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Results for "J. W. Lu"

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Line of magnetic monopoles and an extension of the Aharonov-Bohm effectJan 01 2016Feb 10 2016In the Landau problem on the two-dimensional plane, magnetic translation of a quantum wave can be induced by an in-plane electric field. The geometric phase accompanying such magnetic translation around a closed path differs from the topological phase ... More
Superconducting single-electron transistor coupled to a two dimensional electron gas: Transmission lines, dissipation, and charge averagingMay 17 2002We have developed a novel system consisting of a superconducting single-electron transistor (S-SET) coupled to a two-dimensional electron gas (2DEG), for which the dissipation can be tuned in the immediate vicinity of the S-SET. To analyze our results, ... More
Search For Non-Standard Model CP/T violation At Tau-Charm FactorySep 02 1996We systematically investigate the possibility of finding CP/T violation in the $\tau$ sector at Tau-Charm Factory. CP/T violation may occur at $\tau$ pair production process, expressed as electric dipole moment, and at $tau$ decay processes. By assuming ... More
On the Existence of Undistorted Progressive Waves (UPWs) of Arbitrary Speeds $0 \leq v< \infty$ in NatureJun 12 1996Oct 16 1997We present the theory, the experimental evidence, and fundamental physical consequences concerning the existence of families of undistorted progressive waves (UPWs) of arbitrary speeds $0\leq v < \infty$, which are solutions of the homogeneous wave equation, ... More
Extrinsic Curvature Embedding DiagramsJan 05 2003Embedding diagrams have been used extensively to visualize the properties of curved space in Relativity. We introduce a new kind of embedding diagram based on the {\it extrinsic} curvature (instead of the intrinsic curvature). Such an extrinsic curvature ... More
Comparison of room-temperature multiferroics in Bi4Fe2TiO12 film and bulkAug 18 2006Oct 27 2006It is reported that both dielectricity and magnetism at room temperature have been appreciably improved in Bi4Fe2TiO12 film compared with that of Bi4Fe2TiO12 bulk. X-ray diffraction profiles reveal similar crystalline nature and random orientation of ... More
$B_{s,d} \to γγ$ Decay with the Fourth GenerationFeb 19 2003We calculate the branching ratios of $B_{s,d}\to \gamma \gamma$ decay in the sequential fourth generation model. We find that the theoretical values of the branching ratios, ${\rm BR}(B_{s}\to\gamma\gamma)$, including the contributions of $t'$, are much ... More
Alternative approach to all-angle negative refraction in two-dimensional photonic crystalsMar 27 2007Jun 22 2007We show that with an appropriate surface modification, a slab of photonic crystal can be made to allow wave transmission within the band gap. Furthermore, negative refraction and all-angle-negative-refraction (AANR) can be achieved by this surface modification ... More
Nanowire waveguide made from extremely anisotropic metamaterialsApr 28 2008Exact solutions are obtained for all the modes of wave propagation along an anisotropic cylindrical waveguide. Closed-form expressions for the energy flow on the waveguide are also derived. For extremely anisotropic waveguide where the transverse permittivity ... More
Refraction of Electromagnetic Energy for Wave Packets Incident on a Negative Index Medium is Always NegativeJun 02 2003We analyze refraction of electromagnetic wave packets on passing from an isotropic positive to an isotropic negative refractive index medium. We definitively show that in all cases the energy is always refracted negatively. For localized wave packets, ... More
Charge Transport Processes in a Superconducting Single-Electron Transistor Coupled to a Microstrip Transmission LineOct 04 2001We have investigated charge transport processes in a superconducting single-electron transistor (S-SET) fabricated in close proximity to a two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure. The macroscopic bonding pads of the S-SET ... More
Testing the Universal Structured Jet Models of Gamma-Ray Bursts by BATSE ObservationsApr 18 2005Assuming that the observed gamma-ray burst (GRB) rate as a function of redshift is proportional to a corrected star formation rate, we derive the empirical distribution of the viewing angles of long BATSE GRBs, $P^{\rm em}(\theta)$, and the distribution ... More
