Results for "H. -S. Chang"

total 205720took 0.14s
Particle Acceleration and Non-Thermal Emission in Pulsar Outer Magnetospheric GapJan 08 2008A two-dimensional electrodynamic model is used to study particle acceleration and non-thermal emission mechanisms in the pulsar magnetospheres. We solve distribution of the accelerating electric field with the emission process and the pair-creation process ... More
Cooperative single-photon subradiant statesMar 03 2016Jun 21 2016We propose a set of subradiant states which can be prepared and detected in a one-dimensional optical lattice. We find that the decay rates are highly dependent on the spatial phases imprinted on the atomic chain, which gives systematic investigations ... More
Even-odd behavior of conductance in monatomic sodium wiresAug 14 2001With the aid of the Friedel sum rule, we perform first-principles calculations of conductances through monatomic Na wires, taking into account the sharp tip geometry and discrete atomic structure of electrodes. We find that conductances (G) depend on ... More
Generalized Study with Isospin-phased Topological Approach on the $B \to Kπ$ PuzzleOct 25 2005May 02 2006We study the decay processes $B \to K \pi$ by using generalized decay amplitudes with both the final state re-scattering strong phases and the topological quark diagrammatic strong phases included together as part of fitting parameters. Using a generalized ... More
Semiconductor, topological semimetal, indirect semimetal, and topological Dirac semimetal phases of Ge$_{\text{1}-x}$Sn$_{x}$ alloysDec 01 2016Electronic structures of Ge$_{\text{1-$\textit x$}}$Sn$_{\text{$\textit x$}}$ alloys (0 $\leq$ $\textit x$ $\leq$ 1) are theoretically studied by nonlocal empirical pseudopotential method. For relaxed Ge$_{\text{1-$\textit x$}}$Sn$_{\text{$\textit x$}}$, ... More
Semiconductor, topological semimetal, indirect semimetal, and topological Dirac semimetal phases of Ge$_{1-x}$Sn$_{x}$ alloysDec 01 2016Feb 28 2017Electronic structures of Ge$_{1-x}$Sn$_{x}$ alloys (0 $\leq$ $x$ $\leq$ 1) are theoretically studied by nonlocal empirical pseudopotential method. For relaxed Ge$_{1-x}$Sn$_{x}$, a topological semimetal is found for $\textit x$ $>$ 41$\%$ with gapless ... More
Nonstandard Higgs DecaysAug 01 2008The crucial search for the Higgs boson at future colliders is capable of discovering the Standard Model Higgs, but is not guaranteed to discover a Higgs that decays nonstandardly. Such new physics is motivated by many aspects; from experiment, by the ... More
Signatures of the neutrino mass hierarchy in supernova neutrinosDec 16 2013Jun 17 2015The undetermined neutrino mass hierarchy may leave an observable imprint on the neutrino fluxes from a core-collapse supernova (SN). The interpretation of the observables, however, is subject to the uncertain SN models and the flavor conversion mechanism ... More
Eigenfrequency of nodeless elastic vibrations locked in the crust of quaking neutron starJan 28 2008Apr 01 2008The Newtonian solid-mechanical theory of non-compressional spheroidal and torsional nodeless elastic vibrations in the homogenous crust model of a quaking neutron star is developed and applied to the modal classification of the quasi-periodic oscillations ... More
Magnetic Quantum Dot: A Magnetic Transmission Barrier and ResonatorSep 07 2001We study the ballistic edge-channel transport in quantum wires with a magnetic quantum dot, which is formed by two different magnetic fields B^* and B_0 inside and outside the dot, respectively. We find that the electron states located near the dot and ... More
Exotic-Hadron Signature by Constituent-Counting Rule in Perturbative QCDNov 20 2016We explain a method to find internal quark configurations of exotic hadron candidates by using the constituent counting rule. The counting rule was theoretically predicted in perturbative QCD for hard exclusive hadron reactions, and it has been tested ... More
A two-dimensional electrodynamical outer gap model for gamma-ray pulsars: Gamma-ray spectrumNov 24 2005A two-dimensional electrodynamical model is used to study particle acceleration in the outer magnetosphere of a pulsar. The charge depletion from the Goldreich-Julian charge density causes a large electric field along the magnetic field lines. The charge ... More
