Results for "Y. R. Niu"

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Possible discovery of the r-process characteristics in the abundances of metal-rich barium starsMay 16 2014We study the abundance distributions of a sample of metal-rich barium stars provided by Pereira et al. (2011) to investigate the s- and r-process nucleosynthesis in the metal-rich environment. We compared the theoretical results predicted by a parametric ... More
Ultrabroadband photosensitivity from visible to terahertz at room temperatureJun 23 2018Charge-density wave (CDW) is one of the most fundamental quantum phenomena in solids. Different from ordinary metals in which only single particle excitations exist, CDW also has collective excitations and can carry electric current in a collective fashion. ... More
Suppressed carrier density for the patterned high mobility two-dimensional electron gas at gamma-Al2O3/SrTiO3 heterointerfacesJun 28 2017The two-dimensional electron gas (2DEG) at the non-isostructural interface between spinel gamma-Al2O3 and perovskite SrTiO3 is featured by a record electron mobility among complex oxide interfaces in addition to a high carrier density up to the order ... More
Nuclear $β$-decay half-lives in the relativistic point-coupling modelMar 04 2015Oct 28 2015The self-consistent proton-neutron quasiparticle random phase approximation approach is employed to calculate $\beta$-decay half-lives of neutron-rich even-even nuclei with $8\leqslant Z \leqslant 30$. A newly proposed nonlinear point-coupling effective ... More
Anomalous Nernst and Hall effects in magnetized platinum and palladiumJun 04 2014We study the anomalous Nernst effect (ANE) and anomalous Hall effect (AHE) in proximity-induced ferromagnetic palladium and platinum which is widely used in spintronics, within the Berry phase formalism based on the relativistic band structure calculations. ... More
Ab initio calculation of intrinsic spin Hall effect in semiconductorsMay 06 2005Relativistic band theoretical calculations reveal that intrinsic spin Hall conductivity in hole-doped archetypical semiconductors Ge, GaAs and AlAs is large $[\sim 100 (\hbar/e)(\Omega cm)^{-1}]$, showing the possibility of spin Hall effect beyond the ... More
Nuclear effective charge factor originating from covariant density functional theoryMay 24 2013Guiding by the relativistic local density approximation, we explore a phenomenological formula for the coupling strength of Coulomb field to take into account the Coulomb exchange term effectively in the relativistic Hartree approximation. Its validity ... More
Nuclear $β^+$/EC decays in covariant density functional theory and the impact of isoscalar proton-neutron pairingMay 23 2013Self-consistent proton-neutron quasiparticle random phase approximation based on the spherical nonlinear point-coupling relativistic Hartree-Bogoliubov theory is established and used to investigate the $\beta^+$/EC-decay half-lives of neutron-deficient ... More
Anisotropic two-gap superconductivity and the absence of a Pauli paramagnetic limit in single-crystalline LaO$_{0.5}$F$_{0.5}$BiS$_2$Oct 30 2017Mar 20 2018Ambient-pressure-grown LaO$_{0.5}$F$_{0.5}$BiS$_2$ with a superconducting transition temperature $T_{c}\sim$3K possesses a highly anisotropic normal state. By a series of electrical resistivity measurements with a magnetic field direction varying between ... More
Improved radial basis function approach with the odd-even correctionsJul 07 2016The radial basis function (RBF) approach has been used to improve the mass predictions of nuclear models. However, systematic deviations exist between the improved masses and the experimental data for nuclei with different odd-even parities of ($Z$, $N$), ... More
Photoemission study of the electronic structure and charge density waves of Na2Ti2Sb2OMay 08 2015The electronic structure of Na2Ti2Sb2O, a parent compound of the newly discovered titanium-based oxypnictide superconductors, is studied by photon energy and polarization dependent angle-resolved photoemission spectroscopy (ARPES). The obtained band structure ... More
Controllable spin-orbit coupling and its influence on the upper critical field in the chemically doped quasi-one-dimensional Nb$_2$PdS$_5$ superconductorSep 30 2014By systematic chemical substitution of Pt and Ni in the newly-discovered superconductor Nb$_2$PdS$_5$ ($T_c\sim$6 K), we study the evolution of its superconducting properties with doping, focussing on the behavior of the upper critical field $H_{c2}$. ... More
Superconductivity across Lifshitz transition and anomalous insulating state in surface K-dosed (Li0.8Fe0.2OH)FeSeAug 18 2017In the iron-based superconductors, understanding the relation between superconductivity and electronic structure upon doping is crucial for exploring the pairing mechanism. Recently it was found that in iron selenide (FeSe), enhanced superconductivity ... More
Dynamic Fractional Stark Ladders in DC--AC FieldsDec 09 1993Dec 09 1994A single band in a spatially periodic system splits into a series of quasienergy subbands under the action of DC--AC electric fields. These dynamic fractional Stark ladders should be observable in an investigation of optical absorption.
