A5054493448- Magnetic and transport properties of perovskites and related materials
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Multiferroics and related materials
- Advanced Condensed Matter Physics
- Distributed and Parallel Computing Systems
- Nuclear Physics and Applications
- High-pressure geophysics and materials
- Scientific Computing and Data Management
- Magnetic Properties of Alloys
- Research Data Management Practices
- Advanced Data Storage Technologies
- Nuclear reactor physics and engineering
- Color perception and design
- Computer Graphics and Visualization Techniques
- Intellectual Capital and Performance Analysis
- X-ray Diffraction in Crystallography
- Hydrocarbon exploration and reservoir analysis
- Radiation Detection and Scintillator Technologies
- Cloud Computing and Resource Management
- Crystallography and Radiation Phenomena
- Atomic and Subatomic Physics Research
- Virtual Reality Applications and Impacts
- Augmented Reality Applications
- Inorganic Chemistry and Materials
Oak Ridge National Laboratory
2013-2024
Government of the United States of America
2022
Physical Sciences (United States)
2016
University of Tennessee at Knoxville
2016
Iowa State University
2012-2013
Ames National Laboratory
2009-2013
Data reduction is a critical step in small-angle neutron scattering experiment. It corrects the data for instrument-specific artefacts, making it ready analysis, interpretation, as well comparison against collected with different instruments. Here, drtsans software package developed at Oak Ridge National Laboratory EQ-SANS, GP-SANS, and Bio-SANS instruments, which are located Spallation Neutron Source High Flux Isotope Reactor, described. The rigorous development methods employed have...
Sunny is a Julia package designed to serve the needs of quantum magnetism community. It supports specification very broad class spin models and diverse suite numerical solvers. These include powerful methods for simulating dynamics both in out equilibrium. Uniquely, it features generalization classical semiclassical approaches SU(N) coherent states, which useful studying systems exhibiting strong spin-orbit coupling or local entanglement effects. also offers well-developed framework...
Spin waves in the rare earth orthorferrite YFeO$_3$ have been studied by inelastic neutron scattering and analyzed with a full four-sublattice model including contributions from both weak ferromagnetic hidden antiferromagnetic orders. Antiferromagnetic (AFM) exchange interactions of $J_1 = -4.23 \pm 0.08$ (nearest-neighbors only) or -4.77 meV $J_2 -0.21 0.04$ lead to excellent fits for most branches at low high energies. An additional branch associated order was observed. This work paves way...
We have performed detailed studies of the temperature evolution electronic structure in Ba(Fe(1-x)Ru(x))2As2 using Angle Resolved Photoemission Spectroscopy (ARPES). Surprisingly, we find that binding energy both hole and electron bands changes significantly with pure Ru substituted samples. The pockets are well nested at low unsubstituted (BaFe2As2) samples, which likely drives spin density wave (SDW) resulting antiferromagnetic order. Upon warming, this nesting is degraded as pocket...
Abstract Localized spins and itinerant electrons rarely coexist in geometrically-frustrated spinel lattices. They exhibit a complex interplay between localized electrons. In this paper, we study the origin of unusual spin structure CoV 2 O 4 , which stands at crossover from insulating to behavior using first principle calculation neutron diffraction measurement. contrast expected paramagnetism, supported by enhanced exchange couplings are frustrated effects delocalized This frustration...
We report elastic and inelastic neutron-scattering measurements of the high-${T}_{\mathrm{C}}$ ferromagnet ${\mathrm{Mn}}_{1+\ensuremath{\delta}}\mathrm{Sb}$. Measurements were performed on a large, ${T}_{\mathrm{C}}=434$ K, single crystal with an interstitial Mn content $\ensuremath{\delta}\ensuremath{\approx}0.13$. The neutron-diffraction results reveal that has magnetic moment, it is aligned antiparallel to main moment. perform density functional theory calculations including find be...
The crossover from localized to itinerant electron regimes in the geometrically frustrated spinel system ${\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}{\mathrm{V}}_{2}{\mathrm{O}}_{4}$ is explored by neutron-scattering measurements, first-principles calculations, and spin models. At low Co doping, orbital ordering (OO) of ${\mathrm{V}}^{3+}$ spins suppresses magnetic frustration triggering a tetragonal distortion. high doping levels, however, electronic itinerancy melts OO lessens...
The high-temperature ferromagnet MnBi continues to receive attention as a candidate replace rare-earth-containing permanent magnets in applications above room temperature. This is due high Curie temperature, large magnetic moments, and coercivity that increases with synthesis of also allows for crystals are free interstitial Mn, enabling more direct access the key interactions underlying physical properties binary Mn-based ferromagnets. In this work, we use inelastic neutron scattering...