Decay Process for Three - Species Reaction - Diffusion SystemDec 17 1999Dec 22 1999We propose the deterministic rate equation of three-species in the reaction - diffusion system. For this case, our purpose is to carry out the decay process in our three-species reaction-diffusion model of the form $A+B+C\to D$. The particle density and ... More
Polarization of high-energy emissions from the Crab pulsarOct 12 2006We investigate polarization of high-energy emissions from the Crab pulsar in the frame work of the outer gap accelerator, following previous works of Cheng and coworkers. The recent version of the outer gap, which extends from inside the null charge surface ... More
Power Law Distributions for Stock Prices in Financial MarketsDec 01 2004We study the rank distribution, the cumulative probability, and the probability density of returns of stock prices of listed firms traded in four stock markets. We find that the rank distribution and the cumulative probability of stock prices traded in ... More
Study on polarization of high-energy photons from the Crab pulsarJan 09 2007We investigate polarization of high-energy emissions from the Crab pulsar in the frame work of the outer gap accelerator. The recent version of the outer gap, which extends from inside the null charge surface to the light cylinder, is used for examining ... More
Dynamic communicability and epidemic spread: a case study on an empirical dynamic contact networkJan 27 2016Mar 13 2016We analyze a recently proposed temporal centrality measure applied to an empirical network based on person-to-person contacts in an emergency department of a busy urban hospital. We show that temporal centrality identifies a distinct set of top-spreaders ... More
Stabilizing the forming process in unipolar resistance switching using an improved compliance current limiterJun 26 2010The high reset current IR in unipolar resistance switching now poses major obstacles to practical applications in memory devices. In particular, the first IR-value after the forming process is so high that the capacitors sometimes do not exhibit reliable ... More
Towards unified understanding of conductance of stretched monatomic contactsNov 06 2003When monatomic contacts are stretched, their conductance behaves in qualitatively different ways depending on their constituent atomic elements. Under a single assumption of resonance formation, we show that various conductance behavior can be understood ... More
Nonlinear Phonon Interferometry at the Heisenberg LimitJan 11 2016Interferometers operating at or close to quantum limits of precision have found wide application in tabletop searches for physics beyond the standard model, the study of fundamental forces and symmetries of nature and foundational tests of quantum mechanics. ... More
Substrate-induced structures of bismuth adsorption on graphene: a first principle studyJul 28 2015Feb 23 2016The geometric and electronic properties of Bi-adsorbed monolayer graphene, enriched by the strong effect of substrate, are investigated by first-principles calculations. The six-layered substrate, corrugated buffer layer, and slightly deformed monolayer ... More
Predictability of reset switching voltages in unipolar resistance switchingMar 09 2009In unipolar resistance switching of NiO capacitors, Joule heating in the conducting channels should cause a strong nonlinearity in the low resistance state current-voltage (I-V) curves. Due to the percolating nature of the conducting channels, the reset ... More
Fundamental vibrational mode in a highly inhomogeneous starNov 17 2008Feb 10 2009The eigenfrequency problem of fundamental vibrational mode in a highly inhomogeneous star, modeled by self-gravitating mass of viscous liquid with singular density at the center, is considered in juxtaposition with that for Kelvin fundamental mode in ... More
Vacuum Condensates in the Global Color Symmetry ModelJun 25 1999Based on the quark propagator in the instanton dilute liquid approximation, we calculate analytically the quark condensate $<\bar{q}q>$, the mixed quark gluon condensate $g_{s}<\bar{q}G_{\mu\nu}\sigma^{\mu\nu}q>$ and the four quark condensate $<\bar{q} ... More
Reestablishing Kepler_s first two laws for planets from the non_stationary EarthNov 05 2014The Earth itself is not stationary but keeps revolving, and its motion further satisfies the law of equal area according to the heliocentric doctrine. That satisfaction can be used to construct the mathematical relationships between the planet_Sun and ... More
