A5032190741- Rare-earth and actinide compounds
- Iron-based superconductors research
- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Quasicrystal Structures and Properties
- Diamond and Carbon-based Materials Research
- Superconductivity in MgB2 and Alloys
- Mineralogy and Gemology Studies
- Magnetic Properties of Alloys
- High-pressure geophysics and materials
- Corporate Taxation and Avoidance
- Transition Metal Oxide Nanomaterials
- Multiferroics and related materials
- Nuclear Materials and Properties
- Structural Response to Dynamic Loads
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Fluid Dynamics and Turbulent Flows
- Information Retrieval and Data Mining
- Magneto-Optical Properties and Applications
- Analytic and geometric function theory
- Hip and Femur Fractures
- Tunneling and Rock Mechanics
- Carbon Nanotubes in Composites
Washington State University
2020-2024
Iowa State University
2016-2023
Los Alamos National Laboratory
2013-2022
Ames National Laboratory
2016-2022
Institute of Post Graduate Medical Education and Research
2021-2022
Lawrence Livermore National Laboratory
2021
University of Kalyani
2020
United States Department of Energy
2019
Tata Medical Center
2014
University of Notre Dame
2009-2012
Abstract A hallmark of the iron-based superconductors is strong coupling between magnetic, structural and electronic degrees freedom. However, a universal picture normal state properties these compounds has been confounded by recent investigations FeSe where nematic (structural) magnetic transitions appear to be decoupled. Here, using synchrotron-based high-energy x-ray diffraction time-domain Mössbauer spectroscopy, we show that nematicity magnetism in under applied pressure are indeed...
A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such frequently arise because competition localized and itinerant degrees freedom. Although respective limits well-localized or entirely ground states are well understood, intermediate regime controls functional properties materials continues challenge theoretical understanding. We have used neutron spectroscopy investigate plutonium, which a prototypical at brink...
We have used high-resolution neutron spectroscopy experiments to determine the complete spin wave spectrum of heavy fermion antiferromagnet CeRhIn$_5$. The dispersion can be quantitatively reproduced with a simple $J_1$-$J_2$ model that also naturally explains magnetic spin-spiral ground state CeRhIn$_5$ and yields dominant in-plane nearest-neighbor exchange constant $J_0$ = 0.74 meV. Our results pave way quantitative understanding rich low-temperature phase diagram prominent Ce$T$In$_5$...
We have used specific heat and neutron diffraction measurements on single crystals of ${\mathrm{URu}}_{2\ensuremath{-}x}{\mathrm{Fe}}_{x}{\mathrm{Si}}_{2}$ for Fe concentrations $x\ensuremath{\le}0.7$ to establish that chemical substitution Ru with acts as ``chemical pressure'' ${P}_{ch}$ previously proposed by Kanchanavatee et al. [Phys. Rev. B 84, 245122 (2011)] based bulk polycrystalline samples. Notably, reveals a sharp increase the uranium magnetic moment at $x=0.1$, reminiscent...
CeCoIn5 is a heavy fermion Type-II superconductor which exhibits clear indications of Pauli-limited superconductivity. A variety measurements give evidence for transition at high magnetic fields inside the superconducting state, when field applied either parallel to or perpendicular c axis. When axis, antiferromagnetic order observed on high-field side transition, with wavevector (q q 0.5), where = 0.44 reciprocal lattice units. We show that this remains as rotated out basal plane, but...
We have performed inelastic neutron scattering measurements on powder samples of the quasicrystal approximant, ${\mathrm{TbCd}}_{6}$, grown using isotopically enriched $^{112}\mathrm{Cd}$. Both quasielastic and distinct excitations were observed below 3 meV. The intensity measured in paramagnetic phase diverges as ${T}_{\mathrm{N}}\ensuremath{\sim}22$ K is approached from above. excitations, their evolution with temperature, are well characterized by leading term, ${B}_{2}^{0}{O}_{2}^{0}$,...
We explore the structural evolution of highly oriented pyrolytic graphite (HOPG) under detonation-induced shock conditions using in situ synchrotron x-ray diffraction ns timescale. observe formation hexagonal diamond (lonsdaleite) at pressures above 50 GPa, qualitative agreement with recent gas gun experiments. First-principles density functional calculations reveal that uniaxial compression, energy barrier for transition toward is lower than cubic diamond. Finally, no indication was...
From small-angle neutron scattering studies of the flux line lattice (FLL) in CeCoIn5, with magnetic field applied parallel to crystal c-axis, we obtain field- and temperature-dependence FLL form factor, which is a measure spatial variation mixed state. We extend our earlier work [A.D. Bianchi et al. 2008 Science 319, 177] temperatures up 1250 mK. Over entire temperature range, paramagnetism cores results an increase factor field. Near H_c2 decreases again, indicate that this fall-off...
The vortex lattice (VL) symmetry and orientation in clean type-II superconductors depends sensitively on the host material anisotropy, density temperature, frequently leading to rich phase diagrams. Typically, a well-ordered VL is taken imply ground state configuration for vortex-vortex interaction. Using neutron scattering we studied MgB2 number of field-temperature histories, discovering an unprecedented degree metastability connection with known, second-order rotation transition. This...
