Results for "L. J. Chen"

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Interaction driven surface Chern insulator in nodal line semimetalsJul 18 2018Jan 14 2019Nodal line semimetals are characterized by nontrivial bulk-band crossings, giving rise to almost flat drumhead-like surface states (DSS), which provide an attractive playground where interaction can induce symmetry-broken states and potential emergent ... More
On the Galactic Disk Metallicity Distribution from Open Clusters I. New Catalogues and Abundance GradientDec 26 2002In this paper we have compiled two new open cluster catalogues. In the first one, there are 119 objects with ages, distances and metallicities available, while in the second one, 144 objects have both absolute proper motion and radial velocity data, of ... More
Galactic metallicity distribution from open clustersOct 15 2003We have compiled two new Galactic open cluster catalogues. The first one has 119 objects with age, distance and metallicity data, while the second one has 144 objects with both absolute proper motion and radial velocity data, of which 45 clusters also ... More
Theory of Coherent Optical Control of Exciton Spin Dynamics in a Semiconductor Quantum DotSep 20 2000We use the spin-polarized excitons in a single quantum dot to design optical controls for basic operations in quantum computing. We examine the ultrafast nonlinear optical processes required and use the coherent nonlinear optical responses to deduce if ... More
Water bath calorimetric study of excess heat generation in 'resonant transfer' plasmasJan 26 2004Water bath calorimetry was used to demonstrate one more peculiar phenomenon associated with a certain class of mixed gas plasmas termed resonant transfer, or RT plasmas. Specifically, He/H2 (10%) (500 mTorr), Ar/H2 (10%) (500 mTorr), and H2O(g) (500 and ... More
Control of Spin Dynamics of Excitons in Nanodots for Quantum OperationsFeb 27 2001This work presents a step furthering a new perspective of proactive control of the spin-exciton dynamics in the quantum limit. Laser manipulation of spin-polarized optical excitations in a semiconductor nanodot is used to control the spin dynamics of ... More
Search for a $πΛN-πΣN$ dibaryon in p+p@3.5 GeVOct 29 2014This work is dedicated to the search for a $\pi\Lambda N\!-\!\pi\Sigma N$ resonance $\mathcal{Y}$ with the quantum numbers ($Y,I,J^P$) = (1,3/2,$2^+$). The double charged $\Sigma(1385)N\!-\!\Delta(1232)Y$ quasibound state was looked for in the reaction ... More
Frequency dependence of pulse width for 150 radio normal pulsarsJun 23 2014Nov 23 2014The frequency dependence of pulse width is studied for 150 normal pulsars, mostly selected from the European Pulsar Network, for which the 10\% multifrequency pulse widths can be well fit with the Thorsett relationship W_{10}=A\nu^{\mu}+W_{\rm 10, min}. ... More
Time Lags of Z Source GX 5-1Feb 25 2004We investigated the time lags and the evolution of the cross spectra of Z source GX~5-1, observed by the Rossi X-ray Timing Explorer (RXTE), when it is in the horizontal branch oscillations. We showed that the time lags of 3 horizontal branch oscillations ... More
Universal behavior of the upper critical field in iron based superconductorsJan 12 2012The newly discovered iron-based high temperature superconductors have demonstrated rich physical properties. Here we give a brief review on the recent studies of the upper critical field and its anisotropy in a few typical series of the iron-based superconductors ... More
Low Energy Proton-Deuteron Scattering in Configuration SpaceApr 20 2001Oct 12 2001A new method for solving the configuration-space Faddeev equations for elastic p-d scattering below the deuteron-breakup threshold is described. Numerical solutions that demonstrate the convergence and accuracy of the method are given. The number of channels ... More
Mass segregation in very young open clusters -- A case study of NGC 2244 and NGC 6530Jun 19 2007We derive the proper motions, membership probabilities, and velocity dispersions of stars in the regions of the young (about 2-4 Myr-old) open clusters NGC 2244 (the central cluster in the Monoceros R2 association) and NGC 6530 (the dominant cluster in ... More
A Cr-K emission line survey in young supernova remnants with ChandraOct 26 2008We performed a Cr-K emission line survey in young supernova remnants (SNRs) with the Chandra archival data. Our sample includes W49B, Cas A, Tycho and Kepler. We confirmed the existence of the Cr line in W49B and discovered this emission line in the other ... More