Gamma-Ray Burst Sequences in Hardness Ratio-Peak Energy PlaneApr 18 2005The narrowness of the distribution of the peak energy of $\nu F_{\nu}$ spectrum of gamma-ray bursts (GRBs) and the unification of GRB population are great puzzles yet to be solved. We investigate the two puzzles based on the global spectral behaviors ... More
Superconducting Single-Electron Transistor in a Locally Tunable Electromagnetic Environment: Dissipation and Charge FluctuationsApr 12 2002We have developed a novel system consisting of a superconducting single-electron transistor (S-SET) coupled to a two-dimensional electron gas (2DEG), for which the dissipation can be tuned in the immediate vicinity of the S-SET. Within linear response, ... More
Radial Trends in IMF-Sensitive Absorption Features in Two Early-Type Galaxies: Evidence for Abundance-Driven GradientsJun 25 2015Feb 01 2016Samples of early-type galaxies show a correlation between stellar velocity dispersion and the stellar initial mass function (IMF) as inferred from gravity-sensitive absorption lines in the galaxies' central regions. To search for spatial variations in ... More
Strain-induced enhancement of thermoelectric performance in a ZrS2 monolayerFeb 28 2016Mar 03 2016The increase of a thermoelectric material's figure of merit (ZT value) is limited by the interplay of the transport coefficients. Here we report the greatly enhanced thermoelectric performance of a ZrS2 monolayer by the biaxial tensile strain, due to ... More
Premelting of Al nonperfect (111) surfaceNov 19 2009Melting behaviors of aluminum (111) perfect/nonperfect surfaces, characterized by structure ordering parameter, have been investigated by classical molecular dynamics simulation with embedded atom method potential. Al (111) perfect surface has a superheating ... More
Kerr-Schild Structure and Harmonic 2-forms on (A)dS-Kerr-NUT MetricsMay 31 2007Jun 19 2007We demonstrate that the general (A)dS-Kerr-NUT solutions in D dimensions with ([D/2], [(D+1)/2]) signature admit [D/2] linearly-independent, mutually-orthogonal and affinely-parameterised null geodesic congruences. This enables us to write the metrics ... More
Structural relaxation and Jahn-Teller distortion of LaMnO3 (001) surfaceApr 23 2009We studied in detail the structural relaxation and Jahn-Teller distortion in LaMnO3 (001) surface of the orthorhombic phase by means of classical atomistic simulation. It is found that MnO2-terminated surface is more energetically favorable than LaO-terminated ... More
Control of the magnon-photon level attraction in a planar cavityJan 22 2019A resistive coupling circuit is used to model the recently discovered dissipative coupling in a hybridized cavity photon-magnon system. With this model as a basis we have designed a planar cavity in which a controllable transition between level attraction ... More
Surface structure and solidification morphology of aluminum nanoclustersMay 09 2009Classical molecular dynamics simulation with embedded atom method potential had been performed to investigate the surface structure and solidification morphology of aluminum nanoclusters Aln (n = 256, 604, 1220 and 2048). It is found that Al cluster surfaces ... More
Agent Inspired Trading Using Recurrent Reinforcement Learning and LSTM Neural NetworksJul 23 2017With the breakthrough of computational power and deep neural networks, many areas that we haven't explore with various techniques that was researched rigorously in past is feasible. In this paper, we will walk through possible concepts to achieve robo-like ... More
Enhancing the thermoelectric performance of a HfS2 monolayer through valley engineeringAug 19 2016The electronic, phonon, and thermoelectric properties of a two-dimensional HfS2 monolayer are investigated by using the first-principles calculations combined with the Boltzmann transport theory. The band valleys of the HfS2 monolayer can be effectively ... More
Giant magnetoelectric effect under high bias fields in cylindrical bilayered Ni-PZT compositesAug 31 2007For conventional plate and disc layered magnetoelectric (ME) composites, the ME effect appeared under low bias magnetic fields, which caused by line magnetostriction. In this paper, we present a new structure ME composites, cylindrical bilayered composites. ... More