Giant tunability of the two-dimensional electron gas at the interface of gamma-Al2O3/SrTiO3Oct 23 2017Herein, we reported giant tunability of the physical properties of 2DEGs at the spinel/perovskite interface of {\gamma}-Al2O3/SrTiO3 (GAO/STO). By modulating the carrier density thus the band filling with ionic-liquid gating, the system experiences a ... More
Pumping in an interacting quantum wireJun 06 2003We study charge and spin pumping in an interacting one-dimensional wire. We show that a spatially periodic potential modulated in space and time acts as a quantum pump inducing a dc-current component at zero bias. The current generated by the pump is ... More
Predictions of nuclear $β$-decay half-lives with machine learning and their impacts on $r$ processOct 07 2018Nuclear $\beta$ decay is a key process to understand the origin of heavy elements in the universe, while the accuracy is far from satisfactory for the predictions of $\beta$-decay half-lives by nuclear models up to date. In this letter, we pave a novel ... More
Self-consistent relativistic quasiparticle random-phase approximation and its applications to charge-exchange excitations and $β$-decay half-livesApr 24 2016The self-consistent quasiparticle random-phase approximation (QRPA) approach is formulated in the canonical single-nucleon basis of the relativistic Hatree-Fock-Bogoliubov (RHFB) theory. This approach is applied to study the isobaric analog states (IAS) ... More
DC-transport properties of ferromagnetic (Ga,Mn)As semiconductorsFeb 03 2003We study the dc transport properties of (Ga,Mn)As diluted magnetic semiconductors with Mn concentration varying from 1.5% to 8%. Both diagonal and Hall components of the conductivity tensor are strongly sensitive to the magnetic state of these semiconductors. ... More
Observation of weakened V-V dimers in the monoclinic metallic phase of strained VO2Mar 13 2019Emergent order at mesoscopic length scales in condensed matter can provide fundamental insight into the underlying competing interactions and their relationship with the order parameter. Using spectromicroscopy, we show that mesoscopic stripe order near ... More
Direct Observation of Decoupled Structural and Electronic Transitions and an Ambient Pressure Monoclinic-Like Metallic Phase of VO$_2$Nov 17 2014We report the simultaneous measurement of the structural and electronic components of the metal-insulator transition of VO$_2$ using electron and photoelectron spectroscopies and microscopies. We show that these evolve over different temperature scales, ... More
Low-energy isovector and isoscalar dipole response in neutron-rich nucleiFeb 25 2012The self-consistent random phase approximation (RPA), based on the framework of relativistic energy density functionals, is employed in the study of isovector and isoscalar dipole response in $^{68}$Ni, $^{132}$Sn, and $^{208}$Pb. The evolution of pygmy ... More
On the isoscalar-isovector splitting of pygmy dipole structuresMay 29 2009The electric dipole response of $^{140}$Ce is investigated using the fully consistent relativistic quasiparticle random phase approximation. By analyzing the isospin structure of the E1 response, it is shown that the low-energy (pygmy) strength separates ... More
Nuclear excitations within microscopic EDF approaches : pairing and temperature effects on the dipole responseApr 25 2019In the present work, the isovector dipole responses, both in the resonance region and in the low-energy sector, are investigated using the microscopic nuclear Energy Density Functionals (EDFs). The self-consistent QRPA model based on Skyrme Hartree Fock ... More
Low-energy quadrupole states in neutron-rich tin nucleiJun 14 2018We present a study on the isoscalar quadrupole strength in tin nuclei, focusing mainly on the low-energy region. The calculations are performed using the Skyrme type energy density functionals within the fully self-consistent quasiparticle random phase ... More
Low-energy multipole response in nuclei at finite temperatureJun 16 2009The multipole response of nuclei at temperatures T=0-2 MeV is studied using a self-consistent finite-temperature RPA (random phase approximation) based on relativistic energy density functionals. Illustrative calculations are performed for the isoscalar ... More