Baryon Chiral Perturbation Theory up to Next-to-Leading OrderDec 22 1994We examine the general lagrangian for baryon chiral perturbation theory with SU(3) flavor symmetry, up to the next-to-leading order. We consider both the strong and the weak interaction. The inverse of the baryon mass is treated as an additional small ... More
The Okubo relation for the baryon magnetic moments and chiral perturbation theoryFeb 06 1997Dec 30 1997We analyze the Okubo SU(3) relation among the hyperon magnetic moments in the usual scheme of chiral perturbation theory (ChPT). We classify the one-loop diagrams, including those with intermediate decuplet baryons, in a simple way according to whether ... More
Self-gravitating astrophysical mass with singular central density vibrating in fundamental modeMay 04 2009Dec 23 2009The fluid-dynamical model of a self-gravitating mass of viscous liquid with singular density at the center vibrating in fundamental mode is considered in juxtaposition with that for Kelvin fundamental mode in a homogeneous heavy mass of incompressible ... More
SU(3) breaking and baryon magnetic momentsFeb 08 1996Jan 15 1997We show that the magnetic moments of the octet baryons can be fitted to an accuracy of 1.5 percent by a phenomenological Lagrangian in which SU(3) breaking corrections appear only linearly. This is in contrast to conventional chiral perturbation theory ... More
Heavy-baryon chiral perturbation theory and reparametrization invarianceNov 07 1996We examine the constraints imposed by reparametrization invariance on heavy-baryon chiral perturbation theory (HBChPT). We study the case of 3 flavors and consider both the strong and weak ($|\Delta S| =1$) interaction sector. Some of the parameters in ... More
Hyperon weak radiative decays in chiral perturbation theoryJan 19 1996We investigate the leading-order amplitudes for weak radiative decays of hyperons in chiral perturbation theory. We consistently include contributions from the next-to-leading order weak-interaction Lagrangian. It is shown that due to these terms Hara's ... More
Frequency spectrum of toroidal Alfvén mode in a neutron star with Ferraro's form of nonhomogeneous poloidal magnetic fieldFeb 05 2009Jul 15 2009Using the energy variational method of magneto-solid-mechanical theory of a perfectly conducting elastic medium threaded by magnetic field, the frequency spectrum of Lorentz-force-driven global torsional nodeless vibrations of a neutron star with Ferraro's ... More
Spheroidal and torsional modes of quasistatic shear oscillations in the solid globe models of nuclear physics and pulsar astrophysicsApr 13 2007Aug 15 2007The past three decades of investigation on nuclear physics and pulsar astrophysics have seen gradual recognition that elastodynamic approach to the continuum mechanics of nuclear matter provides proper account of macroscopic motions of degenerate Fermi-matter ... More
The Phase-resolved High Energy Spectrum of the Crab PulsarApr 12 2007We present a modified outer gap model to study the phase-resolved spectra of the Crab pulsar. A theoretical double peak profile of the light curve containing the whole phase is shown to be consistent with the observed light curve of the Crab pulsar by ... More
Spin orders in the supersolid phases in binary Rydberg-dressed Bose-Einstein condensatesMay 23 2013We show that the five possible ordered states in a quantum spin-1/2 system with long-range exchange interactions: Neel, ladder, Peierls, coincidence, and domain states, can be realized in a binary Rydberg-dressed BEC system in the supersolid phase. In ... More
Elasticity of nuclear medium as a principal macrodynamical promoter of electric dipole pygmy resonanceApr 01 2008May 10 2008Motivated by arguments of the nuclear core-layer model formulated in [S.I. Bastrukov, J.A. Maruhn, Z.Phys. A 335 (1990) 139], the macroscopic excitation mechanism of electric pygmy dipole resonance (PDR) is considered as owing its origin to perturbation-induced ... More
Multifractal Measures on Small-World NetworksMay 06 2004May 07 2004We investigate the multifractals of the normalized first passage time on one-dimensional small-world network with both reflecting and absorbing barriers. The multifractals is estimated from the distribution of the normalized first passage time charactrized ... More
Scaling behaviors of RESET voltages and currents in unipolar resistance switchingOct 22 2008Unipolar switching phenomena have attracted a great deal of recent attention, but the wide distributions of switching voltages still pose major obstacles for scientific advancement and practical applications. Using NiO capacitors, we investigated the ... More
