Results for "K. H. Wu"

total 166478took 0.25s
Relativistic light synthesis of femtosecond sawtooth pulsesSep 04 2018Formation of femtosecond sawtooth pulses by high harmonic generation from relativistic oscillating mirrors is studied. For oblique incidence of $p$-polarized laser pulse, one can efficiently control the intensity of the first few harmonics by modifying ... More
Topological Charge of Lattice Abelian Gauge TheoryJan 26 2000Configuration space of abelian gauge theory on a periodic lattice becomes topologically disconnected by excising exceptional gauge field configurations. It is possible to define a U(1) bundle from the nonexceptional link variables by a smooth interpolation ... More
Spin Excitation in d-wave Superconductors : A Fermi Liquid PictureJun 21 2000Jan 12 2001A detailed study of the Inelastic Neutron Scattering (INS) spectra of the high-$T_c$ cuprates based on the Fermi liquid (FL) picture is given. We focus on the issue of the transformation between the commensurate and incommensurate (IC) excitation driven ... More
Search for pulsed gamma-ray emission from globular cluster M28Feb 04 2013Using the data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope, we have searched for the gamma-ray pulsations from the direction of globular cluster M28 (NGC 6626). We report the discovery of a signal with the frequency consistent ... More
Orbital Phase Dependent Gamma-ray emissions from the Black Widow PulsarOct 26 2012We report on evidence for orbital phase-dependence of the gamma-ray emission from PSR B1957+20 black widow system by using the data of the Fermi Large Area Telescope. We divide an orbital cycle into two regions: a region containing the inferior conjunction, ... More
Discovery of γ-ray pulsation and X-ray emission from the black widow pulsar PSR J2051-0827Jan 28 2012We report the discovery of pulsed {\gamma}-ray emission and X-ray emission from the black widow millisecond pulsar PSR J2051-0827 by using the data from the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope and the Advanced CCD Imaging ... More
Discovery of gamma-ray emission from the supernova remnant Kes 17 with Fermi Large Area TelescopeAug 20 2011We report the discovery of GeV emission at the position of supernova remnant Kes 17 by using the data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Kes 17 can be clearly detected with a significance of ~12 sigma in the 1 ... More
Exploring the dark accelerator HESS J1745-303 with Fermi Large Area TelescopeApr 26 2011We present a detailed analysis of the gamma-ray emission from HESS J1745-303 with the data obtained by the Fermi Gamma-ray Space Telescope in the first ~29 months observation.The source can be clearly detected at the level of ~18-sigma and ~6-sigma in ... More
Reply to Comment on "Superfluid stability in the BEC-BCS crossover" by Sheehy and RadzihovskyAug 23 2006The reason behind the discrepancy between the phase diagrams of our earlier work [1] and the comment of Sheehy and Radzihovsky [2] is discussed. We show that, in contrast to what is claimed in [2], the requirement of positive susceptibility is sufficient ... More
Phase diagram of a dilute fermion gas with density imbalanceSep 27 2006We map out the phase diagram of a dilute two-component atomic fermion gas with unequal populations and masses under a Feshbach resonance. As in the case of equal masses, no uniform phase is stable for an intermediate coupling regime. For majority component ... More
Resonant pairing between Fermions with unequal massesApr 25 2006Aug 28 2006We study the pairing between Fermions of different masses, especially at the unitary limit. At equal populations, the thermodynamic properties are identical with the equal mass case provided an appropriate rescaling is made. At unequal populations, for ... More
Superfluid stability in BEC-BCS crossoverJun 17 2005We consider a dilute atomic gas of two species of fermions with unequal concentrations under a Feshbach resonance. We find that the system can have distinct properties due to the unbound fermions. The uniform state is stable only when either (a) beyond ... More