Stability of Strutinsky Shell Correction Energy in Relativistic Mean Field TheoryOct 23 2009The single-particle spectrum obtained from the relativistic mean field (RMF) theory is used to extract the shell correction energy with the Strutinsky method. Considering the delicate balance between the plateau condition in the Strutinsky smoothing procedure ... More
Radial basis function approach in nuclear mass predictionsSep 02 2013The radial basis function (RBF) approach is applied in predicting nuclear masses for 8 widely used nuclear mass models, ranging from macroscopic-microscopic to microscopic types. A significantly improved accuracy in computing nuclear masses is obtained, ... More
The weak electronic correlations and absence of heavy Fermion state in KNi$_2$Se$_2$Nov 24 2014We have studied the low-lying electronic structure of a new ThCr$_2$Si$_2$-type superconductor KNi$_2$Se$_2$ with angle-resolved photoemission spectroscopy. Three bands intersect the Fermi level, forming complicated Fermi surface topology, which is sharply ... More
Extraordinary quasiparticle scattering and bandwidth-control by dopants in iron-based superconductorsApr 27 2014The diversities in crystal structures and ways of doping result in extremely diversified phase diagrams for iron-based superconductors. With angle-resolved photoemission spectroscopy (ARPES), we have systematically studied the effects of chemical substitution ... More
Angle-resolved Photoemission Spectroscopy Study on the Surface States of the Correlated Topological Insulator YbB6Apr 24 2014We report the electronic structure of YbB6, a recently predicted moderately correlated topological insulator, measured by angle-resolved photoemission spectroscopy. We directly observed linearly dispersive bands around the time-reversal invariant momenta ... More
Electronic Structure of Single Crystalline NdO$_{0.5}$F$_{0.5}$BiS$_{2}$ Studied by Angle-resolved Photoemission SpectroscopyFeb 12 2014NdO$_{0.5}$F$_{0.5}$BiS$_{2}$ is a new layered superconductor. We have studied the low-lying electronic structure of a single crystalline NdO$_{0.5}$F$_{0.5}$BiS$_{2}$ superconductor, whose superconducting transition temperature is 4.87K, with angle-resolved ... More
$β$-decay half-lives of neutron-rich nuclei and matter flow in the $r$-processOct 02 2012May 24 2013The $\beta$-decay half-lives of neutron-rich nuclei with $20 \leqslant Z \leqslant 50$ are systematically investigated using the newly developed fully self-consistent proton-neutron quasiparticle random phase approximation (QRPA), based on the spherical ... More
Pairing transitions in the finite-temperature relativistic Hartree-Bogoliubov theoryJun 20 2013Jan 20 2014We formulate the finite-temperature relativistic Hartree-Bogoliubov theory for spherical nuclei based on a point-coupling functional, with the Gogny or separable pairing force. Using the functional PC-PK1, the framework is applied to the study of pairing ... More
Systematic calculations of $α$-decay half-lives with an improved empirical formulaMar 05 2015Based on the recent data in NUBASE2012, an improved empirical formula for evaluating the $\alpha$-decay half-lives is presented, in which the hindrance effect resulted from the change of the ground state spins and parities of parent and daughter nuclei ... More
PSR B0826-34: Sometimes a rotating radio transientSep 26 2012Oct 18 2012We report on the detection of sporadic, strong single pulses co-existing with a periodic weak emission in the duration of weak mode of PSR B0826-34. The intensities and durations of these pulses are comparable with that of the sub-pulses in the strong ... More
A Dynamic Additive and Multiplicative Effects Model with Application to the United Nations Voting BehaviorsMar 18 2018Mar 22 2018In this paper, we introduce a statistical regression model for discrete-time networks that are correlated over time. Our model is a dynamic version of a Gaussian additive and multiplicative effects (DAME) model which extends the latent factor network ... More
A High Reliability Asymptotic Approach for Packet Inter-Delivery Time Optimization in Cyber-Physical SystemsApr 13 2015In cyber-physical systems such as automobiles, measurement data from sensor nodes should be delivered to other consumer nodes such as actuators in a regular fashion. But, in practical systems over unreliable media such as wireless, it is a significant ... More