Initial stages of nickel oxide growth on Ag(001) by pulsed laser depositionJun 09 2009Sep 24 2010Submonolayers of nickel oxide films were grown on an Ag(001) by pulsed laser deposition, and characterized in-situ by both scanning tunneling microscopy and X-ray photoelectron spectroscopy. We observed quasi-two-dimensional growth of the film, and clearly ... More
Thermodynamic properties of tetrameric bond-alternating spin chainsDec 10 2004May 10 2005Thermodynamic properties of a tetrameric bond-alternating Heisenberg spin chain with ferromagnetic-ferromagnetic-antiferromagnetic-antiferromagnetic exchange interactions are studied using the transfer-matrix renormalization group and compared to experimental ... More
Radio Frequency Response of the Strongly Interacting Fermi Gases at Finite TemperaturesMay 13 2009Oct 06 2009The radio frequency spectrum of the fermions in the unitary limit at finite temperatures is characterized by the sum rule relations. We consider a simple picture where the atoms are removed by radio frequency excitations from the strongly interacting ... More
Complexity Induced Sporadic Localized Multifractal Antiscreening in Gravitational Evolution at Large ScalesAug 27 2015It has been suggested that antiscreening effects due to the running of the gravitational constant G might provide a partial solution to the dark matter mystery. It has also been hypothesized that renormalization group scaling transformations at large ... More
Coarse Obstructions to Positive Scalar Curvature Metrics in Noncompact Arithmetic ManifoldsMay 11 2000Block and Weinberger show that an arithmetic manifold can be endowed with a positive scalar curvature metric if and only if its $\rationals$-rank exceeds 2. We show in this article that these metrics are never in the same coarse class as the natural metric ... More
Fundamental thickness limit of itinerant ferromagnetic SrRuO$_3$ thin filmsMar 02 2009Jul 07 2009We report on a fundamental thickness limit of the itinerant ferromagnetic oxide SrRuO$_3$ that might arise from the orbital-selective quantum confinement effects. Experimentally, SrRuO$_3$ films remain metallic even for a thickness of 2 unit cells (uc), ... More
Neutron scattering investigation of the magnetic order in single crystalline BaFe2As2Jan 07 2009The magnetic structure of BaFe2As2 was completely determined from polycrystalline neutron diffraction measurements soon after the ThCr2Si2-type FeAs-based superconductors were discovered. Both the moment direction and the in-plane antiferromagnetic wavevector ... More
Equation of State and Phases of Polarized Unitary Fermi GasNov 28 2007Jun 02 2008The equation of state of the partially polarized two component Fermi gas at zero temperature in the unitary limit is computed by {\it ab initio} auxiliary field Monte Carlo method. We obtain the critical ratio of the chemical potentials $\mu_\downarrow/\mu_\uparrow$ ... More
Trapped Atoms in One-Dimensional Photonic CrystalsJan 22 2013We describe one-dimensional photonic crystals that support a guided mode suitable for atom trapping within a unit cell, as well as a second probe mode with strong atom-photon interactions. A new hybrid trap is analyzed that combines optical and Casimir-Polder ... More
CO-induced lifting of Au (001) surface reconstructionJan 21 2008We report CO-induced lifting of the hexagonal surface reconstruction on Au (001). Using in-situ surface x-ray scattering, we determined a pressure-temperature phase diagram for the reconstruction and measured the dynamical evolution of the surface structure ... More
Polarization spectroscopy of defect-based single photon sources in ZnOOct 21 2015Point-defects in wide bandgap semiconductors are promising candidates for future applications that necessitate quantum light sources. Recently, defect-based single photon sources have been observed in ZnO that are very bright and remain photoactive from ... More
Asteroseismic model of paramagnetic neutron starOct 16 2009Mar 01 2010We investigate an asteroseismic model of non-rotating paramagnetic neutron star with core-crust stratification of interior pervaded by homogeneous internal and dipolar external magnetic field, presuming that neutron degenerate Fermi-matter of the star ... More