Analysis of Asymmetric Piezoelectric Composite BeamFeb 21 2008This paper deals with the vibration analysis of an asymmetric composite beam composed of glass a piezoelectric material. The Bernoulli's beam theory is adopted for mechanical deformations, and the electric potential field of the piezoelectric material ... More
Topological Obstruction in Block-spin TransformationsJun 06 2000Block-spin transformations from a fine lattice to a coarse one are shown to give rise to a one-to-one correspondence between the zero-modes of the Ginsparg-Wilson Dirac operators. The index is then preserved under the blocking process. Such a one-to-one ... More
Universal Extra Dimensions and b -> s gammaMay 09 2001Jun 26 2001We analyze the effect of flat universal extra dimensions (i.e., extra dimensions accessible to all SM fields) on the process b -> s gamma. With one Higgs doublet, the dominant contribution at one-loop is from Kaluza-Klein (KK) states of the charged would-be-Goldstone ... More
Charged Higgs decays in models with singlet neutrino in large extra dimensionsJun 12 2000Aug 04 2000In models with large extra dimensions and TeV scale quantum gravity, small (Dirac) neutrino masses can be obtained naturally if the right-handed neutrino propagates in the extra dimensions. In this scenario, with 2 Higgs doublets, we show that the decay ... More
Machine learning-guided directed evolution for protein engineeringNov 27 2018Apr 19 2019Machine learning (ML)-guided directed evolution is a new paradigm for biological design that enables optimization of complex functions. ML methods use data to predict how sequence maps to function without requiring a detailed model of the underlying physics ... More
Identification campaign of supernova remnant candidates in the Milky Way. II. X-ray studies of G38.7-1.4Mar 03 2014We report on XMM-Newton and Chandra observations of the Galactic supernova remnant candidate G38.7-1.4, together with complementary radio, infrared, and gamma-ray data. An approximately elliptical X-ray structure is found to be well correlated with radio ... More
Machine learning in protein engineeringNov 27 2018Machine learning-guided protein engineering is a new paradigm that enables the optimization of complex protein functions. Machine-learning methods use data to predict protein function without requiring a detailed model of the underlying physics or biological ... More
Asymptotic Performance Evaluation of Battery Swapping and Charging Station for Electric VehiclesJul 22 2017Jul 26 2017A battery swapping and charging station (BSCS) is an energy refueling station, where i) electric vehicles (EVs) with depleted batteries (DBs) can swap their DBs for fully-charged ones, and ii) the swapped DBs are then charged until they are fully-charged. ... More
Topological Phase Transition Independent of System Non-HermiticityMay 18 2019Non-Hermiticity can vary the topology of system, induce topological phase transition, and even invalidate the conventional bulk-boundary correspondence. Here, we show the introducing of non-Hermiticity without affecting the topological properties of the ... More
On Symplectic and Multisymplectic Srtuctures and their Discrete Versions in Lagrangian FormalismApr 06 2001Aug 13 2001We introduce the Euler-Lagrange cohomology to study the symplectic and multisymplectic structures and their preserving properties in finite and infinite dimensional Lagrangian systems respectively. We also explore their certain difference discrete counterparts ... More
Can extra dimensions accessible to the SM explain the recent measurement of anomalous magnetic moment of the muon?Mar 21 2001Apr 04 2001We investigate whether models with flat extra dimensions in which SM fields propagate can give a significant contribution to the anomalous magnetic moment of the muon (MMM). In models with only SM gauge and Higgs fields in the bulk, the contribution to ... More
The optimisation of low-acceleration interstellar relativistic rocket trajectories using genetic algorithmsJan 28 2017A vast wealth of literature exists on the topic of rocket trajectory optimisation, particularly in the area of interplanetary trajectories due to its relevance today. Studies on optimising interstellar and intergalactic trajectories are usually performed ... More
