A5035977196- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Multiferroics and related materials
- Nuclear Physics and Applications
- Rare-earth and actinide compounds
- Atomic and Subatomic Physics Research
- High-pressure geophysics and materials
- Nuclear materials and radiation effects
- Quantum, superfluid, helium dynamics
- Theoretical and Computational Physics
- Advanced Thermoelectric Materials and Devices
- Material Dynamics and Properties
- Magnetic Properties of Alloys
- Radiation Detection and Scintillator Technologies
- Advanced NMR Techniques and Applications
- Iron-based superconductors research
- NMR spectroscopy and applications
- Magnetic properties of thin films
- Thermal properties of materials
- Inorganic Fluorides and Related Compounds
- Spectroscopy and Quantum Chemical Studies
- Protein Structure and Dynamics
- Magnetism in coordination complexes
- Chalcogenide Semiconductor Thin Films
Oak Ridge National Laboratory
2015-2024
Quantum Science Center
2013-2020
Oak Ridge Associated Universities
2015-2020
Proportional Technologies
2019
Heinz Maier-Leibnitz Zentrum
2018
Forschungszentrum Jülich
2018
Louisiana State University
2018
University of Tennessee at Knoxville
2016-2017
European Spallation Source
2015
Rutherford Appleton Laboratory
2010
The design and performance of the new cold neutron chopper spectrometer (CNCS) at Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover same energy momentum transfer ranges as IN5 ILL, LET ISIS, DCS NIST, TOFTOF FRM-II, AMATERAS J-PARC, PHAROS LANSCE, NEAT HZB, similar resolution. Measured values key figures such flux sample position resolution compared between measurements ray tracing Monte Carlo...
The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) first-principles calculations. experiments show that, surprisingly, although is closer to the ferroelectric instability, phonon spectra in exhibit a more character. This behavior reproduced calculations temperature-dependent self-energy. Our simulations reveal how nesting dispersions induces prominent features self-energy, which account for measured INS...
We present single-crystal neutron scattering measurements of the spin-1/2 equilateral triangular lattice antiferromagnet Ba$_3$CoSb$_2$O$_9$. Besides confirming that Co$^{2+}$ magnetic moments lie in ab plane for zero field, we determine all exchange parameters minimal quasi-2D spin Hamiltonian, which confirms Ba$_3$CoSb$_2$O$_9$ is an almost perfect realization paradigmatic model frustrated quantum magnetism. A comparison with linear and nonlinear spin-wave theory reveals fluctuations...
The Spallation Neutron Source at Oak Ridge National Laboratory now hosts four direct geometry time-of-flight chopper spectrometers. These instruments cover a range of wave-vector and energy transfer space with varying degrees neutron flux resolution. regions reciprocal available to measure these are not exclusive overlap significantly. We present comparison the capabilities this instrumentation, conducted by data mining instrument usage histories, specific scanning regimes. In addition, one...
Intrinsically low lattice thermal conductivity ([Formula: see text]) in superionic conductors is of great interest for energy conversion applications thermoelectrics. Yet, the complex atomic dynamics leading to superionicity and ultralow remain poorly understood. Here, we report a comprehensive study diffusion [Formula: text] from energy- momentum-resolved neutron X-ray scattering techniques, combined with first-principles calculations. Our results settle unresolved questions about...
Phytoglycogen is a naturally occurring polysaccharide nanoparticle made up of extensively branched glucose monomers. It has number unusual and advantageous properties, such as high water retention, low viscosity, stability in water, which make this biomaterial promising candidate for wide variety applications. In study, we have characterized the structure hydration aqueous dispersions phytoglycogen nanoparticles using neutron scattering. Small angle scattering results suggest that behave...
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...
Abstract The quest for advanced superionic materials requires understanding their complex atomic dynamics, but detailed studies of the interplay between lattice vibrations and ionic diffusion remain scarce. Here inelastic quasielastic neutron scattering measurements in argyrodite Cu 7 PSe 6 are reported, combined with molecular dynamics (MD) based on ab initio machine‐learned potentials, providing critical insights into atomistic mechanisms underlying fast ion conduction. results reveal how...
The geometrically frustrated antiferromagnet Gd2Ti2O7 exhibits magnetic behaviour of such complexity that it poses a challenge to both experiment and theory. Magnetic ordering commences at TN = 1.1 K there is further phase transition K. Here we use neutron diffraction definitively establish the nature structure adopted below this temperature. Between partly ordered, as previously reported. Below remaining spins order, but only weakly. in temperature range shown be 4-k structure, closely...
Measurements of the phonon density states by inelastic neutron time-of-flight scattering and specific-heat measurements along with first-principles calculations, provide compelling evidence for existence an Einstein oscillator (rattler) at ${\ensuremath{\omega}}_{E1}\ensuremath{\approx}5.0\text{ }\text{meV}$ in filled skutterudite ${\text{Yb}}_{0.2}{\text{Co}}_{4}{\text{Sb}}_{12}$. Multiple dispersionless modes measured ${\text{Yb}}_{0.2}{\text{Co}}_{4}{\text{Sb}}_{12}$ intermediate transfer...
Orbitals and charge go their separate ways In certain materials at very low temperatures, an electron's spin can from its charge, zooming through the crystal in form of a “spinon.” Such are usually one-dimensional, atoms have spins 1/2. Wu et al. observed related behavior three-dimensional metal, Yb 2 Pt Pb, where ions large magnetic moment that has origin electrons' orbital motion rather than spin. Neutron-scattering measurements indicated these moments flip direction exchange process...
There is tremendous interest in understanding the role that secondary structure plays rigidity and dynamics of proteins. In this work we analyze nanomechanical properties proteins chosen to represent different structures: α-helices (myoglobin bovine serum albumin), β-barrels (green fluorescent protein), α + β loop structures (lysozyme). Our experimental results show these model proteins, motif a stiffer structural unit than α-helix both dry hydrated states. This difference appears not only...
The structure and lattice dynamics of rock-salt thermoelectric materials SnTe PbTe are investigated with single-crystal powder neutron diffraction, inelastic scattering (INS), first-principles simulations. Our calculations the radial distribution function in both show a clear asymmetry first nearest-neighbor (1NN) peak, which increases temperature, agreement recent experimental reports. We that this peak for 1NN Sn-Te or Pb-Te bond results from large-amplitude anharmonic vibrations...
The structurally and dynamically perturbed hydration shells that surround proteins biomolecules have a substantial influence upon their function stability. This makes the extent degree of water perturbation practical interest for general biological study industrial formulation. We present an experimental description dynamical around green fluorescent protein in solution. Less than two (∼5.5 Å) were perturbed, with dynamics factor 2–10 times slower bulk water, depending on distance from...
The spin glass behavior of Y2Mo2O7 has puzzled physicists for nearly three decades. Free bulk disorder within the resolution powder diffraction methods, it is thought that this material a rare realization resulting from weak such as bond or local lattice distortions. Here, we report on single crystal growth Y2Mo2O7. Using neutron scattering, present unique isotropic magnetic diffuse scattering arising beneath transition despite having well-ordered structure at level. Despite our attempts to...
Abstract The lattice dynamics and high-temperature structural transition in SnS SnSe are investigated via inelastic neutron scattering, high-resolution Raman spectroscopy anharmonic first-principles simulations. We uncover a spectacular, extreme softening reconstruction of an entire manifold low-energy acoustic optic branches across transition, reflecting strong directionality bonding strength anharmonicity. Further, our results solve prior controversy by revealing the soft-mode mechanism...