Evaluation of the 1077keV gamma-ray emission probability from 68Ga decaySep 30 201368Ga decays to the excited states of 68Zn through the electron capture decay mode. New recommended values for the emission probability of 1077keV gamma-ray given by the ENSDF and DDEP databases all use data from absolute measurements. In 2011 Jiang Liyang ... More
BCS-like superconductivity in the noncentrosymmetric compounds Nb$_x$Re$_{1-x}$Oct 31 2013We present research on the superconducting properties of Nb$_{x}$Re$_{1-x}$ ($x$ = 0.13-0.38) obtained by measuring the electrical resistivity $\rho(T)$, magnetic susceptibility $\chi(T)$, specific heat $C_P(T)$, and London penetration depth $\Delta\lambda(T)$. ... More
Evidence for two-gap superconductivity in the non-centrosymmetric compound LaNiC$_2$Aug 08 2012We study the superconducting properties of the non-centrosymmetric compound LaNiC$_2$ by measuring the London penetration depth $\Delta \lambda (T)$, the specific heat $C(T,B)$ and the electrical resistivity $\rho (T,B)$. Both $\Delta\lambda (T)$ and ... More
Open clusters: their kinematics and metellicitiesNov 16 2007We review our work on Galactic open clusters in recent years, and introduce our proposed large program for the LOCS (LAMOST Open Cluster Survey). First, based on the most complete open clusters sample with metallicity, age and distance data as well as ... More
Single crystal growth and physical property characterizations of mixed valent compound YbFe$_2$Al$_{10}$Dec 11 2016Jun 19 2017We report single crystal growth and physical properties characterization of YbFe$_2$Al$_{10}$ compounds. The measurements of resistivity, magnetic susceptibility, and specific heat show different behaviors from previous studies on polycrystal samples. ... More
Small-polaron hopping conductivity in bilayer manganite La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$Feb 19 2003We report anisotropic resistivity measurements on a La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$ single crystal over a temperature $T$ range from 2 to 400 K and in magnetic fields $H$ up to 14 T. For $T\geq 218$ K, the temperature dependence of the zero-field ... More
Low-temperature electrical transport in bilayer manganite La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$Mar 08 2002The temperature $T$ and magnetic field $H$ dependence of anisotropic in-plane $\rho_{ab}$ and out-of-plane $\rho_{c}$ resistivities have been investigated in single crystals of the bilayer manganite La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$. Below the Curie ... More
The 7-channel FIR HCN Interferometer on J-TEXT TokamakNov 24 2011Dec 28 2011A seven-channel far-infrared hydrogen cyanide (HCN) laser interferometer has been established aiming to provide the line integrated plasma density for the J-TEXT experimental scenarios. A continuous wave glow discharge HCN laser designed with a cavity ... More
Magnetotransport properties in purple bronze Li$_{0.9}$Mo$_6$O$_{17}$ Single CrystalJun 21 2009We have measured resistivity along the a, b and c axes of Li$_{0.9}$Mo$_6$O$_{17}$ single crystal. The anisotropy $\rho$$_c$ / $\rho$$_a$ and $\rho$$_c$ / $\rho$$_b$ is given, confirming the quasi-one-dimensionality of the compound. The sharp decrease ... More
Variable-range-hopping conductivity of half-doped bilayer manganite LaSr$_{2}$Mn$_{2}$O$_{7}$Jun 05 2003We report measurements of in-plane $\rho_{ab}$ and out-of-plane $\rho_{c}$ resistivities on a single crystal of the half-doped bilayer manganite LaSr$_{2}$Mn$_{2}$O$_{7}$. In the temperature $T$ range 220 to 300 K, the resistive anisotropy $\rho_{c}/\rho_{ab}=A+B/T$ ... More
Phenomenological study of light (anti)nuclei, (anti)hypertriton and di-Lambda production at RHICJun 21 2012Nov 07 2012We present the production of light (anti)nuclei, (anti)hypertriton and di-Lambda based on coalescence model in central Au+Au collisions at $\sqrt{s_{NN}}=200GeV$. The invariant yields of \He(\Hebar), \hypert(\hypertbar), \Hee(\Heebar) obtained is found ... More
NMR evidence of strong-correlated superconductivity in LiFeAs: tuning toward an SDW orderingAug 31 2010In this letter, we reported the results of NMR study on LiFeAs single crystals. We find a strong evidence of the low temperature spin fluctuations; by changing sample preparation conditions, the system can be tuned toward an spin-density-wave (SDW) quantum-critical ... More