A Note on Symplectic AlgorithmsApr 06 2001Aug 09 2001We present the symplectic algorithm in the Lagrangian formalism for the Hamiltonian systems by virtue of the noncommutative differential calculus with respect to the discrete time and the Euler--Lagrange cohomological concepts. We also show that the trapezoidal ... More
Spectrally-accurate quadratures for evaluation of layer potentials close to the boundary for the 2D Stokes and Laplace equationsOct 08 2014Dense particulate flow simulations using integral equation methods demand accurate evaluation of Stokes layer potentials on arbitrarily close interfaces. In this paper, we generalize techniques for close evaluation of Laplace double-layer potentials in ... More
Asymmetric Fermi superfluid with different atomic species in a harmonic trapAug 23 2007We study the dilute fermion gas with pairing between two species and unequal concentrations in a harmonic trap using the mean field theory and the local density approximation. We found that the system can exhibit a superfluid shell structure sandwiched ... More
Exploring the X-ray and gamma-ray properties of the redback millisecond pulsar PSR J1723-2837Nov 01 2013Dec 24 2013We have investigated the X-ray and $\gamma$-ray properties of the redback millisecond pulsar PSR J1723-2837 with XMM-Newton, Chandra and Fermi. We have discovered the X-ray orbital modulation of this binary system with the minimum that coincides with ... 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
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
Symplectic, Multisymplectic Structures and Euler-Lagrange CohomologyApr 17 2001We study the Euler-Lagrange cohomology and explore the symplectic or multisymplectic geometry and their preserving properties in classical mechanism and classical field theory in Lagrangian and Hamiltonian formalism in each case respectively. By virtue ... More
Energy-Efficient Delay-Constrained Transmission and Sensing for Cognitive Radio SystemsMay 02 2012May 08 2012In this work we study energy-efficient transmission for Cognitive Radio (CR) which opportunistically operates on Primary User's (PU's) channel through spectrum sensing. Spectrum sensing and compulsory idling (for incumbent protection) introduce energy-overheads ... More
Temperature Effect and Fermi Surface Investigation in the Scanning Tunneling Microscopy of Bi$_2$Sr$_2$CaCu$_2$O$_8$Aug 07 2003Based on a Fermi liquid picture, the temperature effect on the impurity-induced spatial modulation of local density of states (LDOS) is investigated for the d-wave superconductor Bi$_2$Sr$_2$CaCu$_2$O$_8$, in the context of scanning tunneling microscopy ... More
Difference Discrete Variational Principle,EULER-Lagrange Cohomology and Symplectic, Multisymplectic StructuresJun 01 2001We study the difference discrete variational principle in the framework of multi-parameter differential approach by regarding the forward difference as an entire geometric object in view of noncomutative differential geometry. By virtue of this variational ... 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
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
First-principles investigation of half-metallic ferromagnetism of half-Heusler compounds XYZApr 01 2013Feb 18 2014We investigate the electronic structure and magnetism of half-Heusler compounds XYZ (X, Y=V, Cr, Mn, Fe, Co and Ni; Z=Al, Ga, In, Si, Ge, Sn, P, As, and Sb) using the ab initio density functional theory calculations. Nine half-metals with half-Heusler ... More
First-principle prediction of Martensitic transformation and magnetic properties of Heusler-type Pt2-xMn1+xGa alloysMar 28 2014Mar 02 2015The electronic structure, magnetism and phase stability of Pt2-xMn1+xGa(x=0, 0.25, 0.5, 0.75, 1) alloys are studied by first-principle calculations. The calculations reveal that a potential magnetic martensitic transformation can be expected in all the ... More
Super-Yangian Y(gl(1|1)) and Its Oscillator RealizationDec 02 1996On the basis of graded RTT formalism,the defining relation of the super-Yangian Y(gl(1|1)) is derived and its oscillator realization is constructed.