Strong photon blockade with intracavity electromagnetically induced transparency in blockaded Rydberg ensembleAug 13 2013Dec 14 2015We consider the dynamics of intracavity electromagnetically induced transparency (EIT) in an ensemble of strongly interacting Rydberg atoms. By combining the advantage of variable cavity lifetimes with intracavity EIT and strongly interacting Rydberg ... More
Prediction of novel stable compounds in the Mg-Si-O system under exoplanet pressuresOct 11 2015The Mg-Si-O system is the major Earth and rocky planet-forming system. Here, through quantum variable-composition evolutionary structure explorations, we have discovered several unexpected stable binary and ternary compounds in the Mg-Si-O system. Besides ... More
Optimal Energy-Efficient Regular Delivery of Packets in Cyber-Physical SystemsFeb 27 2015In cyber-physical systems such as in-vehicle wireless sensor networks, a large number of sensor nodes continually generate measurements that should be received by other nodes such as actuators in a regular fashion. Meanwhile, energy-efficiency is also ... More
Tunable ultranarrow linewidth of cavity induced by interacting dark resonancesJun 17 2009A scheme for getting a tunable ultranarrow linewidth of a cavity due to an embedded four-level atomic medium with double-dark resonances is proposed. It is shown that the steep dispersion induced by double-dark resonances in the transparency window leads ... More
Electronic structure and 4f-electron character in Ce2PdIn8 studied by angle-resolved photoemission spectroscopyFeb 15 2019The localized-to-itinerant transition of f electrons lies at the heart of heavy-fermion physics, but has only been directly observed in single-layer Ce-based materials. Here, we report a comprehensive study on the electronic structure and nature of the ... More
Drastic electronic structure reconstruction of Ca$_{1-x}$Pr$_x$Fe$_2$As$_2$ in the collapsed tetragonal phaseOct 22 2014Oct 24 2014We report the electronic structure reconstruction of Ca$_{1-x}$Pr$_x$Fe$_2$As$_2$ ($x$ = 0.1 and 0.15) in the low temperature collapsed tetragonal (CT) phase observed by angle-resolved photoemission spectroscopy. Different from Ca(Fe$_{1-x}$Rh$_x$)$_2$As$_2$ ... More
The unique electronic structure of Ca10(Pt4As8)(Fe2-xPtxAs2)5 with metallic Pt4As8 layersAug 13 2013We studied the low-lying electronic structure of the newly discovered iron-platinum-arsenide superconductor, Ca10(Pt4As8)(Fe2-xPtxAs2)5 (Tc=22 K) with angle-resolved photoemission spectroscopy. We found that the Pt4As8 layer contributes to a small electron-like ... More
Surface electronic structure and evidence of plain s-wave superconductivity in (Li0.8Fe0.2)OHFeSeJul 09 2015Oct 04 2016(Li0.8Fe0.2)OHFeSe is a newly-discovered intercalated iron-selenide superconductor with a Tc above 40 K, which is much higher than the Tc of bulk FeSe (8 K). Here we report a systematic study of (Li0.8Fe0.2)OHFeSe by low temperature scanning tunneling ... More
Unveiling the superconducting mechanism of Ba$_{0.51}$K$_{0.49}$BiO$_3$Feb 28 2018Bismuthates were the first family of oxide high-temperature superconductors, exhibiting superconducting transition temperatures (Tc) up to 32K, but the superconducting mechanism remains under debate despite more than 30 years of extensive research. Our ... More
Quantum spin Hall effect and topological phase transitions in honeycomb antiferromagnetsMay 19 2017While the quantum spin Hall (QSH) effect and antiferromagnetic order constitute two of the most promising phenomena for embedding basic spintronic concepts into future technologies, almost all of the QSH insulators known to date are non-magnetic. Here, ... More
Two-Color Photon Correlations of the Light Scattered by a Quantum DotJan 05 2015Two-color second-order correlations of the light scattered near-resonantly by a quantum dot were measured by means of spectrally-filtered coincidence detection. The effects of filter frequency and bandwidth were studied under monochromatic laser excitation, ... More
Multipole excitations in hot nuclei within the finite temperature quasiparticle random phase approximation frameworkAug 08 2017The effect of temperature on the evolution of the isovector dipole and isoscalar quadrupole excitations in $^{68}$Ni and $^{120}$Sn nuclei is studied within the fully self-consistent finite temperature quasiparticle random phase approximation framework, ... More