Effects of magnetic dipole-dipole interactions in atomic Bose-Einstein condensates with tunable s-wave interactionsApr 06 2012Jul 23 2013The s-wave interaction is usually the dominant form of interactions in atomic Bose-Einstein condensates (BECs). Recently, Feshbach resonances have been employed to reduce the strength of the s-wave interaction in many atomic speicies. This opens the possibilities ... More
Theory of Fast Quantum Control of Exciton Dynamics in Semiconductor Quantum DotsSep 13 2001Optical techniques for the quantum control of the dynamics of multiexciton states in a semiconductor quantum dot are explored in theory. Composite bichromatic phase-locked pulses are shown to reduce the time of elementary quantum operations on excitons ... More
A Model for Radio Emission from Solar Coronal ShocksMar 20 2014Mar 23 2014Solar coronal shocks are very common phenomena in the solar atmosphere and are believed to be the drivers of solar type II radio bursts. However, the microphysical nature of these emissions is still an open problem. This paper proposes that electron cyclotron ... More
Strong Pinning Enhancement in MgB2 Using Very Small Dy2O3 AdditionsFeb 09 20060.5 to 5.0 wt.% Dy2O3 was in-situ reacted with Mg + B to form pinned MgB2. While Tc remained largely unchanged, Jc was strongly enhanced. The best sample (only 0.5 wt.% Dy2O3) had a Jc of 6.5 x 10^5 A/cm^2 at 6K, 1T and 3.5 x 10^5 A/cm^2 at 20K, 1T, around ... More
Novel dynamic scaling regime in hole-doped La2CuO4Jul 24 2003Only 3% hole doping by Li is sufficient to suppress the long-range 3-dimensional (3D) antiferromagnetic order in La2CuO4. The spin dynamics of such a 2D spin liquid state at T << J was investigated with measurements of the dynamic magnetic structure factor ... More
Half Heusler Alloys for Efficient Thermoelectric Power ConversionApr 19 2016Aug 04 2016Half-Heusler (HH) phases (space group F43m, Clb) are increasingly gaining attention as promising thermoelectric materials in view of their thermal stability, scalability, and environmental benignity as well as efficient power output. Until recently, the ... More
Infrared properties of $θ$-type ET charge-transfer salts: $θ$-ET$_2$CsZn(SCN)$_4$ vs $θ$-ET$_2$RbZn(SCN)$_4$Nov 12 2002We performed polarized far-infrared reflectance measurements at different temperatures on $\theta$-ET$_2$RbZn(SCN)$_4$ and $\theta$-ET$_2$CsZn(SCN)$_4$, two typical charge-transfer salts in a series of isostructural $\theta$-ET$_2$MM'(SCN)$_4$. The measurements ... More
Noise induced entanglementSep 29 2003We discuss the generation of entangled states of two two-level atoms coupled simultaneously with a dissipated atom. The dissipation of the atom is supposed to come from its coupling to a noise with adjustable intensity. We describe how the entanglement ... More
Optically controlled phase gate for two spin qubits in coupled quantum dotsNov 29 2011May 19 2015We present a feasible scheme for performing an optically controlled phase gate between two conduction electron spin qubits in adjacent self assembled quantum dots. Interaction between the dots is mediated by the tunneling of the valence hole state which ... More
A brief review of antimatter productionJan 21 2013In this article, we present a brief review of the discoveries of kinds of antimatter particles, including positron, antiproton, antideuteron and antihelium-3. Special emphasis is put on the discovery of the antihypertriton and antihelium-4 nucleus which ... More
Role of Starbursts in LINERsNov 25 1998We report our preliminary results on the role of starbursts in LINERs by use of WR galaxies as a tool. The essence of this approach lies in the different FIR-radio relation of WR galaxies from the pure AGN's.
Training a Multilingual Sportscaster: Using Perceptual Context to Learn LanguageJan 16 2014We present a novel framework for learning to interpret and generate language using only perceptual context as supervision. We demonstrate its capabilities by developing a system that learns to sportscast simulated robot soccer games in both English and ... More
A Blass-Sagan bijection on Eulerian equivalence classesJun 22 2007Following the treatment of Blass and Sagan, we present an algorithmic bijection between the Eulerian equivalence classes of totally cyclic orientations and the spanning trees without internal activity edges for a given graph.