Pulsed γ-ray emission from magnetar 1E 2259+586Oct 19 2012Anomalous x-ray pulsars (AXPs) are thought to be magnetars which are young isolated neutron stars with extremely strong magnetic fields of > 10^14Gauss. Their tremendous magnetic fields inferred from the spin parameters provide a huge energy reservoir ... More
Separability and entanglement in 2x3xN composite quantum systemsAug 28 2003The separability and entanglement of quantum mixed states in $\Cb^2 \otimes \Cb^3 \otimes \Cb^N$ composite quantum systems are investigated. It is shown that all quantum states $\rho$ with positive partial transposes and rank $r(\rho)\leq N$ are separable. ... More
Bayesian binomial mixture models for estimating abundance in ecological monitoring studiesMay 11 2015Investigation of species abundance has become a vital component of many ecological monitoring studies. The primary objective of these studies is to understand how specific species are distributed across the study domain, as well as quantification of the ... More
3-dimensional arrays of BiSrCaCuO-2212 intrinsic Josephson junctions and the zero-crossing Shapiro steps at 760 GHzOct 11 2001On a slice of Bi_2Sr_2CaCu_2O_{8+x} 200~300 nm thick, stacks of intrinsic Josephson junctions are patterned, connected to each other, and integrated with a bow-tie antenna and some chokes. Over an area of 150 microns by 170 microns, so far we are able ... More
On the orbital properties of millisecond pulsar binariesJul 24 2018We report a detailed analysis of the orbital properties of binary millisecond pulsar (MSP) with a white dwarf (WD) companion. Positive correlations between the orbital period $P_{\rm b}$ and eccentricity $\epsilon$ are found in two classes of MSP binaries ... More
Conditioning of BPM pickup signals for operations of the Duke storage ring with a wide range of single-bunch currentNov 19 2013The Duke storage ring is a dedicated driver for the storage ring based oscillator free-electron lasers (FELs), and the High Intensity Gamma-ray Source (HIGS). It is operated with a beam current ranging from about 1 mA to 100 mA per bunch for various operations ... More
Superconducting energy gap and c-axis plasma frequency of (Nd,Sm)O0.82F0.18FeAs superconductors from infrared ellipsometryMay 15 2008We present ellipsometric measurements of the far-infrared dielectric response of polycrystalline samples of the new pnictide superconductor RO0.82F0.18FeAs (R=Nd and Sm). We find evidence that the electronic properties are strongly anisotropic such that ... More
Spin injection based on the spin gapless semiconductor(SGS)/semiconductor heterostructuresNov 21 2014Nov 28 2014Spin injection efficiency based on conventional ferromagnet (or half-metallic ferromagnet) /semiconductor is greatly limited by the Schmidt obstacle due to conductivity mismatch, here we proposed that by replacing the metallic injectors with spin gapless ... More
Magnetization flip in Fe-Cr-Ga systemDec 29 2018A systematic investigation about the structure and magnetism of Fe75-xCr25Gax (11<x<33) and Fe50Cr50-yGay (0<y<33) series has been carried out in this work. It shows that the parent Fe50Cr25Ga25 phase has higher tolerance for Ga replacing Cr than replacing ... More
Structure and magnetic properties of Heusler alloy Fe2NiZ (Z=Al, Ga, Si and Ge)Jan 31 2013The Heusler alloys Fe2NiZ (Z=Al, Ga, Si and Ge) have been synthesized and investigated focusing on the phase stability and the magnetic properties. The experimental and theoretical results reveal the covalent bonding originated from p-d hybridization ... More
Structure, magnetism and magnetic compensation behavior of Co50-xMn25Ga25+x and Co50-xMn25+xGa25 Heusler alloysOct 22 2012The structure, magnetism, magnetic compensation behavior, exchange interaction and electronic structures of Co50-xMn25Ga25+x and Co50-xMn25+xGa25 (x=0-25) alloys have been systematically investigated by both experiments and first-principles calculations. ... More
XMM-Newton observation of PSR B2224+65 and its jetDec 26 2011We have investigated the pulsar PSR B2224+65 and its X-ray jet with XMM-Newton. Apart from the long X-ray jet which is almost perpendicular to the direction of proper motion, a putative extended feature at the pulsar position, which oriented in the opposite ... More