Magnetic field induced enhancement of spin-order peak intensity in La(1.875)Ba(0.125)CuO(4)Oct 22 2008Dec 18 2008We report on neutron-scattering results on the impact of a magnetic field on stripe order in the cuprate La$_{1.875}$Ba$_{0.125}$CuO$_4$. It is found that a 7 T magnetic field applied along the {\it c} axis causes a small but finite enhancement of the ... More
High-fidelity and robust two-qubit gates for quantum-dot spin qubits in siliconJun 07 2018A two-qubit controlled-NOT (CNOT) gate, realized by a controlled-phase (C-phase) gate combined with single-qubit gates, has been experimentally implemented recently for quantum-dot spin qubits in isotopically enriched silicon, a promising solid-state ... More
Nodeless differentially rotational Alfvén oscillations of crustal solid-state plasma in quaking neutron starDec 24 2008Dec 28 2008The two-component, core-crust, model of a neutron star with homogenous internal and dipolar external magnetic field is studied responding to quake-induced perturbation by substantially nodeless differentially rotational Alfv\'en oscillations of the perfectly ... More
Surface X-ray Speckles: Coherent Surface Diffraction from Au (0 0 1)Sep 11 2009We present coherent speckled x-ray diffraction patterns obtained from a monolayer of surface atoms. We measured both the specular anti-Bragg reflection and the off-specular hexagonal reconstruction peak for the Au (0 0 1) surface reconstruction. We observed ... More
Zipf's Law Distributions for Korean Stock PricesMay 18 2004This paper investigates the rank distribution, cumulative probability, and probability density of price returns for the stocks traded in the KSE and the KOSDAQ market. This research demonstrates that the rank distribution is consistent approximately with ... More
Pressure-induced high temperature superconductivity in H3X (X=As, Se, Br, Sb, Te and I)Mar 08 2019The discovery of high critical temperature Tc superconductivity in highly compressed H3S has opened up the question of searching for strong electron-phonon coupling in the hydrides outside the transition metal series. In this work, we performed Linearized ... More
Chandra Observation of PWN G16.73+0.08 in SNR G16.7+0.1Nov 14 2017We present X-ray observations of PWN G16.73+0.08/SNR G16.7+0.1 using archival data of {\it Chandra} ACIS. The X-ray emission peak location of this pulsar wind nebula is found to be offset by 24 arcsec from the centre of the 1.4-GHz emission of this nebula. ... More
Torsional shear oscillations in the neutron star crust driven by restoring force of elastic stressesJul 12 2007Sep 04 2007We present several exact solutions of the eigenfrequency problem for torsional shear vibrations in homogeneous and non-homogeneous models of the neutron star crust governed by canonical equation of solid mechanics with a restoring force of Hookean elasticity. ... More
Surface response of spherical core-shell structured nanoparticle by optically induced elastic oscillations of soft shell against hard coreSep 24 2008Mar 13 2009The optically induced oscillatory response of a spherical two-component, shell-core structured, nanoparticle by nodeless elastic vibrations of soft peripheral shell against hard and dynamically immobile inner core is considered. The eigenfrequencies of ... More
Reaction-diffusion processes of three species on small-world networksMar 29 2005We study the decay process for the reaction-diffusion process of three species on the small-world network. The decay process is manipulated from the deterministic rate equation of three species in the reaction-diffusion system. The particle density and ... More
Dynamical Isometry and a Mean Field Theory of LSTMs and GRUsJan 25 2019Training recurrent neural networks (RNNs) on long sequence tasks is plagued with difficulties arising from the exponential explosion or vanishing of signals as they propagate forward or backward through the network. Many techniques have been proposed ... More
Strange superconductivity near an antiferromagnetic heavy fermion quantum critical pointJun 11 2018The heavy fermion CeMIn5 family with M = Co, Rh, Ir provide a prototypical example of strange superconductors with unconventional d-wave pairing and strange metal normal state, emerged near an antiferromagnetic quantum critical point. The microscopic ... More
Alfven seismic vibrations of crustal solid-state plasma in quaking paramagnetic neutron starNov 05 2010Nov 22 2010Magneto-solid-mechanical model of two-component, core-crust, paramagnetic neutron star responding to quake-induced perturbation by differentially rotational, torsional, oscillations of crustal electron-nuclear solid-state plasma about axis of magnetic ... More