Does Reactor Neutrino Experiment Play an Important Role in Theta_{13} of Lepton Mixing (PMNS) Matrix ?Sep 14 2004Sep 26 2004Reactor neutrinos play an important role in determining parameter theta_{13} in the lepton mixing (PMNS) matrix. A next important step on measuring PMNS matrix could be to build another reactor neutrino experiment, for example, DaYa bay in China, to search ... More
Grain Boundary Shear Coupling is Not a Grain Boundary PropertyOct 10 2018Shear coupling implies that all grain boundary (GB) migration necessarily creates mechanical stresses/strains and is a key component to the evolution of all polycrystalline microstructures. We present MD simulation data and theoretical analyses that demonstrate ... More
Optical RKKY Interaction between Charged Semiconductor Quantum DotsFeb 20 2002Jun 07 2002We show how a spin interaction between electrons localized in neighboring quantum dots can be induced and controlled optically. The coupling is generated via virtual excitation of delocalized excitons and provides an efficient coherent control of the ... More
Phase-Averaged Gamma-Ray Spectra from MSPsNov 04 2013{\it Fermi}-LAT has detected pulsed gamma-ray emissions with high confidences from more than 40 millisecond pulsars (MSPs). Here we study the phase-averaged gamma-ray properties of MSPs by using revised version of a self-consistent outer gap model. In ... More
Strong electron-Boson coupling effect in the infrared spectra of $Tl_2 Ba_2 Ca Cu_2 O_{8+δ}$Jun 27 2003We report on a study of the in-plane infrared response of a \TBCCO film with $T_c$=108 K. The fingerprint evidence for a strong electron-Boson coupling has been observed. The raw reflectance below T$_c$ exhibits a knee structure at around 650 \cm and ... More
Constraints on kHz QPO models and stellar EOSs from SAX J1808.4-3658, Cyg X-2 and 4U 1820-30Oct 15 2013We test the relativistic precession model (RPM) and the MHD Alfven wave oscillation model (AWOM) for the kHz QPOs by the sources with measured NS masses and twin kHz QPO frequencies. For RPM, the derived NS mass of Cyg X-2 (SAX J1808.4-3658 and 4U 1820-30) ... More
Searching for Classical Be Stars from the LAMOST DR1May 27 2015We report on searching for Classical B-type emission-line (CBe) stars from the first data release (DR1) of the Large Sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST; also named the Guoshoujing Telescope). A total of 192 (12 known CBes) objects ... More
Timescale Analysis of Spectral LagsJul 21 2004A technique for timescale analysis of spectral lags performed directly in the time domain is developed. Simulation studies are made to compare the time domain technique with the Fourier frequency analysis for spectral time lags. The time domain technique ... More
Ion-crystal demonstration of structural phase transition induced solely by temperatureDec 11 2018We demonstrate for the first time a linear-zigzag phase transition induced solely by temperature of the $^{40}$Ca$^{+}$ ion crystals in a surface-electrode trap. In contrast to the previously observed counterparts based on change of the mechanical equilibrium ... More
Upper critical field of the 122-type iron pnictide superconductorsJan 17 2011The upper critical fields ($H_{c2}$) of the single crystals $\rm(Sr,Na)Fe_2As_2$ and $\rm Ba_{0.55}K_{0.45}Fe_2As_2$ were determined by means of measuring the electrical resistivity, $ \rho_{xx}(\mu_0H)$, using the facilities of pulsed magnetic field ... More
Distribution of Spectral Lags in Gamma Ray BurstsOct 14 2004Oct 16 2004Using the data acquired in the Time To Spill (TTS) mode for long gamma-ray bursts (GRBs) collected by the Burst and Transient Source Experiment on board the Compton Gamma Ray Observatory (BATSE/CGRO), we have carefully measured spectral lags in time between ... More
Superfluidity and Phase Correlations of Driven Dissipative CondensatesJan 18 2016We review recent results on the coherence and superfluidity of driven dissipative condensates, i.e., systems of weakly-interacting non-conserved Bosons, such as polariton condensates. The presence of driving and dissipation has dramatically different ... More
Statistical properties of twin kHz QPO in neutron star LMXBsJan 23 2013Oct 21 2013We collect the data of twin kilohertz quasi-periodic oscillations (kHz QPOs) published before 2012 from 26 neutron star (NS) low-mass X-ray binary (LMXB) sources, then we analyze the centroid frequency (\nu) distribution of twin kHz QPOs (lower frequency ... More
