A5050462236- 2D Materials and Applications
- Chalcogenide Semiconductor Thin Films
- MXene and MAX Phase Materials
- Graphene research and applications
- Perovskite Materials and Applications
- Advanced Condensed Matter Physics
- Organic and Molecular Conductors Research
- Physics of Superconductivity and Magnetism
- Diamond and Carbon-based Materials Research
- Solid-state spectroscopy and crystallography
- Particle Detector Development and Performance
- Iron-based superconductors research
- Magnetism in coordination complexes
- Topological Materials and Phenomena
- Crystal Structures and Properties
- Nuclear physics research studies
- Advanced Thermoelectric Materials and Devices
- Electron and X-Ray Spectroscopy Techniques
- Electronic and Structural Properties of Oxides
- Semiconductor materials and interfaces
- Photocathodes and Microchannel Plates
- High-pressure geophysics and materials
- Inorganic Chemistry and Materials
- Nuclear Physics and Applications
- Dark Matter and Cosmic Phenomena
Physical Measurement Laboratory
2017-2021
National Institute of Standards and Technology
2017-2021
Pennsylvania State University
2014-2020
DEVCOM Army Research Laboratory
2015-2017
University of Pittsburgh
2015-2017
Thomas Jefferson National Accelerator Facility
2012
We report the first measurement of parity-violating asymmetry APV in elastic scattering polarized electrons from Pb208. is sensitive to radius neutron distribution (Rn). The result APV=0.656±0.060(stat)±0.014(syst) ppm corresponds a difference between radii and proton distributions Rn−Rp=0.33−0.18+0.16 fm provides electroweak observation skin which expected heavy, neutron-rich nucleus.Received 12 January 2012DOI:https://doi.org/10.1103/PhysRevLett.108.112502© 2012 American Physical Society
The rise of two-dimensional (2D) materials research took place following the isolation graphene in 2004. These new 2D include transition metal dichalcogenides, mono-elemental sheets, and several carbide- nitride-based materials. number publications related to these emerging has been drastically increasing over last five years. Thus, through this comprehensive review, we aim discuss most recent groundbreaking discoveries as well opportunities remaining challenges. This review starts out by...
Defects play a significant role in tailoring the optical properties of two-dimensional materials. Optical signatures defect-bound excitons are important tools to probe defective regions and thus interrogate quality as-grown semiconducting monolayer We have performed systematic study using photoluminescence (PL) spectroscopy combined with atomically resolved scanning electron microscopy first-principles calculations. Spatially PL at low temperatures revealed bound that were present only on...
We report the fabrication of a photosensor based on as-grown single crystal monolayers MoS2 synthesized by chemical vapor deposition (CVD). The measurements were performed using Au/Ti leads in two terminal configuration CVD-grown SiO2/Si substrate. device was operated air at room temperature low bias voltages ranging from −2 V to 2 and its sensing capabilities tested for different excitation wavelengths (514.5 nm 488 nm). responsivity reached 1.1 mA W−1 when excited with 514.5 laser 1.5 V....
Significance The gas-sensing performance of graphene could be remarkably enhanced by incorporating dopants into its lattice based on theoretical calculations. However, to date, experimental progress boron-doped (BG) is still very scarce. Here, we achieved the controlled growth large-area, high-crystallinity BG sheets and shed light their electronic features associated with boron at atomic scale. As a proof-of-concept, it demonstrated that doping in lead much sensitivity when detecting toxic...
In ReS$_2$ a layer-independent direct band-gap of 1.5 eV implies potential for its use in optoelectronic applications. crystallizes the 1T$^{\prime}$-structure which leads to anisotropic physical properties and whose concomitant electronic structure might host non-trivial topology. Here, we report an overall evaluation Raman response transport few-layered field-effect transistors. We find that exfoliated on SiO$_2$ behaves as $n$-type semiconductor with intrinsic carrier mobility surpassing...
One of the most fascinating properties molybdenum disulfide (MoS2) is its ability to be subjected large amounts strain without experiencing degradation. The potential MoS2 mono- and few-layers in electronics, optoelectronics, flexible devices requires fundamental understanding their as a function strain. While previous reports have studied mechanically exfoliated flakes, tensile experiments on chemical vapor deposition (CVD)-grown few-layered not been examined hitherto, although CVD state...