Anti-sites disordering suppression of the possible phase transition in Mn2CrGaFeb 01 2016Theoretical and experimental characterizations of Mn2CrGa compound in regard to the possibility of phase transformation have been carried out in this work. Under a high ordering L21 structure, this compound has the potential to be a martensite phase transition ... More
Magneto-transport properties of oriented Mn2CoAl films sputtered on thermally oxidized Si substratesAug 07 2014Spin gapless semiconductors are interesting novel class of materials by embracing both magnetism and semiconducting. Its potential application in future spintronics requires realization in thin film form. In this letter, we report a successful growth ... 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
Structural and magnetic properties of MnCo1-xFexSi alloysMar 04 2015The crystal structures, martensitic structural transitions and magnetic properties of MnCo1-xFexSi (0 <= x <= 0.50) alloys were studied by differential scanning calorimetry (DSC), x-ray powder diffraction (XRD) and magnetic measurements. In high-temperature ... More
Gap opening and orbital modification of superconducting FeSe above the structural distortionFeb 03 2012We utilize steady-state and transient optical spectroscopies to examine the responses of nonthermal quasiparticles with respect to orbital modifications in normal-state iron-chalcogenide superconductors. The dynamics shows the emergence of gap-like quasiparticles ... More
Trapping of dark vector solitons in a fiber laserApr 17 2009May 07 2009We report on the experimental observation of incoherently coupled dark vector soliton trapping in a fiber laser. Dark vector solitons along the two orthogonal polarization directions though with large difference in central frequency, energy and darkness ... More
Model on pulsed GeV radiation from magnetarsFeb 27 2013We discuss a possible scenario for radiation mechanism of pulsed GeV gamma-rays from magnetars. The magnetars have shown frequent X-ray bursts, which would be triggered by crust fractures and could release the energy of order of ~10^{41-42}erg. If the ... More
A search for stellar X-ray sourcesin the Sagittarius and Carina dwarf galaxies - I: X-ray observationsSep 05 2006ROSAT observations found no convincing evidence for X-ray sources located in local dwarf spheroidal galaxies (dSph). Now with more sensitive instruments on board Chandra and XMM-Newton we can reach fainter luminosity levels. We report on an observation ... More
X-ray Beaming in the High Magnetic Field Pulsar GX 1+4Oct 29 1999Pulse profiles from X-ray pulsars often exhibit strong energy dependence and both periodic and aperiodic variations with time. The great variety of profiles observed in various sources, and even from individual sources, makes it difficult to separate ... More
Optimal state transfer of a single dissipative two-level systemApr 26 2016Optimal state transfer of a single two-level system (TLS) coupled to an Ohmic boson bath via off-diagonal TLS-bath coupling is studied by using optimal control theory. In the weak system-bath coupling regime where the time-dependent Bloch-Redfield formalism ... More
Theory of ball lightningNov 18 2014Dec 21 2015We present a comprehensive theory on the formation of ball lightning, a luminous sphere sometimes observed after normal lightning. In a ball lightning event, a relativistic electron bunch can be produced by the stepped leader of lightning and coherently ... More
The t system: a new system for estimating the total magnitudes of galaxiesDec 09 1997We present a new, but simple, procedure for estimating the total magnitudes of galaxies. This procedure involves the out-focusing of digital galaxy images numerically, the fitting of the resulting surface-brightness profiles with a single generalised ... More
Dark Soliton Fiber LaserMar 11 2009May 08 2009We report on the experimental observation of stable dark solitons in an all normal dispersion fiber laser. We found experimentally that dark soliton formation is a generic feature of the fiber laser under strong continuous wave (CW) emission. However, ... More