Properties and Chemical Evolution of the M31 Disk: Comparison with the Milky WayJul 16 2008By adopting the chemical evolution model of the Milky Way disk, we have studied the star formation and chemical evolution history for M31 galaxy disk. We mainly concentrated on the global properties of the M31 disk. The model has been scaled to the related ... More
Effects of field-aligned flows on standing kink and sausage modes supported by coronal loopsSep 13 2013Sep 22 2013Fundamental standing modes and their overtones play an important role in coronal seismology. We examine how a significant field-aligned flow affects standing modes supported by coronal loops, modeled here as cold magnetic slabs. Of particular interest ... More
Does the Iron K$_α$ Line of Active Galactic Nuclei Arise from the Cerenkov Line-like Radiation?Sep 23 2003When thermal relativistic electrons with isotropic distribution of velocities move in a gas region, or impinge upon the surface of a cloud that consists of a dense gas or doped dusts, the Cerenkov effect produces peculiar atomic or ionic emission lines ... More
The Algorithm Z and Ramanujan's $_1ψ_1$ SummationNov 06 2009We use the Algortihm Z on partitions due to Zeilberger, in a variant form, to give a combinatorial proof of Ramanujan's $_1\psi_1$ summation formula.
New Multi-Scale Simulation Framework for Next-Generation Electronic Design Automation with Application to the Junctionless TransistorJul 13 2012In this paper we present a new multi-scale simulation scheme for next-generation electronic design automation for nano-electronics. The scheme features a combination of the first-principles quantum mechanical calculation, semi-classical semiconductor ... More
The analysis of Abell 1835 using a deprojection techniqueJun 14 2004We present the results from a detailed deprojection analysis of Abell 1835 as observed by {\it XMM-Newton}. If we fit the spectra with an isothermal plasma model, the deprojected temperature profile is flat in the outer region around 7.6 keV and decreases ... More
A proper motion study of the globular cluster M10Jun 09 2000We present the first proper motion study of M10 (NGC6254). Absolute proper motions of about 532 stars in the field of the globular cluster M10 were determined with respect to Hipparcos and ACT reference stars. In addition to photographic plates of Bonn ... More
On bounds of matrix eigenvaluesApr 13 2014In this paper, we give estimates for both upper and lower bounds of eigenvalues of a simple matrix. The estimates are shaper than the known results.
Refined physical properties and g',r',i',z',J,H,K transmission spectrum of WASP-23b from the groundMar 19 2013Multi-band observations of planetary transits using the telescope defocus technique may yield high-quality light curves suitable for refining the physical properties of exoplanets even with small or medium size telescopes. Such observations can be used ... More
Magnetotransport properties of the triply degenerate node topological semimetal tungsten carbideMar 09 2017May 31 2017We report the magnetoresistance (MR), Hall effect, and de Haas-van Alphen (dHvA) effect studies of the single crystals of tungsten carbide, WC, which is predicted to be a new type of topological semimetal with triply degenerate nodes. With the magnetic ... More
Magnetotransport properties of the new-type topological semimetal ZrTeJul 04 2017We report the first experimental results of the magnetoresistance, Hall effect, and quantum Shubnikov-de Haas oscillations on single crystals of ZrTe, which was recently predicted to be a new type of topological semimetal hosting both triply degenerate ... More
Investigation of the emission radii of kHz QPOs for the accreting millisecond X-Ray pulsars, Atoll and Z sourcesAug 29 2015We infer the emission positions of twin kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low mass X-ray binaries (NS-LMXBs) based on the Alfven wave oscillation model (AWOM). For most sources, the emission radii of kHz QPOs cluster around ... More
The magnetoresistance and Hall effect in CeFeAsO: a high magnetic field studyJan 17 2011The longitudinal electrical resistivity and the transverse Hall resistivity of CeFeAsO are simultaneously measured up to a magnetic field of 45T using the facilities of pulsed magnetic field at Los Alamos. Distinct behaviour is observed in both the magnetoresistance ... More