Controlled Creation of Spatial Superposition States for Single AtomsNov 16 2006We present a method for the controlled and robust generation of spatial superposition states of single atoms in micro-traps. Using a counter-intuitive positioning sequence for the individual potentials and appropriately chosen trapping frequencies, we ... More
Band dependent inter-layer $f$-electron hybridization in CeRhIn$_5$Jan 23 2018A key issue in heavy fermion research is how subtle changes in the hybridization between the 4$f$ (5$f$) and conduction electrons can result in fundamentally different ground states. CeRhIn$_5$ stands out as a particularly notable example: replacing Rh ... More
Topological Crystalline Insulator and Quantum Anomalous Hall States in IV-VI based Monolayers and their Quantum WellsMar 06 2015Different from the two-dimensional (2D) topological insulator, the 2D topological crystalline insulator (TCI) phase disappears when the mirror symmetry is broken, e.g., upon placing on a substrate. Here, based on a new family of 2D TCIs - SnTe and PbTe ... More
Quasi-particle random phase approximation with quasi-particle-vibration coupling: application to the Gamow-Teller response of the superfluid nucleus $^{120}$SnSep 08 2016We propose a self-consistent quasi-particle random phase approximation (QRPA) plus quasi-particle-vibration coupling (QPVC) model with Skyrme interactions to describe the width and the line shape of giant resonances in open-shell nuclei, in which the ... More
Direct observation of how the heavy fermion state develops in CeCoIn5Oct 21 2016Heavy fermion materials gain high electronic masses and expand Fermi surfaces when the high-temperature localized f electrons become itinerant and hybridize with the conduction band at low temperatures. However, despite the common application of this ... More
Reexamining the temperature and neutron density conditions for r-process nucleosynthesis with augmented nuclear mass modelsAug 11 2012Jan 30 2013We explore the effects of nuclear masses on the temperature and neutron density conditions required for r-process nucleosynthesis using four nuclear mass models augmented by the latest atomic mass evaluation. For each model we derive the conditions for ... More
Constraint on the cosmic age from the solar $r$-process abundancesMar 07 2014The cosmic age is an important physical quantity in cosmology. Based on the radiometric method, a reliable lower limit of the cosmic age is derived to be $15.68\pm 1.95$ Gyr by using the $r$-process abundances inferred for the solar system and observations ... More
Cavity linewidth narrowing with dark-state polaritonsAug 14 2013Apr 09 2015We perform a quantum-theoretical treatment of cavity linewidth narrowing with intracavity electromagnetically induced transparency (EIT). By means of intracavity EIT, the photons in the cavity are in the form of cavity polaritons: bright-state polariton ... More
Towards a self-consistent dynamical nuclear modelJan 04 2017Density Functional Theory (DFT) is a powerful and accurate tool exploited in Nuclear Physics to investigate the ground-state and some collective properties of nuclei along the whole nuclear chart. Models based on DFT are, however, not suitable for the ... More
Reflectarray antennas for terahertz communicationsOct 02 2012Reflectarrays composed of resonant microstrip gold patches on a dielectric substrate are demonstrated for operation at terahertz frequencies. Based on the relation between the patch size and the reflection phase, a progressive phase distribution is implemented ... More
Emergence and stability of spontaneous vortex lattices in exciton-polariton condensatesJan 10 2019Jan 11 2019The spontaneous formation of lattice structure of quantized vortices is a characteristic feature of superfluidity in closed systems under thermal equilibrium. In exciton-polariton Bose-Einstein condensate, which is a typical example of macroscopic quantum ... More
Tellurene-a monolayer of tellurium from first-principles predictionMay 11 2016A two dimensional (2D) Group-VI Te monolayer, tellurene, is predicted by using the first-principles calculations, which consists of planner four-membered and chair-like six-membered rings arranged alternately in a 2D lattice. The phonon spectra calculations, ... More