Room-temperature delayed giant magnetodielectric effects observed in Bi4Fe2TiO12 filmJun 30 2006Jan 22 2013This letter reports our experimental results on magnetic-field-induced aftereffects in solution derived Bi4Fe2TiO12 film, in which e' decreases as much as 600 times after treated in a 5T magnetic field as that of the pristine one. The phenomena are explained ... More
Prediction of superconductivity of $3d$ transition-metal based antiperovskites via magnetic phase diagramNov 18 2013Nov 22 2013We theoretically studied the electronic structure, magnetic properties, and lattice dynamics of a series of $3d$ transition-metal antiperovskite compounds AXM$_{3}$ by density function theory. Based on the Stoner criterion, we drew the magnetic phase ... More
Thermodynamic consistency, quark mass scaling, and properties of strange matterMay 13 2014The previous thermodynamic treatment for models with density and/or temperature dependent quark masses is shown to be inconsistent with the requirement of fundamental thermodynamics. We therefore study a fully self-consistent one according to the fundamental ... More
Coexistence of superconductivity and charge-density-wave domain in $1T$-Fe$_x$Ta$_{1-x}$SSeJun 20 2014Jun 23 2014A series of $1T$-Fe$_x$Ta$_{1-x}$SSe (0 $\leq x \leq$ 0.1) single crystals was fabricated via the chemical-vapor-transport (CVT) method and investigated by structure, transport, and magnetic measurements along with the density-functional-theory (DFT) ... More
Early-time spectroscopic observations of SN 1998aq in NGC 3982Mar 09 1999Medium resolution spectroscopic observations of SN 1998aq made in April-May, 1998, are presented. We confirm its Type Ia classification based on the prominent Si II 6355 A line and other features similar to SNe Ia. No significant sign of hydrogen Balmer-alpha ... More
Magnetodielectric effect of Bi6Fe2Ti3O18 film under an ultra-low magnetic fieldFeb 20 2006Feb 21 2006Good quality and fine grain Bi6Fe2Ti3O18 magnetic ferroelectric films with single-phase layered perovskite structure have been successfully prepared via metal organic decomposition (MOD) method. Results of low-temperature magnetocapacitance measurements ... More
Giant Magnetocaloric Effect in Re-entrant Ferromagnet PrMn1.4Fe0.6Ge2Aug 20 2008Sep 01 2008Three first order magnetic phase transitions (FOMT) have been detected at TCPr, TNinter and TCinter over the temperature range from 5 K to 340 K at fields up to 9 T in PrMn1.4Fe0.6Ge2, and the magnetocaloric effect (MCE) around these transitions evaluated. ... More
Radial Velocity Studies of Close Binary Stars.VIJan 14 2002May 29 2002Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented for the sixth set of ten close binary systems: SV Cam, EE Cet, KR Com, V410 Cyg, GM Dra, V972 Her, ET Leo, FS Leo, V2388 Oph, II UMa. All systems except ... More
Shape demagnetization effect on layered magnetoelectric compositesAug 30 2007Magnetoelectric (ME) voltage coefficient was always considered independent on in-plane shape of plate layered magnetostrictive-piezoelectric composites due to the oversimplification in ME theoretical models. In this article, we present that in fact the ... More
$λφ^4$ model and Higgs mass in standard model calculated by Gaussian effective potential approach with a new regularization-renormalization methodJan 12 1998Basing on new regularization-renormalization method, the $\lambda\phi^4$ model used in standard model is studied both perturbatively and nonperturbatively (by Gaussian effective potential). The invariant property of two mass scales is stressed and the ... More
Manipulating charge-density-wave in monolayer $1T$-TiSe$_2$ by strain and charge doping: A first-principles investigationJun 20 2017We investigate the effects of the in-plane biaxial strain and charge doping on the charge density wave (CDW) order of monolayer $1T$-TiSe$_2$ by using the first-principles calculations. Our results show that the tensile strain can significantly enhance ... More
Greenberger-Horne-Zeilinger-type violation of local realism by mixed statesMay 12 2008May 23 2008Cluster states are multi-particle entangled states with special entanglement properties particularly suitable for quantum computation. It has been shown that cluster states can exhibit Greenberger-Horne-Zeilinger (GHZ)-type non-locality even when some ... More
Nano-engineering of electron correlation in oxide superlatticesMar 14 2019Oxide heterostructures and superlattices have attracted a great deal of attention in recent years owing to the rich exotic properties encountered at their interfaces. We focus on the potential of tunable correlated oxides by investigating the spectral ... More