Morphological analysis on the coherence of kHz QPOsNov 23 2010Oct 31 2012We take the recently published data of twin kHz quasi-period oscillations (QPOs) in neutron star (NS) lowmass X-ray binaries (LMXBs) as the samples, and investigate the morphology of the samples, which focuses on the quality factor, peak frequency of ... More
Possible high temperature superconductivity in Ti-doped A-Sc-Fe-As-O (A= Ca, Sr) systemMar 30 2009Sep 17 2009We report a systematic study on the effect of partial substitution of Sc$^{3+}$ by Ti$^{4+}$ in Sr$_{2}$ScFeAsO$_{3}$, Ca$_{2}$ScFeAsO$_{3}$ and Sr$_{3}$Sc$_{2}$Fe$_{2}$As$_{2}$O$_{5}$ on their electrical properties. High level of doping results in an ... More
Infrared spectrum and its implications for the electronic structure of the semiconducting iron selenide K$_{0.83}$Fe$_{1.53}$Se$_2$Jan 03 2011Jun 16 2011We report an infrared spectroscopy study on K$_{0.83}$Fe$_{1.53}$Se$_2$, a semiconducting parent compound of the new iron-selenide system. The major spectral features are found to be distinctly different from all other Fe-based superconducting systems. ... More
An Evolutionary Timeline for High-mass Star FormationOct 08 2012The details of the physical process through which high-mass stars form remains nearly as much of a mystery now as it was when the Parkes radio telescope commenced operation. The energy output from high-mass stars influence, or directly drive many important ... More
The srank Conjecture on Schur's $Q$-FunctionsMay 19 2008We show that the shifted rank, or srank, of any partition $\lambda$ with distinct parts equals the lowest degree of the terms appearing in the expansion of Schur's $Q_{\lambda}$ function in terms of power sum symmetric functions. This gives an affirmative ... More
Improved Calculation of Thermal Fission EnergyDec 29 2012Jun 30 2013Thermal fission energy is one of the basic parameters needed in the calculation of antineutrino flux for reactor neutrino experiments. It is useful to improve the precision of the thermal fission energy calculation for current and future reactor neutrino ... More
Infrared properties of W-doped charge-density-wave material K$_{0.3}$MoO$_3$Nov 12 2002The optical conductivity spectra of quasi-one dimensional compounds K$_{0.3}$Mo$_{1-x}$W$_x$O$_3$ (x=0, 0.03 and 0.15) have been studied over broad frequencies. While the dc resistivity measurements indicate no sign of CDW transition in heavily W-doped ... More
Origin of the metallic to insulating transition of an epitaxial Bi(111) film grown on Si(111)May 12 2010May 20 2010Transport characteristics of single crystal bismuth films on Si(111)-7 \times 7 are found to be metallic or insulating at temperature below or above TC, respectively. The transition temperature TC decreases as the film thickness increases. By combining ... More
Observation of novel gapped phases in potassium doped single layer p-terphenyl on Au (111)May 28 2017Recently, superconductivity in potassium (K) doped p-terphenyl (C18H14) has been suggested by the possible observation of the Meissner effect and subsequent photoemission spectroscopy measurements, but the detailed lattice structure and more-direct evidence ... More
The mode switching of PSR B2020+28May 21 2016This paper reports on polarimetric radiation properties based on the switching modes of normal PSR B2020+28 by analysing the data acquired from the Nanshan 25-m radio telescope at 1556 MHz. With nearly 8 hours quasi-continuous observation, the data presented ... More
Probing the accretion disc structure by the twin kHz QPOs and spins of neutron stars in LMXBsJan 09 2017We analyze the relation between the emission radii of twin kilohertz quasi-periodic oscillations (kHz QPOs) and the co-rotation radii of the 12 neutron star low mass X-ray binaries (NS-LMXBs) which are simultaneously detected with the twin kHz QPOs and ... More
Two superconducting gaps in LaFeAsO0.92F0.08 revealed by 75As nuclear quadrupole resonanceOct 10 2008Dec 03 2008We report $^{75}$As nuclear quadrupole resonance (NQR) studies on superconducting oxypnictide LaFeAsO$_{0.92}$F$_{0.08}$ ($T_{\rm c}$ = 23 K). The temperature dependence of the spin lattice relaxation rate (1/$T_1$) decreases below $T_{\rm c}$ without ... More
