A5014864937- Magnetic and transport properties of perovskites and related materials
- Advanced Polymer Synthesis and Characterization
- Advanced Condensed Matter Physics
- Lipid Membrane Structure and Behavior
- Liquid Crystal Research Advancements
- Magnetic properties of thin films
- Magnetic Properties of Alloys
- Electronic and Structural Properties of Oxides
- Polymer Surface Interaction Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Materials and Mechanics
- High-pressure geophysics and materials
- Nanopore and Nanochannel Transport Studies
- Block Copolymer Self-Assembly
- Spectroscopy and Quantum Chemical Studies
- Material Dynamics and Properties
- Phase Equilibria and Thermodynamics
- Polymer composites and self-healing
- Advanced Sensor and Energy Harvesting Materials
- Additive Manufacturing and 3D Printing Technologies
- Iron-based superconductors research
- Electron and X-Ray Spectroscopy Techniques
- Magnetic Properties and Applications
- 3D Printing in Biomedical Research
- Tissue Engineering and Regenerative Medicine
Brookhaven National Laboratory
2016-2025
Los Alamos National Laboratory
2009-2025
National Synchrotron Light Source II
2020-2024
Université Paris-Saclay
2023
Stanford Synchrotron Radiation Lightsource
2020
Upton Hospital
2020
Argonne National Laboratory
2012-2013
West Virginia University
2011
Massachusetts Institute of Technology
2011
Center for Integrated Nanotechnologies
2011
The new alpha-Fe(Te,Se) superconductors share the common iron building block and ferminology with LaFeAsO BaFe(2)As(2) families of superconductors. In contrast predicted commensurate spin-density-wave order at nesting wave vector (pi, 0), a completely different magnetic composition tunable propagation (deltapi, deltapi) was determined for parent compound Fe_{1+y}Te in this powder single-crystal neutron diffraction study. antiferromagnetic survives as short-range one even highest T_{C}...
We have structurally characterized the liquid crystal (LC) phase that can appear as an intermediate state when a dielectric nematic, having polar disorder of its molecular dipoles, transitions to almost perfectly polar-ordered ferroelectric nematic. This phase, which fills 100-y-old void in taxonomy smectic LCs and we term "smectic ZA," is antiferroelectric, with nematic director polarization oriented parallel layer planes, alternating sign from 180 Å period. A Landau free energy, originally...
X-ray absorption spectroscopy studies of the magnetic-insulating ground state Sr2IrO4 at ambient pressure show a clear deviation from strong spin-orbit (SO) limit J(eff)=1/2 state, result local exchange interactions and nonzero tetragonal crystal field mixing SO split J(eff)=1/2, 3/2 states. magnetic circular dichroism measurements in diamond anvil cell transition ∼17 GPa, where "weak" ferromagnetic moment is quenched despite transport showing insulating behavior to least 40 GPa. The has...
We report the smectic $A_F$, a new liquid crystal phase of ferroelectric nematic realm. The $A_F$ is small polar, rod-shaped molecules which form two-dimensional fluid layers spaced by approximately mean molecular length. uniaxial, with director, local average long-axis orientation, normal to layer planes, and ferroelectric, spontaneous electric polarization parallel director. Polarization measurements indicate almost complete polar ordering $\sim 10$ Debye longitudinal dipoles, hysteretic...
Abstract We present a new ferroelectric nematic material, 4-((4′-((trans)-5-ethyloxan-2-yl)-2′,3,5,6′-tetrafluoro-[1,1′-biphenyl]-4-yl)difluoromethoxy)-2,6-difluorobenzonitrile (AUUQU-2-N) and its higher homologues, the molecular structures of which include fluorinated building blocks, an oxane ring, terminal cyano group, all contributing to large dipole moment about 12.5 D. observed that AUUQU-2-N has three distinct liquid crystal phases, two were found be polar phases with spontaneous...
Abstract The passive transport of molecules through a cell membrane relies on thermal motions the lipids. However, nature transmembrane and precise mechanism remain elusive call for comprehensive study phonon excitations. Here we report high resolution inelastic X-ray scattering in-plane excitations in 1,2-dipalmitoyl- sn -glycero-3-phosphocholine above below main transition temperature. In gel phase, first time, observe low-frequency transverse modes, which exhibit gap when lipid...
Bottlebrush molecules are branched polymers with a long linear backbone densely grafted by many relatively short side chains. Such unique molecular architecture enables bottlebrush properties and functions inaccessible their counterparts. The existing understanding is that, in melts of polymers, the interbackbone distance decreases as grafting density chains becomes smaller. Here, we experimentally discover behavior opposite to all works: increases monotonically decreases. To explain these...
Using polarized neutron reflectometry we measured the spin-dependent reflectivity from four LaAlO(3)/SrTiO(3) superlattices. Our results imply that upper limit for magnetization averaged over lateral dimensions of sample induced by an 11 T magnetic field at 1.7 K is less than 2 G. SQUID magnetometry superlattice samples sporadically finds enhanced moment, possibly due to experimental artifacts. These observations set important restrictions on theories which a strongly magnetism interface...