On Determining Dead Layer and Detector Thicknesses for a Position-Sensitive Silicon DetectorJan 18 2018In this work, two particular properties of the position-sensitive, thick silicon detectors (known as the "E" detectors) in the High Resolution Array (HiRA) are investigated: the thickness of the dead layer on the front of the detector, and the overall ... More
Tunable narrow band source via the strong coupling between optical emitter and nanowire surface plasmonsDec 30 2014The spectrum width can be narrowed to a certain degree by decreasing the coupling strength for the two-level emitter coupled to the propagating surface plasmon. But the width can not be narrowed any further because of the loss of the photon out of system ... More
Quantum Nondemolition Measurement and Heralded Preparation of Fock States with Electromagnetically Induced Transparency in an Optical CavityMar 01 2012Mar 29 2012We propose a technique for quantum nondemolition (QND) measurement and heralded preparation of Fock states by dynamics of electromagnetically induced transparency (EIT). An atomic ensemble trapped in an optical cavity is driven by two external continuous-wave ... More
Influence of heat treatment excursion on critical current and residual resistivity ratio of ITER Nb3Sn strandsJan 30 2017Heat treatment is critically important to the performance of Nb3Sn superconducting strands. For very large Nb3Sn magnet coils, such as the International Thermonuclear Experimental Reactor (ITER) Central Solenoid (CS) coils, heat treatment carries risk ... More
Observation of in-gap surface states in the Kondo insulator SmB6 by photoemissionJun 24 2013Kondo insulators (KIs) are strongly correlated materials in which the interactions between 4f and conduction electrons lead to a hybridization gap opening at low temperature 1-2. SmB6 is a typical KI, but its resistivity does not diverge at low temperatures, ... More
Surface electronic structure and isotropic superconducting gap in (Li$_{0.8}$Fe$_{0.2}$)OHFeSeJun 09 2015Using angle-resolved photoemission spectroscopy (ARPES), we revealed the surface electronic structure and superconducting gap of (Li$_{0.8}$Fe$_{0.2}$)OHFeSe, an intercalated FeSe-derived superconductor without antiferromagnetic phase or Fe-vacancy order ... More
Identification of prototypical Brinkman-Rice Mott physics in a class of iron chalcogenides superconductorsJun 12 2015Feb 23 2016The 122$^{*}$ series of iron-chalcogenide superconductors, for example K$_x$Fe$_{2-y}$Se$_{2}$, only possesses electron Fermi pockets. Their distinctive electronic structure challenges the picture built upon iron pnictide superconductors, where both electron ... More
Weakening of the diamagnetic shielding in FeSe$_{1-x}$S$_x$ at high pressuresMay 22 2017Jul 10 2017The superconducting transition of FeSe$_{1-x}$S$_x$ with three distinct sulphur concentrations $x$ was studied under hydrostatic pressure up to $\sim$70 kbar via bulk AC susceptibility. The pressure dependence of the superconducting transition temperature ... More
On Behaviors of Maximal DimensionJan 25 2018Jan 26 2018In this paper, we investigate behaviors of Maximal Dimension, a group invariant involving certain configuration of maximal subgroups, which we denote by MaxDim. We prove that in some special cases, MaxDim(G\times H) = MaxDim(G) + MaxDim(H). We also prove ... More
Castelnuovo-Mumford regularity bounds for singular surfacesJun 27 2013Aug 10 2015We prove the regularity conjecture, namely Eisenbud-Goto conjecture, for a normal surface with rational, Gorenstein elliptic and log canonical singularities. Along the way, we bound the regularity for a dimension zero scheme by its Loewy length and for ... More
Vanishing theorems for Mather-Jacobian multiplier ideals on a Gorenstein projective varietyAug 10 2015In this paper, we establish several results related to vanishing theorems for Mather-Jacobian multiplier ideals on a Gorenstein projective variety, including an injectivity theorem, a Nadel-type vanishing theorem, a Griffith-type vanishing theorem for ... More
On a Conjecture of Cai-Zhang-Shen for Figurate PrimesJan 19 2019A conjecture of Cai-Zhang-Shen for figurate primes says that every integer n > 1 is the sum of two figurate primes. In this paper we give a proposition which is equivalent to the conjecture, and then confirm the conjecture under suitable conditions by ... More