X-ray emission from HESS J1731-347/SNR G353.6-0.7 and Central Compact Source XMMS J173203-344518Jul 10 2009Jan 06 2010We present new results of the HESS J1731-347/SNR G353.6-0.7 system from XMM-NEWTOM and Suzaku X-ray observations, and Delinha CO observations. We discover extended hard X-rays coincident with the bright, extended TeV source HESS J1731-347 and the shell ... More
A GRB Follow-up System at the Xinglong Observatory and Detection of the High-Redshift GRB 060927Jun 16 2009A gamma-ray burst (GRB) optical photometric follow-up system at the Xinglong Observatory of National Astronomical Observatories of China (NAOC) has been constructed. It uses the 0.8-m Tsinghua-NAOC Telescope (TNT) and the 1-m EST telescope, and can automatically ... More
Entanglement-Enhanced Classical Communication over a Noisy Classical ChannelOct 13 2010Mar 31 2011We present and experimentally demonstrate a communication protocol that employs shared entanglement to reduce errors when sending a bit over a particular noisy classical channel. Specifically, it is shown that, given a single use of this channel, one ... More
Extracting CP violation and strong phase in D decays by using quantum correlations in psi(3770)-> D0\bar{D}0 -> (V1V2)(V3V4) and psi(3770)->D0\bar{D}0 -> (V1V2)(K pi)Dec 04 2009Apr 04 2010The charm quark offers interesting opportunities to cross-check the mechanism of CP violation precisely tested in the strange and beauty sectors. In this paper, we exploit the angular and quantum correlations in the D\bar{D} pairs produced through the ... More
Soliton solution of continuum magnetization-equation in conducting ferromagnet with a spin-polarized currentJun 04 2005Exact soliton solutions of a modified Landau-Lifshitz equation for the magnetization of conducting ferromagnet in the presence of a spin-polarized current are obtained by means of inverse scattering transformation. From the analytical solution effects ... More
Exact soliton solution and inelastic two-soliton collision in spin chain driven by a time-dependent magnetic fieldJun 04 2005We investigate dynamics of exact N-soliton trains in spin chain driven by a time-dependent magnetic field by means of an inverse scattering transformation. The one-soliton solution indicates obviously the spin precession around the magnetic field and ... More
Resolved Calabi-Yau Cones and Flows from L^{abc} Superconformal Field TheoriesJan 09 2007May 28 2007We discuss D3-branes on cohomogeneity-three resolved Calabi-Yau cones over L^{abc} spaces, for which a 2-cycle or 4-cycle has been blown up. In terms of the dual quiver gauge theory, this corresponds to motion along the non-mesonic, or baryonic, directions ... More
Si nanoparticle interfaces in Si/SiO2 solar cell materialsJun 09 2011Novel solar cell materials consisting of Si nanoparticles embedded in SiO2 layers have been studied using positron annihilation spectroscopy in Doppler broadening mode, and photoluminescence. Two positron-trapping interface states are observed after high ... More
Enhanced thermoelectric performance of phosphorene by strain-induced band convergenceJun 20 2014The newly emerging monolayer phosphorene was recently predicted to be a promising thermoelectric material. In this work, we propose to further enhance the thermoelectric performance of phosphorene by the strain-induced band convergence. The effect of ... More
Strain-controlled switch between ferromagnetism and antiferromagnetism in 1T-CrX2 (X = Se, Te) monolayersSep 25 2015Oct 20 2015We report on the strain-induced switch between ferromagnetic (FM) and antiferromagnetic (AFM) orderings in 1T-CrX2 (X = Se, Te) monolayers based on the first-principles calculations. The CrSe2 and CrTe2 monolayers without strains are found to be AFM and ... More
Electron-doped phosphorene: A potential monolayer superconductorMay 01 2014Dec 18 2014We predict by first-principles calculations that the electron-doped phosphorene is a potential BCS-like superconductor. The stretching modes at the Brillouin-zone center are remarkably softened by the electron-doping, which results in the strong electron-phonon ... More
Efficient and accurate treatment of electron correlations from first-principlesJun 30 2014We present an efficient \textit{ab initio} method for calculating the electronic structure and total energy of strongly correlated electron systems. The method extends the traditional Gutzwiller approximation for one-particle operators to the evaluation ... More