Canonical Form and Separability of PPT States in 2xMxN Composite Quantum SystemsDec 03 2003We investigate the canonical forms of positive partial transposition (PPT) density matrices in ${\cal C}^2 \otimes {\cal C}^M \otimes {\cal C}^N$ composite quantum systems with rank $N$. A general expression for these PPT states are explicitly obtained. ... More
Spin-Coupled Local Distortions in Multiferroic Hexagonal HoMnO3Oct 11 2009Local structural measurements have been performed on hexagonal HoMnO3 in order to ascertain the specific changes in bond distances which accompany magnetic ordering transitions. The transition from paramagnetic to the antiferromagetic (noncollinear) phase ... More
A computational approach to the twin paradox in curved spacetimeJun 07 2016Despite being a major component in the teaching of special relativity, the twin `paradox' is generally not examined in courses on general relativity. Due to the complexity of analytical solutions to the problem, the paradox is often neglected entirely, ... More
Unimpeded permeation of water through helium-leak-tight graphene-based membranesDec 15 2011Permeation through nanometer pores is important in the design of materials for filtration and separation techniques and because of unusual fundamental behavior arising at the molecular scale. We found that submicron-thick membranes made from graphene ... More
Crystal orientation and thickness dependence of superconductivity on tetragonal FeSe1-x thin filmsApr 12 2009Superconductivity was recently found in the simple tetragonal FeSe structure. Recent studies suggest that FeSe is unconventional, with the symmetry of the superconducting pairing state still under debate. To tackle these problems, clean single crystals ... More
Evidence for a quantum-spin-Hall phase in graphene decorated with Bi2Te3 nanoparticlesJun 19 2018Oct 16 2018Realization of the quantum-spin-Hall effect in graphene devices has remained an outstanding challenge dating back to the inception of the field of topological insulators. Graphene's exceptionally weak spin-orbit coupling -stemming from carbon's low mass- ... More
Granular front formation in free-surface flow of concentrated suspensionsFeb 19 2015Granular fronts are a common yet unexplained phenomenon emerging during the gravity driven free-surface flow of concentrated suspensions. They are usually believed to be the result of fluid convection in combination with particle size segregation. However, ... More
The fermion dynamical symmetry model for the even--even and even--odd nuclei in the Xe--Ba regionOct 08 1995The even--even and even--odd nuclei $^{126}$Xe-$^{132}$Xe and $^{131}$Ba-$^{137}$Ba are shown to have a well-realized $SO_8 \supset SO_6 \supset SO_3$ fermion dynamical symmetry. Their low-lying energy levels can be described by a unified analytical expression ... More
Local photocurrent generation in thin films of the topological insulator Bi2Se3Oct 17 2012We report on the optoelectronic properties of thin films of Bi2Se3 grown by molecular beam epitaxy. The films are patterned into circuits with typical extensions of tens of microns. In spatially resolved experiments, we observe submicron photocurrent ... More
The role of Cr substitution on the ferromagnetic properties of Ga1-xCrxNOct 26 2004Angular-dependent channeling Rutherford Backscattering Spectroscopy (c-RBS) has been used to quantify the fraction of Cr atoms on substitutional, interstitial, and random sites in epitaxial Ga1-xCrxN films grown by reactive molecular-beam epitaxy. The ... More
On the nature of the ultraluminous X-ray transient in Cen~A (NGC 5128)Sep 23 2005We combine 9 ROSAT, 9 Chandra, and 2 XMM-Newton observations of the Cen~A galaxy to obtain the X-ray light curve of 1RXH J132519.8-430312 (=CXOU J132519.9$-$430317) spanning 1990 to 2003. The source reached a peak 0.1-2.4 keV flux F_X>10^{-12} ergs cm^{-2} ... More
Statistics of random lasing modes and amplified spontaneous emission spikes in weakly scattering systemsMar 28 2007We have measured the spectral correlations and intensity statistics of random lasing modes in weakly scattering systems, and compared them to those of the amplified spontaneous emission spikes. Their dramatic differences revealed the distinct physical ... More