Recently it was discovered that van der Waals bonded magnetic materials retain long range ordering down to a single layer, opening many avenues in fundamental physics and potential applications of these fascinating materials. One such material is $\mathrm{FeP}{\mathrm{S}}_{3}$, large spin $(S=2)$ Mott insulator where the Fe atoms form honeycomb lattice. In bulk, $\mathrm{FeP}{\mathrm{S}}_{3}$ has been shown be quasi-two-dimensional-Ising antiferromagnet, with additional features Raman...
The discovery of 2-dimensional (2D) materials, such as CrI3, that retain magnetic ordering at monolayer thickness has resulted in a surge both pure and applied research 2D magnetism. Here, we report magneto-Raman spectroscopy study on multilayered focusing two additional features the spectra appear below temperature were previously assigned to high frequency magnons. Instead, conclude these modes are actually zone-folded phonons. We observe striking evolution Raman with increasing field...
Strong hybridization of two-magnon scattering with phonons is observed in 2D antiferromagnet MnPSe 3 .
The strong in-plane anisotropy of rhenium disulfide (ReS2) offers an additional physical parameter that can be tuned for advanced applications such as logic circuits, thin-film polarizers, and polarization-sensitive photodetectors. ReS2 also presents advantages optoelectronics, it is both a direct-gap semiconductor few-layer thicknesses (unlike MoS2 or WS2) stable in air black phosphorus). Raman spectroscopy one the most powerful characterization techniques to nondestructively sensitively...
Abstract The field of two-dimensional (2D) and layered materials continues to excite many researchers around the world who are eager advance innovate viable routes for large scale synthesis, doping integration monolayers development unique characterization approaches studying harnessing exotic properties that will enable novel device applications. There has been a interest in 2D beyond graphene, with particular emphasis on monoelemental (phosphorene, silicene, tellurene, etc. ), compounds...
The interest in two-dimensional and layered materials continues to expand, driven by the compelling properties of individual atomic layers that can be stacked and/or twisted into synthetic heterostructures. plethora electronic as well emergence many different quasiparticles, including plasmons, polaritons, trions excitons with large, tunable binding energies all controlled modulated through electrical means has given rise device applications. In addition, these exhibit both room-temperature...
Tests of the standard model particle physics rely on measurements with highly polarized electron beams. A new instrument achieves highest known precision for determining beam polarization low-energy (~1 GeV)
Polarization-resolved Raman spectroscopy was performed and analyzed from large, high-quality, monodomain single crystal of $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$, a proximate Kitaev quantum spin liquid. Spectra were collected with laser polarizations parallel perpendicular to the honeycomb plane. Pairs nearly degenerate phonons discovered show either fourfold or twofold polarization angle dependence in their intensity, thereby providing evidence definitively assign...
We fabricated ambipolar field-effect transistors (FETs) from multi-layered triclinic ReSe2, mechanically exfoliated onto a SiO2 layer grown on p-doped Si. In contrast to previous reports thin layers (~2 3 layers), we extract carrier mobilities in excess of 102 cm2/Vs at room temperature crystals with nearly ~10 atomic layers. These thicker FETs also show zero threshold gate voltage for conduction and high ON OFF current ratios when compared the built thinner demonstrate that it is possible...
We have performed a novel comparison between electron-beam polarimeters based on Møller and Compton scattering. A sequence of polarization measurements were at low beam currents (<5μA) during the Qweak experiment in Hall-C Jefferson Lab. These current bracketed by regular high (180μA) operation polarimeter. All found to be consistent within experimental uncertainties 1% or less, demonstrating that electron does not depend significantly current. This result lends confidence common practice...
The Jefferson Lab Q_weak experiment determined the weak charge of proton by measuring parity-violating elastic scattering asymmetry longitudinally polarized electrons from an unpolarized liquid hydrogen target at small momentum transfer. A custom apparatus was designed for this to meet technical challenges presented smallest and most precise ${\vec{e}}$p ever measured. Technical milestones were achieved in power, beam current, helicity reversal rate, polarimetry, detected rates, control...
Magnetic excitations in van der Waals (vdW) materials, especially the two-dimensional (2D) limit, are an exciting research topic from both fundamental and applied perspectives. Using temperature-dependent, magneto-Raman spectroscopy, we identify hybridization of two-magnon with two separate E$_\mathrm{g}$ phonons MnPSe$_3$, a magnetic vdW material that could potentially host 2D antiferromagnetism. Results first principles calculations phonon magnon spectra further support our identification....