The Complete Cohomology of the W3 StringSep 07 1993We present a simple procedure for constructing the complete cohomology of the BRST operator of the two-scalar and multi-scalar $W_3$ strings. The method consists of obtaining two level--15 physical operators in the two-scalar $W_3$ string that are invertible, ... More
Aspects of N=2 Super-W_n StringsMay 15 1992We construct $N=2$ super-$W_{n+1}$ strings and obtain the complete physical spectrum, for arbitrary $n \ge 2$. We also derive more general realisations of the super-$W_{n+1}$ algebras in terms of $k$ commuting $N=2$ super energy-momentum tensors and $n-k$ ... More
Relationship between the gamma-ray burst pulse width and energy due to the Doppler effect of fireballsNov 13 2004Jul 01 2005We study in details how the pulse width of gamma-ray bursts is related with energy under the assumption that the sources concerned are in the stage of fireballs. Due to the Doppler effect of fireballs, there exists a power law relationship between the ... More
Effect of Native Defects on Optical Properties of InxGa1-xN AlloysAug 05 2005The energy position of the optical absorption edge and the free carrier populations in InxGa1-xN ternary alloys can be controlled using high energy 4He+ irradiation. The blue shift of the absorption edge after irradiation in In-rich material (x > 0.34) ... More
Self-compensation in highly n-type InNApr 15 2012Acceptor-type defects in highly n-type InN are probed using positron annihilation spectroscopy. Results are compared to Hall effect measurements and calculated electron mobilities. Based on this, self-compensation in n-type InN is studied and the microscopic ... More
A new mechanism for negative refraction and focusing using selective diffraction from surface corrugationFeb 12 2007Refraction at a smooth interface is accompanied by momentum transfer normal to the interface. We show that corrugating an initially smooth, totally reflecting, non-metallic interface provides a momentum kick parallel to the surface, which can be used ... More
Negative Refraction and Left-handed electromagnetism in Microwave Photonic CrystalsJun 04 2003Apr 05 2004We demonstrate negative refraction of microwaves in metallic photonic crystals. The spectral response of the photonic crystal, which manifests both positive and negative refraction, is in complete agreement with band-structure calculations and numerical ... More
Shared Representational Geometry Across Neural NetworksNov 28 2018Different neural networks trained on the same dataset often learn similar input-output mappings with very different weights. Is there some correspondence between these neural network solutions? For linear networks, it has been shown that different instances ... More
Anomaly Freedom and Realisations for Super-$W_3$ StringsNov 01 1991We construct new multi-field realisations of the $N=2$ super-$W_3$ algebra, which are important for building super-$W_3$ string theories. We derive the structure of the ghost vacuum for such theories, and use the result to calculate the intercepts. These ... More
Shared Representational Geometry Across Neural NetworksNov 28 2018Mar 16 2019Different neural networks trained on the same dataset often learn similar input-output mappings with very different weights. Is there some correspondence between these neural network solutions? For linear networks, it has been shown that different instances ... More
Temperature dependence of single-particle properties in nuclear matterJul 21 2008The single-nucleon potential in hot nuclear matter is investigated in the framework of the Brueckner theory by adopting the realistic Argonne V18 or Nijmegen 93 two-body nucleon-nucleon interaction supplemented by a microscopic three-body force. The rearrangement ... More
Robust method to determine the resolution of a superlens by analyzing the near-field image of a two-slit objectMay 01 2011In the last decade, metamaterials-based superlenses, with a resolution below Abbe's diffraction limit, have emerged. To obtain a rough estimate of the resolution of such superlenses, imaging of two subwavelength slits, separated by a subwavelength gap ... More
Single Semiconductor Quantum Dots in Microcavities: Bright sources of indistinguishable PhotonsJan 31 2015In this chapter we will discuss the technology and experimental techniques to realize quantum dot (QD) single photon sources combining high outcoupling efficiencies and highest degrees of non-postselected photon indistinguishability. The system, which ... More