Kinetics of natural aging in Al-Mg-Si alloys studied by positron annihilation lifetime spectroscopyJun 24 2010Jul 11 2012The process of natural aging in pure ternary Al-Mg-Si alloys was studied by positron annihilation lifetime spectroscopy in real time in order to clarify the sequence and kinetics of clustering and precipitation. It was found that natural aging takes place ... More
Conformal Field Theory of Composite FermionsMar 06 2006Jun 28 2006We show that the quantum Hall wave functions for the ground states in the Jain series can be exactly expressed in terms of correlation functions of local vertex operators, V_n, corresponding to composite fermions in the n:th composite-fermion (CF) Landau ... More
A single-molecule approach to ZnO defect studies: single photons and single defectsFeb 07 2014Investigations that probe defects one at a time offer a unique opportunity to observe properties and dynamics that are washed out of ensemble measurements. Here we present confocal fluorescence measurements of individual defects in Al-doped ZnO nanoparticles ... More
Torsional nodeless vibrations of quaking neutron star restored by combined forces of shear elastic and magnetic field stressesJun 15 2008Sep 18 2008Within the framework of Newtonian magneto-solid-mechanics, relying on equations appropriate for a perfectly conducting elastic continuous medium threaded by a uniform magnetic field, the asteroseismic model of a neutron star undergoing axisymmetric global ... More
Reduction of charge fluctuation energies in ultrathin NiO films on Ag(001)Jul 01 2011Jul 13 2011We investigate on-site Coulomb interaction energy between two 3p holes U(Ni 3p) of ultrathin NiO films on Ag(001) by both x-ray photoelectron spectroscopy and Auger electron spectroscopy. As the film becomes thin, U(Ni 3p) monotonically decreases, and ... More
Tidal Interaction as the origin of early-type dwarf galaxies in group environmentOct 29 2014We present a sample of dwarf galaxies that suffer ongoing disruption by the tidal force of nearby massive galaxies. Analysing structural and stellar population properties using the archival imaging and spectroscopic data from the Sloan Digital Sky Survey ... More
Non-thermal emissions from outer magnetospheric accelerators of middle-aged pulsarsOct 21 2008We discuss $\gamma$-ray emissions from the outer gap accelerators of middle-aged pulsars for part of the series of our studies. A two-dimensional electrodynamic model is used to solve the distribution of accelerating electric fields with electron and ... More
Pulse Profiles, Spectra and Polarization Characteristics of Non-Thermal Emissions from the Crab-Like PulsarsJul 23 2007We discuss non-thermal emission mechanism of the Crab-like pulsars with both a two-dimensional electrodynamical study and a three-dimensional model. We investigate the emission process in the outer gap accelerator. In the two-dimensional electrodynamical ... More
Links Between Z Sources and Atoll SourcesNov 01 2012It is known that the Z and atoll sources are two typical types of neutron-star sources in low mass X-ray binaries (LMXBs), which present very different Q-$\nu$ relations of lower kHz QPOs. We propose that the Z and atoll sources are two different phases ... More
Soft x-ray magnetic circular dichroism study on Gd-doped EuO thin filmsSep 28 2005We report on the growth and characterization of ferromagnetic Gd-doped EuO thin films. We prepared samples with Gd concentrations up to 11% by means of molecular beam epitaxy under distillation conditions, which allows a very precise control of the doping ... More
Quantum many-body models with cold atoms coupled to photonic crystalsDec 09 2013Nov 03 2015Using cold atoms to simulate strongly interacting quantum systems represents an exciting frontier of physics. However, as atoms are nominally neutral point particles, this limits the types of interactions that can be produced. We propose to use the powerful ... More
Thermal Conductivity of Graphene Laminate: Making Plastic Thermally ConductiveJul 05 2014We have investigated thermal conductivity of graphene laminate films deposited on polyethylene terephthalate substrates. Two types of graphene laminate were studied - as deposited and compressed - in order to determine the physical parameters affecting ... More