In the iron pnictides, strong sensitivity of magnetic moment to arsenic position suggests a significant relationship between phonons and magnetism. We measured phonon dispersion several branches in high-temperature tetragonal phase ${\text{CaFe}}_{2}{\text{As}}_{2}$ using inelastic x-ray scattering on single-crystal samples. These measurements were compared ab initio calculations phonons. Spin-polarized imposing antiferromagnetic order present low-temperature orthorhombic dramatically...
In this paper, we propose strategies and objectives for immersive data visualization with applications in materials science using the Oculus Rift virtual reality headset. We provide background on currently available analysis tools neutron scattering other large-scale projects. context of current challenges facing scientists, discuss as a potentially powerful solution. introduce prototype system, developed conjunction scientists at Spallation Neutron Source, which have used to explore large...
Magnetic order and low-energy spin dynamics in the zero field ground state of Ni${}_{3}$V${}_{2}$O${}_{8}$ are revealed elastic inelastic neutron scattering experiments. Neutron diffraction shows that below $T=2.3$ K Ni${}^{2+}$ moments (spin $S=1$) a cycloid pattern with incommensurate wave vector ${\mathbit{k}}_{\text{ICM}}=(0,1,\ensuremath{\tau})$, where $\ensuremath{\tau}=0.4030\ifmmode\pm\else\textpm\fi{}0.0004$, which is superimposed on commensurate antiferromagnetic arrangement...
Event-mode data collection presents remarkable new opportunities for time-of-flight neutron scattering studies of collective excitations, diffuse from short-range atomic and magnetic structures, crystallography. In these experiments, large volumes the reciprocal space are surveyed, often using different wavelengths counting times. These then have to be added together, with accurate propagation errors. This paper a statistically correct way adding histogramming single-crystal measurements....
The phonon dispersion was measured at room temperature along (0,0,L) in the tetragonal phase of LaFeAsO using inelastic x-ray scattering. Spin-polarized first-principles calculations imposing various types antiferromagnetic order are better agreement with experimental results than nonmagnetic calculations, although measurements were made well above magnetic ordering temperature, T_N. Splitting observed between two A_{1g} modes 22 and 26 meV is only spin-polarized calculations....
Data reduction is a critical step in small-angle neutron scattering experiment. It corrects the data for instrument-specific artefacts, making it ready analysis, interpretation, as well comparison against collected with different instruments. Here, drtsans software package developed at Oak Ridge National Laboratory EQ-SANS, GP-SANS, and Bio-SANS instruments, which are located Spallation Neutron Source High Flux Isotope Reactor, described. The rigorous development methods employed have...
Monte Carlo ray tracing simulations, of direct geometry spectrometers, have been particularly useful in instrument design and characterization. However, these tools can also be for experiment planning analysis. To this end, the McStas model SEQUOIA, fine resolution fermi chopper spectrometer at Spallation Neutron Source (SNS) Oak Ridge National Laboratory (ORNL), has modified to include time flight sample detector components. With components, ellipsoid calculated any pixel energy bin...
Mantid: A high performance framework for the reduction and analysis of muon spin resonance neutron scattering data.
Oak Ridge National Laboratory (ORNL) experimental neutron science facilities produce 1.2\,TB a day of raw event-based data that is stored using the standard metadata-rich NeXus schema built on top HDF5 file format. Performance several reduction workflows largely determined by amount time spent loading and processing algorithms in Mantid, an open-source analysis framework used across sciences around world. The present work introduces new management to address identified input output (I/O)...
The ORNL Spallation Neutron Source (SNS) provides the most intense pulsed neutron beams in world for scientific research and development across a broad range of disciplines. SNS experiments produce large volumes complex data that are analyzed by scientists with varying degrees experience using 3D visualization analysis systems. However, it is notoriously difficult to achieve proficiency visualizations. Because representations key understanding scattering data, unable analyze their timely...
Many areas of science exhibit physical processes that are described by high dimensional partial differential equations (PDEs), e.g., the 4D (Dorf et al., 2013), 5D (Candy 2009) and 6D models (Juno 2018) describing magnetized fusion plasmas, quantum chemistry, or derivatives pricing (Bandrauk 2007).Such problems affected so-called "curse dimensionality" where number degrees freedom (or unknowns) required to be solved for scales as is grid points in any given dimension .A simple, albeit naive,...