N=2 Superstrings with (1,2m) Spacetime SignatureDec 06 1991We show that the $N=2$ superstring in $d=2D\ge6$ real dimensions, with criticality achieved by including background charges in the two real time directions, exhibits a ``coordinate-freezing'' phenomenon, whereby the momentum in one of the two time directions ... More
$N=1$ Superstring in $2+2$ DimensionsApr 24 1995In this paper we construct a $(2,2)$ dimensional string theory with manifest $N=1$ spacetime supersymmetry. We use Berkovits' approach of augmenting the spacetime supercoordinates by the conjugate momenta for the fermionic variables. The worldsheet symmetry ... More
An analysis of photoemission and inverse photoemission spectra of Si(111) and sulphur-passivated InP(001) surfacesMay 01 1997Photoemission (PES) and inverse-photoemission spectra (IPES) for the sulphur-passivated InP(001) surface are compared with theoretical predictions based on density-functional calculations. As a test case for our methods, we also present a corresponding ... More
Core-level spectroscopy of Si/SiO_2 quantum wells: evidence for confined statesAug 27 2002We present an experimental and theoretical study of the conduction states of crystalline Si films confined within amorphous SiO_2 barriers, using the Si-2p core-level excitations. The spectral peaks near the conduction band minimum are compared with the ... More
Isospin Dependence of 1S0 Proton and Neutron Superfluidity in Asymmetric Nuclear MatterAug 01 2006Oct 27 2006We investigate the $^1S_0$ neutron and proton superfluidity in isospin asymmetric nuclear matter. We have concentrated on the isospin dependence of the pairing gaps and the effect of a microscopic three-body force. It is found that as the isospin asymmetry ... More
Superlens imaging theory for anisotropic nanostructured metamaterials with broadband all-angle negative refractionOct 25 2007We show that a metamaterial consisting of aligned metallic nanowires in a dielectric matrix has strongly anisotropic optical properties. For filling ratio f<1/2, the composite medium shows two surface plasmon resonances (SPRs): the transverse and longitudinal ... More
Sinai billiards, Ruelle zeta-functions and Ruelle resonances: microwave experimentsJun 19 2002We discuss the impact of recent developments in the theory of chaotic dynamical systems, particularly the results of Sinai and Ruelle, on microwave experiments designed to study quantum chaos. The properties of closed Sinai billiard microwave cavities ... More
A Note on Einstein Sasaki Metrics in D \ge 7Nov 23 2004In this paper, we obtain new non-singular Einstein-Sasaki spaces in dimensions D\ge 7. The local construction involves taking a circle bundle over a (D-1)-dimensional Einstein-Kahler metric that is itself constructed as a complex line bundle over a product ... More
Large thermoelectric power factors in black phosphorus and phosphoreneApr 21 2014The electronic properties of the layered black phosphorus (black-P) and its monolayer counterpart phosphorene are investigated by using the first-principles calculations based on the density functional theory (DFT). The room-temperature electronic transport ... More
Geometrical structure effect on localization length of carbon nanotubesDec 20 2004Aug 26 2005The localization length and density of states of carbon nanotubes are evaluated within the tight-binding approximation. By comparison with the corresponding results for the square lattice tubes, it is found that the hexagonal structure affects strongly ... More
Pressure Effect on the superconducting properties of LaO_{1-x}F_{x}FeAs(x=0.11) superconductorMar 29 2008Apr 25 2008Diamagnetic susceptibility measurements under high hydrostatic pressure (up to 1.03 GPa) were carried out on the newly discovered Fe-based superconductor LaO_{1-x}F_{x}FeAs(x=0.11). The transition temperature T_c, defined as the point at the maximum slope ... More
A Superstring Theory in 2+2 DimensionsOct 03 1994In this paper we construct a $(2,2)$ dimensional string theory with manifest $N=1$ spacetime supersymmetry. We use Berkovits' approach of augmenting the spacetime supercoordinates by the conjugate momenta for the fermionic variables. The worldsheet symmetry ... More