Reduction of high reset currents in unipolar resistance switching Pt/SrTiOx/Pt capacitors using acceptor dopingMar 06 2010The high reset current, IR, in unipolar resistance switching is an important issue which should be resolved for practical applications in nonvolatile memories. We showed that,during the forming and set processes, the compliance current, Icomp, can work ... More
Spin Correlations in the Geometrically Frustrated Pyrochlore Tb2Mo2O7Jul 14 2008We report neutron scattering studies of the spin correlations of the geometrically frustrated pyrochlore Tb2Mo2O7 using single crystal samples. This material undergoes a spin-freezing transition below Tg~24 K, similar to Y2Mo2O7, and has little apparent ... More
Ultraviolet photonic crystal laserJun 01 2004We fabricated two dimensional photonic crystal structures in zinc oxide films with focused ion beam etching. Lasing is realized in the near ultraviolet frequency at room temperature under optical pumping. From the measurement of lasing frequency and spatial ... More
Search of Axions from a Nuclear Power Reactor with a High-Purity Germanium DetectorSep 01 2006Jan 21 2007A search of axions produced in nuclear transitions was performed at the Kuo-Sheng Nuclear Power Station with a high-purity germanium detector of mass 1.06 kg at a distance of 28 m from the 2.9 GW reactor core. The expected experimental signatures were ... More
Retrograde wind accretion -- an alternative mechanism for long spin-period of SFXTsJul 05 2012Oct 23 2012A new class of high-mass X-ray binaries (HMXBs) --- supergiant fast X-ray transients (SFXTs) --- are discovered by INTEGRAL, which are associated with OB supergiants and present long spin periods. Observational evidence indicates that some accreting neutron ... More
Can SGRs/AXPs originate from neutron star binaries?Jan 21 2013Dec 09 2014Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are two groups of enigmatic objects, which have been extensively investigated in past few decades. Based on the ample information about their timing behaviors, spectra, and variability properties, ... More
Effect of pressure on the quantum spin ladder material IPA-CuCl3Sep 08 2008Inelastic neutron scattering and bulk magnetic susceptibility studies of the quantum S=1/2 spin ladder system IPA-CuCl3 are performed under hydrostatic pressure. The pressure dependence of the spin gap $\Delta$ is determined. At $P=1.5$ GPa it is reduced ... More
Strong resistance nonlinearity and third harmonic generation in the unipolar resistance switching of NiO thin filmsOct 06 2008We investigated third harmonic generation in NiO thin films, which exhibit unipolar resistance switching behavior. We found that the low resistance states of the films were strongly nonlinear, with variations in the resistance R as large as 60%. This ... More
Quarkonium-Nucleus Bound States from Lattice QCDOct 26 2014Aug 13 2015Quarkonium-nucleus systems are composed of two interacting hadronic states without common valence quarks, which interact primarily through multi-gluon exchanges, realizing a color van der Waals force. We present lattice QCD calculations of the interactions ... More
Layered-specific hole concentrations in Bi2Sr2(Y1-xCax)Cu2O8+d as probed by XANES spectroscopy and coulometric redox analysisFeb 24 2003Induction of holes not only in the superconductive CuO2 plane but also in the Bi2O2+d charge reservoir of the Bi2Sr2(Y1-xCax)Cu2O8+d superconductor upon CaII-for-YIII substitution is evidenced by means of two independent techniques, i.e., high-resolution ... More
Dispersive resonance bands within the space charge layer of metal- semiconductor junctionJun 03 2010Based on measurements of angle resolved photoemission, we report that in the Pb/Ge(111)- \sqrt{3}x\sqrt{3} R30^\circ structure, in addition to three bands resembling Ge heavy hole (HH), light hole (LH), and split off (SO) bulk band edges, a fourth dispersive ... More
Initial growth behavior and resulting microstructural properties of heteroepitaxial ZnO thin films on sapphire (0001) substratesAug 22 2006We have investigated the initial growth behavior and resulting microstructural properties of heteroepitaxial ZnO thin films prepared by pulsed laser deposition on sapphire (0001) substrates. High-resolution x-ray diffraction and transmission electron ... More