First-order superfluid to Mott-insulator phase transitions in spinor condensatesDec 14 2015We observe evidence of first-order superfluid to Mott-insulator quantum phase transitions in a lattice-confined antiferromagnetic spinor Bose-Einstein condensate. The observed signatures include hysteresis effect and significant heatings across the phase ... More
Multiple phase transitions in single-crystalline Na$_{1-δ}$FeAsFeb 06 2009May 07 2009Specific heat, resistivity, susceptibility and Hall coefficient measurements were performed on high-quality single crystalline Na$_{1-\delta}$FeAs. This compound is found to undergo three successive phase transitions at around 52, 41, and 23 K, which ... More
Optical study on the spin-density wave properties in single crystalline Na$_{1-δ}$FeAsJul 01 2009We report an optical investigation on the in-plane charge dynamics for Na$_{1-\delta}$FeAs single crystal. A clear optical evidence for the spin-density wave (SDW) gap is observed. As the structural/magnetic transitions are separated in the Na$_{1-\delta}$FeAs ... More
Band-dependent Quasiparticle Dynamics in Single Crystals of the Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ Superconductor Revealed by Pump-Probe SpectroscopyMay 05 2009Jul 15 2010We report on band-dependent quasiparticle dynamics in Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ ($T_c = 37 K$) measured using ultrafast pump-probe spectroscopy. In the superconducting state, we observe two distinct relaxation processes: a fast component whose decay ... More
Rearrangement of Sodium ordering and its effect on physical properties in $Na_xCoO_2$ systemAug 31 2008We systematically study Raman spectroscopy of cleaved Na$_x$CoO$_2$ single crystals with 0.37 $\leq$ x $\leq$ 0.80. The Raman shift of A$_{1g}$ mode is found to be linearly dependent on Na content, while the Raman shift of E$_{1g}$ mode has an abnormal ... More
Tunable interplay between 3d and 4f electrons in Co-doped iron pnictidesDec 02 2012Mar 28 2013We study the interplay of 3d and 4f electrons in the iron pnictides CeFe$_{1-x}$Co$_x$AsO and GdFe$_{1-y}$Co$_y$AsO, which correspond to two very different cases of $4f$-magnetic moment. Both CeFeAsO and GdFeAsO undergo a spin-density-wave (SDW) transition ... More
Magnetic Order of the Iron Spins in NdOFeAsJul 04 2008Aug 22 2008Polarized and unpolarized neutron diffraction measurements have been carried out to investigate the iron magnetic order in undoped NdOFeAs. Antiferromagnetic order is observed below 141(6) K, which is in close proximity to the structural distortion observed ... More
Molecular-beam epitaxy of monolayer and bilayer WSe2: A scanning tunneling microscopy/spectroscopy study and deduction of exciton binding energyJun 15 2015Interests in two-dimensional transition-metal dichalcogenides have prompted some recent efforts to grow ultrathin layers of these materials epitaxially using molecular-beam epitaxy. However, growths of monolayer and bilayer WSe2, an important member of ... More
Effect of Strain on Ferroelectric Field Effect in Strongly Correlated Oxide Sm$_{0.5}$Nd$_{0.5}$NiO$_3$Sep 18 2015Oct 27 2015We report the effect of epitaxial strain on the magnitude and retention of the ferroelectric field effect in high quality PbZr$_{0.3}$Ti$_{0.7}$O$_3$ (PZT)/3.8-4.3 nm Sm$_{0.5}$Nd$_{0.5}$NiO$_3$ (SNNO) heterostructures grown on (001) LaAlO$_3$ (LAO) and ... More
Ferromagnetic resonance study of polycrystalline Cobalt ultrathin filmsSep 01 2005We present room temperature ferromagnetic resonance (FMR) studies of polycrystalline ||Pt/10 nm Cu/t Co/10 nm Cu/Pt|| films as a function of Co layer thickness (1 < t < 10 nm) grown by evaporation and magnetron sputtering. FMR was studied with a high ... More
Spin-torque driven ferromagnetic resonance of Co/Ni synthetic layers in spin valvesNov 02 2007Jan 07 2008Spin-torque driven ferromagnetic resonance (ST-FMR) is used to study thin Co/Ni synthetic layers with perpendicular anisotropy confined in spin-valve based nanojunctions. Field swept ST-FMR measurements were conducted with a magnetic field applied perpendicular ... More
Neutron Transversity at Jefferson LabNov 17 2005Nucleon transversity and single transverse spin asymmetries have been the recent focus of large efforts by both theorists and experimentalists. On-going and planned experiments from HERMES, COMPASS and RHIC are mostly on the proton or the deuteron. Presented ... More