Quantising Higher-spin String TheoriesOct 03 1994In this paper, we examine the conditions under which a higher-spin string theory can be quantised. The quantisability is crucially dependent on the way in which the matter currents are realised at the classical level. In particular, we construct classical ... More
Unconventional Scaling of the Anomalous Hall Effect Accompanying Electron Localization Correction in the Dirty RegimeOct 11 2012Scaling of the anomalous Hall conductivity to longitudinal conductivity, has been observed in the dirty regime of two-dimensional weak and strong localization regions in ultrathin, polycrystalline, chemically disordered, ferromagnetic FePt films. The ... More
Quantum Oscillations at Integer and Fractional Landau Level Indices in ZrTe5Feb 22 2016Mar 06 2016A three-dimensional (3D) Dirac semimetal (DS) is an analogue of graphene, but with linear energy dispersion in all (three) momentum directions.3D DSs have been a fertile playground in discovering novel quantum particles, for example Weyl fermions, in ... More
Generating multi-GeV electron bunches using single stage laser wakefield acceleration in a 3D nonlinear regimeDec 22 2006The extraordinary ability of space-charge waves in plasmas to accelerate charged particles at gradients that are orders of magnitude greater than in current accelerators has been well documented. We develop a phenomenological framework for Laser WakeField ... More
Two-Dimensional Node-Line Semimetals in a Honeycomb-Kagome LatticeMar 15 2016Recently, the concept of topological insulators has been generalized to topological semimetals, including three-dimensional (3D) Weyl semimetals, 3D Dirac semimetals, and 3D node-line semimetals. In particular, several compounds (e.g., certain three-dimensional ... More
X-ray Phase-Resolved Spectroscopy of PSRs B0531+21, B1509-58, and B0540-69 with RXTEApr 10 2012The Rossi X-ray Timing Explorer ({\sl RXTE}) has made hundreds of observations on three famous young pulsars (PSRs) B0531+21 (Crab), B1509-58, and B0540-69. Using the archive {\sl RXTE} data, we have studied the phase-resolved spectral properties of these ... More
Slow light, open cavity formation, and large longitudinal electric field on slab waveguide made of indefinite permittivity materialsFeb 25 2009Jan 07 2010The optical properties of slab waveguides made of indefinite permittivity ($\vep$) materials (IEM) are considered. In this medium the transverse permittivity is negative while the longitudinal permittivity is positive. At any given frequency the waveguide ... More
Raman spectroscopy at the edges of multilayer grapheneDec 27 2014Edges naturally exist in a single-layer graphene sample. Similarly, individual graphene layers in a multilayer graphene sample contribute their own edges. We study the Raman spectrum at the edge of a graphene layer laid on n layer graphene (nLG). We found ... More
Oxygen Abundance Determination in Very Metal-Deficient Giants: Permitted O I Lines Versus Forbidden [O I] LinesJul 02 2000The abundance of oxygen was determined for selected very metal-poor G-K stars (six giants and one turn-off star) based on the high S/N and high-resolution spectra observed with Keck HIRES in the red through near-IR region comprising the permitted O I ... More
Coherent control of magnon radiative damping with local photon statesFeb 18 2019The collective excitation of ordered spins, known as spin waves or magnons, can in principle radiate by emitting travelling photons to an open system when decaying to the ground state. However, in contrast to the electric dipoles, magnetic dipoles contributed ... More
Staged laser acceleration of high quality protons from a tailored plasmaSep 20 2018A new scheme of proton acceleration from a laser-driven near-critical-density plasma is proposed. Plasma with a tailored density profile allows a two-stage acceleration of protons. The protons are pre-accelerated in the laser-driven wakefields, and are ... More
Correlations among the Riemann zeros: Invariance, resurgence, prophecy and self-dualityMay 25 2004Jun 02 2004We present a conjecture describing new long range correlations among the Riemann zeros leading to 3 principal features: (i) The spectral auto-correlation is invariant w.r.t. the averaging window. (ii) Resurgence occurs wherein the lowest zeros appear ... More
1S0 Proton and Neutron Superfluidity in beta-stable Neutron Star MatterMar 10 2004We investigate the effect of a microscopic three-body force on the proton and neutron superfluidity in the $^1S_0$ channel in $\beta$-stable neutron star matter. It is found that the three-body force has only a small effect on the neutron $^1S_0$ pairing ... More
