-sharing tetrahedra gives rise to highly correlated phases with strong fluctuations, including spin liquids ices. It is an open question how these ground states governed by local rules are affected disorder. In Tb$_2$Hf$_2$O$_7$, we demonstrate that vicinity disordering transition towards...
We report detailed thermodynamic studies on high-quality single crystals of the centrosymmetric skyrmion-hosting intermetallic Gd2PdSi3 by means high-resolution capacitance dilatometry in fields up to 15 T which are complemented specific heat and magnetization studies. Our dilatometric measurements show magnetoelastic effects associated with antiferromagnetic order at TN1 = 22.3 K TN2 19.7 K, as well strong field an applied magnetic Tup 200 (150 K) for B||c (B||a*, i.e. B perp c). The data...
In this paper detailed neutron scattering measurements of the magnetic excitation spectrum CuCrO$_2$ in ordered state below $T_{\rm{N1}}=24.2$ K are presented. The spectra analyzed using a model Hamiltonian which includes intralayer-exchange up to next-next-nearest neighbor and interlayer-exchange. We obtain definite parameter set show that exchange interaction terms beyond next-nearest important describe inelastic spectrum. ground structure generated with our is agreement proposed for from...
The suppression of magnetic order with pressure concomitant the appearance pressure-induced superconductivity was recently discovered in CrAs. Here we present a neutron diffraction study evolution helimagnetic ground state towards and vicinity superconducting phase. Neutron on polycrystalline CrAs employed from zero to 0.65 GPa at various temperatures. long-range is sustained under propagation vector does not show any considerable change. average ordered moment reduced 1.73(2)...
Orthorhombic perovskites provide a perfect playground for investigations of novel magnetic phenomena, such as ferroelectricity, ultrafast spin reorientation, colossal magnetoresistance, and many others. Here, the authors combined magnetization neutron scattering measurements with crystalline electrical field calculations to characterize properties DyScO${}_{3}$ single crystal. They establish that Dy moments have strong Ising-like single-ion anisotropy doublet ground state an enormous value...
We report the structural, magnetic, and thermodynamic properties of double perovskite compound ${\mathrm{La}}_{2}{\mathrm{CuIrO}}_{6}$ from x-ray, neutron diffraction, depolarization, $\mathit{dc}$ magnetization, $\mathit{ac}$ susceptibility, specific heat, muon-spin-relaxation $(\ensuremath{\mu}\mathrm{SR})$, electron-spin-resonance (ESR) nuclear magnetic resonance (NMR) measurements. Below $\ensuremath{\sim}113$ K, short-range spin-spin correlations occur within ${\mathrm{Cu}}^{2+}$...
The $R$${}_{2}$PdSi${}_{3}$ intermetallic compounds have been reported to crystallize in a hexagonal AlB${}_{2}$-derived structure, with the rare earth atoms on Al sites and Pd Si randomly distributed B sites. However, intricate magnetic properties observed series of always suggested complications assumed structure. To clarify situation, x-ray neutron diffraction measurements were performed heavy $R=\text{Gd}$, Tb, Dy, Ho, Er, Tm, which revealed existence crystallographic superstructure....
Determining the fate of Pauling entropy in classical spin ice material Dy$_2$Ti$_2$O$_7$ with respect to third law thermodynamics has become an important test case for understanding existence and stability ice-rule states general. The standard model - dipolar predicts ordering transition at $T\approx 0.15$ K, but recent experiments by Pomaranski $et\ al.$ suggest recovery over long time scales temperatures as high $0.5$ much too be compatible theory. Using neutron scattering specific heat...
Abstract Ba 3 Yb 2 Zn 5 O 11 is exceptional among breathing pyrochlore compounds for being in the nearly-decoupled limit where inter-tetrahedron interactions are weak, hosting isolated clusters or molecular magnet-like tetrahedra of magnetic ytterbium (Yb 3+ ) ions. In this work, we present study carried out on single-crystal samples , using a variety magnetometry and neutron scattering techniques along with theoretical modeling. We employ inelastic to investigate dynamics as function...
The magnetic structure, magnetoresistance, and Hall effect of non-centrosymmetric semimetal NdAlGe are investigated revealing an unusual state anomalous transport properties that associated with the electronic structure this compound. magnetization magnetoresistance measurements both highly anisotropic indicate Ising-like system. is complex in it involves three ordering vectors including incommensurate spin density wave commensurate ferrimagnetic zero field. We have discovered a large...
Measurements of the low-energy electronic structure in ${\mathrm{Gd}}_{2}{\mathrm{PdSi}}_{3}$ and ${\mathrm{Tb}}_{2}{\mathrm{PdSi}}_{3}$ by means angle-resolved photoelectron spectroscopy reveal a Fermi surface consisting an electron barrel at $\ensuremath{\Gamma}$ point surrounded spindle-shaped pockets originating from same band. The calculated momentum-dependent RKKY coupling strength is peaked $\frac{1}{2}\ensuremath{\Gamma}K$ wave vector, which coincides with propagation vector...
In this paper we report low-temperature magnetic properties of the rare-earth perovskite material ${\mathrm{YbAlO}}_{3}$. Results elastic and inelastic neutron scattering experiment, magnetization measurements along with crystalline electrical field (CEF) calculations, suggest that ground state Yb moments is a strongly anisotropic Kramers doublet, are confined in $ab$ plane, pointing at an angle $\ensuremath{\varphi}=\ifmmode\pm\else\textpm\fi{}23.{5}^{\ensuremath{\circ}}$ to $a$ axis. With...