Role of covalent hybridization in martensitic structure and magnetic properties of shape memory alloys: the case of Ni50Mn5+xGa35-xCu10Dec 03 2012We have investigated the impact of covalent hybridization on martensitic structure and magnetic properties of Ni50Mn5+xGa35-xCu10 shape memory alloys. We found that the lattice distortion ((c-a)/a) of L10 martensite monotonously changes with the substitution ... More
Disorder-induced significant enhancement in magnetization of ball-milled Fe2CrGa alloyMar 20 2013A new disordered atom configuration in Fe2CrGa alloy has been created by ball-milling method. This leads to a significant enhancement of the magnetic moment up to 3.2~3.9 {\mu}B and an increase of Curie temperature by about 200 K, compared with the arc-melt ... More
Anomalous Hall effect and spin orbit torques in MnGa/IrMn films: Modification from strong spin Hall effect of antiferromagnetSep 27 2016We report systematic measurements of anomalous Hall effect(AHE) and spin orbit torques(SOT) in MnGa/IrMn films,, in which a single MnGa epitaxial layer reveals obvious orbital two-channel Kondo (2CK) effect. As increasing the thickness of the antiferromagnet ... More
Specific heat of the iron-based high-$T_c$ superconductor SmO$_{1-x}$F$_x$FeAsApr 23 2008May 23 2008The specific heat $C(T)$ of new iron-based high-$T_c$ superconductor SmO$_{1-x}$F$_x$FeAs ($0 \leq x \leq 0.2$) was systematically studied. For undoped $x$ = 0 sample, a specific heat jump was observed at 130 K. This is attributed to the structural or ... More
Prediction of topological insulating behavior in Hg2CuTi-type Heusler compounds from first principlesNov 01 2012The topological band structures of the X2YZ Heusler compounds with the Hg2CuTi structure are investigated by using first-principles calculations within density functional theory. Our results clearly show that a large number of the Hg2CuTi type Heusler ... More
Field-induced multiple metamagnetization in phase transition from paramagnetic austenite to ferromagnetic martensite in MnNi1-xFexGeJun 15 2010Tailoring the phase stability and magnetic structure by combining the antiferromagnetic MnNiGe martensite with ferromagnetic MnFeGe austenite, a magnetic-field-induced martensitic transformation has been achieved in MnNi1-xFexGe system. The doped Fe enables ... More
A new class of topological insulators from I-III-IV half-Heusler compounds with strong band inversion strengthOct 17 2013In this paper, by first principle calculations, we investigate systematically the band topology of a new half-Heusler family with composition of I(A)-III(A)-IV(A). The results clearly show that many of the I-III-IV half-Heusler compounds are in fact promising ... More
Nuclear symmetry energy and hadron-quark mixed phase in neutron starsNov 15 2018We study the hadron-quark mixed phase, which may occur in the interior of neutron stars. The relativistic mean-field model is employed to describe the hadronic phase, while the Nambu--Jona-Lasinio model is used for the quark phase. We examine the effects ... More
Fieldbus Device Drivers for Accelerator Control at DESYNov 21 2001In order to interface the DESY fieldbus adapter, SEDAC (SErial Data Acquisition and Control system), a full duplex device driver was developed for the Windows NT, Linux, VxWorks, and Solaris operating systems. Detailed driver development issues as well ... More
An explanation of trans-ionospheric pulse pairsAug 23 2016Trans-ionospheric pulse pairs are the most powerful natural radio signals on the Earth and associated with lightning. They have been discovered for two decades by satellites, but their origin still remains elusive. Here we attribute these radio signals ... More
Nonstoichiometric doping and Bi antisite defect in single crystal Bi2Se3Aug 08 2012We studied the defects of Bi2Se3 generated from Bridgman growth of stoichiometric and nonstoichiometric self-fluxes. Growth habit, lattice size, and transport properties are strongly affected by the types of defect generated. Major defect types of Bi_Se ... More
Chandra detection of a new diffuse X-ray component from the globular cluster 47 TucanaeMay 21 2014May 22 2014In re-analyzing the archival Chandra data of the globular cluster 47 Tucanae, we have detected a new diffuse X-ray emission feature within the half-mass radius of the cluster. The spectrum of the diffuse emission can be described by a power-law model ... More