Flat lens without optical axis: Theory of imagingJan 28 2005Dec 15 2005We derive a general theory for imaging by a flat lens without optical axis. We show that the condition for imaging requires a material having elliptic dispersion relations with negative group refraction, equivalent to an effective anisotropic refractive ... More
Observation of a Logarithmic Temperature Dependence of Thermoelectric Power on Multiwall Carbon NanotubesFeb 05 2002We have investigated the thermoelectric power (TEP) of millimeter-long aligned multiwall carbon nanotubes down to a temperature of $T$=1.5 K, and observed for the first time an accurate $T {\rm ln} T$ dependence at low temperatures. This behavior is possibly ... More
The origin of the turn-on phenomenon in Td-MoTe2Jul 09 2017We did the resistivity and scanning tunneling microscope/spectroscopy (STM/STS) experiments at different temperatures and magnetic fields to investigate the origin of the turn-on (t-o) phenomenon of Td-MoTe2. There are two interesting observations. Firstly, ... More
Elastic Properties of Carbon Nanotubes and NanoropesApr 27 1997Elastic properties of carbon nanotubes and nanoropes are investigated using an empirical force-constant model. For single and multi-wall nanotubes the elastic moduli are shown to be insensitive to details of the structure such as the helicity, the tube ... More
Enhanced superconductivity by strain and carrier-doping in borophene: A first principles predictionApr 22 2016We predict by first principles calculations that the recently prepared borophene is a pristine two-dimensional (2D) monolayer superconductor, in which the superconductivity can be significantly enhanced by strain and charge carrier doping. The intrinsic ... More
Inversion symmetry breaking induced triply degenerate points in orderly arranged PtSeTe family materialsMar 03 2018$k$ paths exactly with $C_{3v}$ symmetry allow to find triply degenerate points (TDPs) in band structures. The paths that host the type-II Dirac points in PtSe$_2$ family materials also have the $C_{3v}$ spatial symmetry. However, due to Kramers degeneracy ... More
Spin photocurrent, its spectra dependence, and current-induced spin polarization in an InGaAs/InAlAs two-dimensional electron gasApr 13 2006Converse effect of spin photocurrent and current induced spin polarization are experimentally demonstrated in the same two-dimensional electron gas system with Rashba spin splitting. Their consistency with the strength of the Rashba coupling as measured ... More
Influence of temperature on the strain rate sensitivity and deformation mechanisms of nanotwinned CuMay 12 2018The mechanical behavior of nanotwinned Cu was studied through indentation creep and constant strain rate indentation tests from 25 $^\circ$C to 200 $^\circ$C. The results showed an enhanced strain rate sensitivity of nanotwinned Cu with temperature, which ... More
Galaxy Ecosystems: gas contents, inflows and outflowsAug 12 2014Mar 31 2015We use a set of observational data for galaxy cold gas mass fraction and gas phase metallicity to constrain the content, inflow and outflow of gas in central galaxies hosted by halos with masses between $10^{11} M_{\odot}$ to $10^{12} M_{\odot}$. The ... More
Gas and Metal Contents of Galaxies and Gaseous Halos: Preventive versus Ejective FeedbackApr 08 2015Using a semi-analytical approach we investigate the characteristics of predictions for the masses and metallicities of the baryonic matter in and around galaxies made by three galaxy formation models. These models represent three different feedback scenarios: ... More
Resonant soft x-ray emission as a bulk probe of correlated electron behavior in metallic Sr$_x$Ca$_{1-x}$VO$_3$Jul 24 2013The evolution of electron correlation in Sr$_{x}$Ca$_{1-x}$VO$_3$ has been studied using a combination of bulk-sensitive resonant soft x-ray emission spectroscopy (RXES), surface-sensitive photoemission spectroscopy (PES), and ab initio band structure ... More
Helical and skyrmion lattice phases in three-dimensional chiral magnets: Effect of anisotropic interactionsJun 27 2017In this work, we study the magnetic orders of the classical spin model with the anisotropic exchange and Dzyaloshinskii-Moriya interactions in order to understand the uniaxial stress effect in chiral magnets such as MnSi. Variational zero temperature ... More