Magnetic structure of antiferromagnetic NdRhIn5Jun 19 2002The magnetic structure of antiferromagnetic NdRhIn5 has been determined using neutron diffraction. It has a commensurate antiferromagnetic structure with a magnetic wave vector (1/2,0,1/2) below T_N = 11K. The staggered Nd moment at 1.6K is 2.6mu_B aligned ... More
Properties of Microlensing Light Curve Anomalies Induced by Multiple PlanetsJul 27 2001In this paper, we show that the pattern of microlensing light curve anomalies induced by multiple planets are well described by the superposition of those of the single-planet systems where the individual planet-primary binary pairs act as independent ... More
Polyhedral Cosmic StringsJun 09 1992Quantum field theory is discussed in M\"obius corner kaleidoscopes using the method of images. The vacuum average of the stress-energy tensor of a free field is derived and is shown to be a simple sum of straight cosmic string expressions, the strings ... More
Spin states and persistent currents in mesoscopic rings: spin-orbit interactionsSep 07 2006Oct 12 2006We investigate theoretically electron spin states in one dimensional (1D) and two dimensional (2D) hard-wall mesoscopic rings in the presence of both the Rashba spin-orbit interaction (RSOI) and the Dresselhaus spin-orbit interaction (DSOI) in a perpendicular ... More
Spin states and persistent currents in a mesoscopic ring with an embedded magnetic impurityJun 26 2007Spin states and persistent currents are investigated theoretically in a mesoscopic ring with an embedded magnetic ion under a uniform magnetic field including the spin-orbit interactions. The magnetic impurity acts as a spin-dependent $\delta$-potential ... More
Vacuum energy on orbifold factors of spheresOct 02 1992The vacuum energy is calculated for a free, conformally-coupled scalar field on the orbifold space-time \R$\times \S^2/\Gamma$ where $\Gamma$ is a finite subgroup of O(3) acting with fixed points. The energy vanishes when $\Gamma$ is composed of pure ... More
Analytic torsion on spherical factors and tessellationsApr 06 2009May 05 2009The analytic torsion is computed on fixed-point free and non fixed-point free factors (tessellations) of the three--sphere. We repeat the standard computation on spherical space forms (Clifford-Klein spaces) by an improved technique. The transformation ... More
Surface electronic structure of a topological Kondo insulator candidate SmB6: insights from high-resolution ARPESJun 19 2013The Kondo insulator SmB6 has long been known to exhibit low temperature (T < 10K) transport anomaly and has recently attracted attention as a new topological insulator candidate. By combining low-temperature and high energy-momentum resolution of the ... More
T=0 Partition Functions for Potts Antiferromagnets on Lattice Strips with Fully Periodic Boundary ConditionsJul 29 2000We present exact calculations of the zero-temperature partition function for the $q$-state Potts antiferromagnet (equivalently, the chromatic polynomial) for families of arbitrarily long strip graphs of the square and triangular lattices with width $L_y=4$ ... More
On the Stability of Dust-Laden Protoplanetary VorticesJul 14 2010Aug 11 2010The formation of planetesimals via gravitational instability of the dust layer in a protoplanetary disks demands that there be local patches where dust is concentrated by a factor of $\sim$ a few $\times 10^3$ over the background value. Vortices in protoplanetary ... More
Atomic and electronic structure of a copper/graphene interface as prepared and 1.5 years afterJul 31 2017We report the results of X-ray spectroscopy and Raman measurements of as-prepared graphene on a high quality copper surface and the same materials after 1.5 years under different conditions (ambient and low humidity). The obtained results were compared ... More
Percolation Model Explaining Both Unipolar Memory and Threshold Resistance Switchings in NiO FilmMar 31 2008We observed two types of unipolar resistance switching (RS) in NiO film: memory RS at low temperature and threshold RS at high temperature. We explain these phenomena using a bond percolation model that describes the forming and rupturing of conducting ... More
Engineering One-Dimensional Quantum Stripes from Superlattices of Two-Dimensional Layered MaterialsOct 24 2016One-dimensional (1D) quantum systems, which are predicted to exhibit novel states of matter in theory, have been elusive in experiment. Here we report a superlattice method of creating artificial 1D quantum stripes, which offers dimensional tunability ... More