We have carried out a careful magnetic neutron scattering study of the heavy fermion compound URu2Si2 to probe possible existence small moment parallel tetragonal basal plane in 'hidden-order' phase. This in-plane component on uranium sites S∥ has been postulated by two recent models (rank-5 superspin/hastatic order) aiming explain hidden-order phase, addition well-known out-of-plane S⊥ ≈ 0.01–0.04 μB/U. In order separate and S⊥, we take advantage condition that for only components structure...
Studying the prototypical ferromagnetic superconductor UGe$_2$ we demonstrate potential of Modulated IntEnsity by Zero Effort (MIEZE) technique---a novel neutron spectroscopy method with ultra-high energy resolution at least 1~$\mu$eV---for study quantum matter. We reveal purely longitudinal spin fluctuations in a dual nature arising from $5f$ electrons that are hybridized conduction electrons. Local perfectly described Ising universality class three dimensions, whereas itinerant occur over...
Iron pnictides and related materials have been a topic of intense research for understanding the complex interplay between magnetism superconductivity. Here we report on magnetic structure SrMn2As2 that crystallizes in trigonal ([Formula: see text]) undergoes an antiferromagnetic (AFM) transition at [Formula: text] K. The susceptibility remains nearly constant temperatures with whereas it decreases significantly text]. This shows ordered Mn moments lie plane instead aligning along text]-axis...
We report on the six-dimensional (6D) structural refinement of three members i-$R$-Cd quasicrystals ($R$ = Gd, Dy, Tm) via synchrotron x-ray diffraction from single-grain samples, and show that this series is isostructural to i-${\mathrm{YbCd}}_{5.7}$ quasicrystal. However, our refinements suggest $R$ occupancy Yb icosahedron sites within Tsai-type atomic cluster approximately 80%, with balance taken up by Cd. Similarities between i-${\mathrm{ScZn}}_{7.33}$, their differences...
Neutron-diffraction and magnetic susceptibility studies of polycrystalline ${\mathrm{SrCr}}_{2}{\mathrm{As}}_{2}$ reveal that this compound is an itinerant G-type antiferromagnet below the N\'eel temperature ${T}_{\mathrm{N}}$ = 590(5) K with Cr moments aligned along tetragonal $c$ axis. The system remains to lowest measured ($\ensuremath{\sim}12$ K). lattice parameter ratio $c/a$ moment saturate at about same $\ensuremath{\sim}200$ K, indicating a possible magnetoelastic coupling. ordered...
FeSe, despite being the structurally simplest compound in family of iron-based superconductors, shows an astoundingly rich interplay physical phenomena including nematicity and pressure-induced magnetism. Here, we present a microscopic study these two by high-energy x-ray diffraction time-domain M\"ossbauer spectroscopy on FeSe single crystals over wide temperature pressure range. The topology pressure-temperature phase diagram is surprisingly close parallel to well-known doping-temperature...
Single-pulse ($\ensuremath{\sim}100$-ps duration) extended x-ray absorption fine structure (EXAFS) measurements were obtained in laser-shocked Pt to examine atomic vibrational properties and determine temperatures for shock pressures from 72 325 GPa. spectra recorded while a planar wave was propagating through the sample. The spectrum corresponding shocked by subtracting ambient contribution measured spectrum. Fits shocked-state EXAFS data provided lattice parameters consistent with known...
We present small angle neutron scattering studies of the vortex lattice (VL) in CeCoIn5 with magnetic fields applied parallel (H) to antinodal [100] and nodal [110] directions. For H is [100], a single VL orientation observed, while 90° reorientation transition found for [110]. both field orientations configurations we find distorted hexagonal an anisotropy, Γ=2.0±0.05. The form factor shows strong Pauli paramagnetic effects similar what have previously been reported [001]. At high fields,...
In search of a quantum phase transition between the two-dimensional ($2$D) ferromagnetism CaCo$_{2-y}$As$_{2}$ and stripe-type antiferromagnetism in SrCo$_{2}$As$_{2}$, we rather find evidence for $1$D magnetic frustration square Co layers. We present neutron diffraction data Ca$_{1-x}$Sr$_{x}$Co$_{2-y}$As$_{2}$ that reveal sequence $x$-dependent transitions which involve different stacking $2$D ferromagnetically-aligned layers with anisotropy. explain changes to order by utilizing classical...
We present studies of the magnetic field distribution around vortices in ${\text{LuNi}}_{2}{\text{B}}_{2}\text{C}$. Small-angle neutron scattering measurements vortex lattice (VL) this material were extended to unprecedentedly large values vector $q$, obtained both by using high fields decrease VL spacing and higher order reflections. A square VL, oriented with nearest-neighbor direction along crystalline [110] direction, was observed up highest measured field. The first-order form factor,...
This aim of this study was to determine if a less resource-intensive and established offline correction protocol - the No Action Level (NAL) as effective daily online corrections setup deviations in curative high-dose radiotherapy prostate cancer.A total 683 megavoltage CT (MVCT) or kilovoltage (kvCBCT) images 30 patients with localized cancer treated intensity modulated were evaluated. Daily image-guidance performed errors three translational axes recorded. The NAL simulated by using mean...