Ewald summation for ferroelectric perovksites with charges and dipolesNov 24 2018Jan 10 2019Ewald summation is an important technique used to deal with long-range Coulomb interaction. While it is widely used in simulations of molecules and solid state materials, many important results are dispersed in literature and their implementations are ... More
Diffuse Neutron Scattering Study of Relaxor Ferroelectric (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3(PZN-xPT)Apr 16 2002Diffuse neutron scattering is a valuable tool to obtain information about the size and orientation of the polar nanoregions that are a characteristic feature of relaxor ferroelectrics. In this paper, we present new diffuse scattering results obtained ... More
Solving Solar Neutrino Puzzle via LMA MSW ConversionSep 19 2005We analyze the existing solar neutrino experiment data and show the allowed regions. The result from SNO's salt phase itself restricts quite a lot the allowed region's area. Reactor neutrinos play an important role in determining oscillation parameters. ... More
Electron Cyclotron Maser Emissions from Evolving Fast Electron BeamsMar 14 2016Fast electron beams (FEBs) are common products of solar active phenomena. Solar radio bursts are an important diagnostic tool in the understanding of FEBs as well as the solar plasma environment in which they are propagating along solar magnetic fields. ... More
Spin torque ferromagnetic resonance with magnetic field modulationOct 30 2013We demonstrate a technique of broadband spin torque ferromagnetic resonance (ST-FMR) with magnetic field modulation for measurements of spin wave properties in magnetic nanostructures. This technique gives great improvement in sensitivity over the conventional ... More
Coarse-graining renormalization by higher-order singular value decompositionJan 05 2012Aug 07 2012We propose a novel coarse graining tensor renormalization group method based on the higher-order singular value decomposition. This method provides an accurate but low computational cost technique for studying both classical and quantum lattice models ... More
Electronic Structure in Gapped Graphene with Coulomb PotentialApr 07 2008In this paper, we numerically study the bound electron states induced by long range Coulomb impurity in gapped graphene and the quasi-bound states in supercritical region based on the lattice model. We present a detailed comparison between our numerical ... More
Coherently photo-induced ferromagnetism in diluted magnetic semiconductorsDec 18 2003Ferromagnetism is predicted in undoped diluted magnetic semiconductors illuminated by intense sub-bandgap laser radiation . The mechanism for photo-induced ferromagnetism is coherence between conduction and valence bands induced by the light which leads ... More
A Study of the Water Cherenkov CalorimeterFeb 24 2006Mar 05 2006The novel idea of water Cherenkov calorimeter made of water tanks as the next generation neutrino detector for nu factories and nu beams is investigated. A water tank prototype with a dimension of 1*1*13m^3 is constructed, its performance is studied and ... More
Semantic Modelling with Long-Short-Term Memory for Information RetrievalDec 20 2014Feb 27 2015In this paper we address the following problem in web document and information retrieval (IR): How can we use long-term context information to gain better IR performance? Unlike common IR methods that use bag of words representation for queries and documents, ... More
Probing the IGM/Galaxy Connection IV: The LCO/WFCCD Galaxy Survey of 20 Fields Surrounding UV Bright QuasarsMar 09 2011We publish the survey for galaxies in 20 fields containing ultraviolet bright quasars (with z_em 0.1 to 0.5) that can be used to study the association between galaxies and absorption systems from the low-z intergalactic medium (IGM). The survey is magnitude ... More
Neutron Scattering Study of Relaxor Ferroelectric (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3Sep 18 2002Apr 02 2003Neutron elastic diffuse scattering experiments performed on Pb(Zn1/3Nb2/3)O3 (PZN) and on its solid solution with PbTiO3(PT), known as PZN-xPT, with x=4.5% and 9% around many reflections show that diffuse scattering is observed around reflections with ... More