Microwave imaging of a hot flux rope structure during the pre-impulsive stage of an eruptive M7.7 solar flareMar 09 2016Corona structures and processes during the pre-impulsive stage of solar eruption are crucial to understanding the physics leading to the subsequent explosive energy release. Here we present the first microwave imaging study of a hot flux rope structure ... More
Antisite disorder driven spontaneous exchange bias effect in La2-xSrxCoMnO6 (0<x<1)Aug 01 2015Doping at the rare-earth site by divalent alkaline-earth ions in perovskite lattice has witnessed a variety of magnetic and electronic orders with spatially correlated charge, spin and orbital degrees of freedom. Here, we report an antisite disorder driven ... More
A New Spin Gapless Semiconductors Family: Quaternary Heusler CompoundsJan 31 2013Using first-principles calculations, we investigate the band structures of a series of quaternary LiMgPdSn-type Heusler compounds. Our calculation results show that five compounds CoFeMnSi, CoFeCrAl, CoMnCrSi, CoFeVSi and FeMnCrSb possess unique electronic ... More
Thermodynamic properties of Ba1-xMxFe2As2 (M = La and K)Jun 22 2008Jun 30 2008The specific heat $C(T)$ of BaFe$_2$As$_2$ single crystal, electron-doped Ba$_{0.7}$La$_{0.3}$Fe$_2$As$_2$ and hole-doped Ba$_{0.5}$K$_{0.5}$Fe$_2$As$_2$ polycrystals were measured. For undoped BaFe$_2$As$_2$ single crystal, a very sharp specific heat ... More
Enhanced spin-orbit torques in MnAl/Ta films with improving chemical orderingFeb 26 2017We report the enhancement of spin-orbit torques in MnAl/Ta films with improving chemical ordering through annealing. The switching current density is increased due to enhanced saturation magnetization MS and effective anisotropy field HK after annealing. ... More
The complex superstructure in Mg1-xAlxB2 at x~0.5Sep 17 2001Electron diffraction and high resolution microscopy have been performed on Mg1-xAlxB2 with x~0.5. This composition displays a superstructure with a repeat period of exactly 2c along the c axis and about 10 nm in the a-b plane. The superstructure results ... More
Development and Application of a Diaphragm Micro-Pump with Piezoelectric DeviceFeb 21 2008In this study, a new type of thin, compact, and light weighed diaphragm micro-pump has been successfully developed to actuate the liquid by the vibration of a diaphragm. The micro-diaphragm pump with two valves is fabricated in an aluminum case by using ... More
Ferromagnetic structures in Mn2CoGa and Mn2CoAl doped by Co, Cu, V, and TiOct 19 2012The structure and magnetic properties in doped Heusler alloys of Mn2CoGa and Mn2CoAl have been investigated by experiments and calculations. The main group elements of Ga and Al are substituted by the magnetic or non-magnetic transition metals, Co, Cu, ... More
Structural transitions, magnetic properties, and electronic structures of Co(Fe)-doped MnNiSi compoundsNov 21 2014The structural transitions, magnetic properties, and electronic structures of Co(Fe)-doped MnNiSi compounds are investigated by x-ray powder diffraction (XRD), differential scanning calorimetry (DSC), magnetic measurements, and first-principles calculations. ... More
Pressure Effects on the Superconducting and Spin-Density-Wave States of the Newly Discovered Sm(O1-xFx)FeAsApr 10 2008Aug 04 2008High temperature superconductors with a Tc above 40 K have been found to be strongly correlated electron systems and to have a layered structure. Guided by these rules, Kamihara et al. discovered a Tc up to 26 K in the layered La(O1-xFx)FeAs. By replacing ... More
Metamagnetic behavior and effect of field cooling on sharp magnetization jumps in multiferroic Y2CoMnO6Jul 31 2014Oct 13 2014We present sharp magnetization jumps and field induced irreversibility in magnetization in multiferroic Y2CoMnO6. Appearance of magnetic relaxation and field sweep rate dependence of magnetization jumps resemble the martensite like scenario and suggests ... More
A detailed X-ray investigation of PSR J2021+4026 and $γ$-Cygni supernova remnantNov 09 2014We have investigated the field around the radio-quiet $\gamma$-ray pulsar, PSR J2021+4026, with a ~140 ks XMM-Newton observation and a ~56 ks archival Chandra data. Through analyzing the pulsed spectrum, we show that the X-ray pulsation is purely thermal ... More