The effects of hydrogen (H2) and deuterium (D2) absorption were studied in two Co/Pd multilayers with perpendicular magnetic anisotropy (PMA) using polarized neutron reflectivity (PNR). PNR was measured an external field H applied the plane sample magnetization M confined for μ_o H= 6.0 T partially out at 0.65 T. Nominal thicknesses Co Pd layers 2.5 Å 21 Å, respectively. Because these small values, actual layer chemical composition, thickness, interface roughness parameters determined from...
In this work, we report on inelastic X-ray scattering experiments combined with the molecular dynamics simulations deeply supercritical Ar. The presented results unveil mechanism and regimes of sound propagation in liquid matter provide compelling evidence for adiabatic-to-isothermal longitudinal transition. We introduce a Hamiltonian predicting low-frequency transverse gaps, which is confirmed by experimental findings calculations. As result, universal link established between positive...
Using a specially designed apparatus, which collects simultaneous temperature and X-ray scattering data, we performed in situ measurements of the filament during MatEx 3D printing. The data show that printing extrusion process provides sufficient shear to form shish-kebab structures, initially nucleate at surface spread into core. Time-resolved kebab component near relaxes after deposition second enhances chain diffusion across interface. SEM images indicate complete interfacial merging...
Abstract Mantis shrimp are aggressive marine crustaceans well known for their rapid and powerful hunting strategies. Less known, however, is the ability of some species mantis to defend themselves from repeated blows conspecifics during ritualized fighting using a shield‐like segment abdominal armor called telson. Multiscale structure–mechanical property relationships this damage‐tolerant biological composite examined in order reveal strategies that nature uses resisting failure high‐energy...
Three-dimensional (3D) printing of elastomers enables the fabrication many technologically important structures and devices. However, there remains a critical need for development reprocessable, solvent-free, soft that can be printed without post-treatment. Herein, we report modular suitable direct ink writing (DIW) by physically cross-linking associative polymers with high fraction reversible bonds. We designed synthesized linear-associative-linear (LAL) triblock copolymers; middle block is...
Abstract The molecular foundations of epidermal cell wall mechanics are critical for understanding structure–function relationships primary walls in plants and facilitating the design bioinspired materials. To uncover mechanisms regulating high extensibility strength wall, onion is stretched uniaxially to various strains structures from mesoscale atomic scale characterized. Upon longitudinal stretching strain, contract transverse direction, resulting a reduced area. Atomic force microscopy...
Ambidirectionality, which is the ability of structural elements to move beyond a reference state in two opposite directions, common nature. However, conventional soft materials are typically limited single, unidirectional deformation unless complex hybrid constructs used. We exploited combination mesogen self-assembly, polymer chain elasticity, and polymerization-induced stress design liquid crystalline elastomers that exhibit mesophases: chevron smectic C (cSmC) A (SmA). Inducing...
Liquid crystal elastomers (LCEs) exhibit reversible shape morphing behavior when cycled above their nematic-to-isotropic transition temperature. During extrusion-based 3D printing, LCE inks are subjected to coupled shear and extensional flows that can be harnessed spatially control the alignment of nematic director along prescribed print paths. Here, we combine experiment modeling elucidate effects ink composition, nozzle geometry, printing parameters on alignment. From rheological...
Abstract Supercritical fluids play a significant role in elucidating fundamental aspects of liquid matter under extreme conditions. They have been extensively studied at pressures and temperatures relevant to various industrial applications. However, much less is known about the structural behaviour supercritical no crossovers observed static compression experiments any temperature pressure ranges beyond critical point. The structure state currently perceived be uniform everywhere on...
Here, we study structural properties of the supercritical carbon dioxide and discover existence persistent medium-range order correlations, which make nonuniform heterogeneous on an intermediate length scale. We report CO2 heterogeneity shell structure where, in first shell, both oxygen atoms experience gas-like-type interactions with short-range correlations while within second essentially exhibit a liquid-like type due to localization transverse-like phonon packets. Importantly, highlight...
In biological membranes, lipid rafts are now thought to be transient and nanoscopic. However, the mechanism responsible for these nanoscopic assemblies remains poorly understood, even in case of model membranes. As a result, it has proven extremely challenging probe physicochemical properties at molecular level. Here, we use all-atom dynamics (MD) simulations inelastic X-ray scattering (IXS), an intrinsically nanoscale technique, directly energy transfer collective short-wavelength (phonons)...
3D printing elastomers enables the fabrication of many technologically important structures and devices such as tissue scaffolds, sensors, actuators, soft robots. However, conventional printable are intrinsically stiff; moreover, process often requires external mechanical support and/or post-treatment. Here, we exploit self-assembly a responsive linear-bottlebrush-linear triblock copolymer to create stimuli-reversible, extremely soft, stretchable demonstrate their applicability inks for in...