On Nontrivial Zeros of Riemann Zeta FunctionApr 17 2017Jul 17 2018Let {\Xi} be a function relating to the Riemann zeta function with . In this paper, we construct a function containing and {\Xi} , and prove that satisfies a nonadjoint boundary value problem to a nonsingular differential equation if is any nontrivial ... More
On a Conjecture of Cai-Zhang-Shen for Figurate PrimesJan 19 2019Apr 27 2019A conjecture of Cai-Zhang-Shen for figurate primes says that every integer n > 1 is the sum of two figurate primes. In this paper we give respectively equivalent propositions to the conjecture in the cases of even and odd integers and then confirm the ... More
Some Results on Asymptotic Regularity of Ideal SheavesJun 14 2011Let $\mathscr{I}$ be an ideal sheaf on $P^n$ defining a subscheme $X$. Associated to $\mathscr{I}$ there are two elementary invariants: the invariant $s$ which measures the positivity of $\mathscr{I}$, and the minimal number $d$ such that $\mathscr{I}(d)$ ... More
Mean dimension and AH-algebras with diagonal mapsOct 04 2010Feb 01 2014Mean dimension for AH-algebras is introduced. It is shown that if a simple unital AH-algebra with diagonal maps has mean dimension zero, then it has strict comparison on positive elements. In particular, the strict order on projections is determined by ... More
Singularities of generic linkage of algebraic varietiesJul 04 2012Jun 18 2013Let $Y$ be a generic link of a subvariety $X$ of a nonsingular variety $A$. We give a description of the Grauert-Riemenschneider canonical sheaf of $Y$ in terms of the multiplier ideal sheaves associated to $X$ and use it to study the singularities of ... More
Codimension-two Bifurcations Induce Hysteresis Behavior and Multistabilities in Delay-coupled Kuramoto OscillatorsAug 11 2016Hysteresis phenomena and multistability play crucial roles in the dynamics of coupled oscillators, which are now interpreted from the point of view of codimension-two bifurcations. On the Ott-Antonsen's manifold, complete bifurcation sets of delay-coupled ... More
A Vanishing Theorem and Asymptotic Regularity of Powers of Ideal SheavesSep 02 2010Jun 14 2011Let $\mathscr{I}$ be an ideal sheaf on $P^n$. In the first part of this paper, we bound the asymptotic regularity of powers of $\mathscr{I}$ as $ps-3\leq \reg \mathscr{I}^p\leq ps+e$, where $e$ is a constant and $s$ is the $s$-invariant of $\mathscr{I}$. ... More
Mather-Jacobian singularities under generic linkageOct 26 2015Sep 26 2016In this paper, we prove that Mather-Jacobian (MJ) singularities are preserved under the process of generic linkage. More precisely, let $X$ be a variety with MJ-canonical (resp. MJ-log canonical) singularities. Then a generic link of $X$ is also MJ-canonical ... More
Geometric nullstellensatz and symbolic powers on arbitrary varietiesJan 18 2013Jan 22 2014In recent years, a multiplier ideal defined on arbitrary varieties, so called Mather multiplier ideal, has been developed independently by Ein-Ishii-Mustata, and de Fernex-Docampo. With this new tool, we have a chance of extending some classical results ... More
Quantized Density Response in InsulatorsMar 18 1994The response of particle density to a dilation of a periodic potential in an insulator, with or without a fixed background potential or a magnetic field, is shown to be quantized. A similar phenomenon occurs in a quantum Hall system, where the derivative ... More
A Bound for the Castelnuovo-Mumford Regularity of Log Canonical VarietiesDec 17 2009Feb 01 2011In this note, we give a bound for the Castelnuovo-Mumford regularity of a homogeneous ideal $I$ in terms of the degrees of its generators. We assume that $I$ defines a local complete intersection with log canonical singularities.
Radiation properties of extreme nulling pulsar J1502-5653Jun 27 2012We report on radiation properties of extreme nulling pulsar J1502-5653, by analyzing the data acquired from the Parkes 64-m telescope at 1374 MHz. The radio emission from this pulsar exhibits sequences of several tens to several hundreds consecutive burst ... More
Quantized Vortices in Superfluids and SuperconductorsSep 10 1997We give a general review of recent developments in the theory of vortices in superfluids and superconductors, discussing why the dynamics of vortices is important, and why some key results are still controversial. We discuss work that we have done on ... More
A metallic phase in quantum Hall systemsOct 06 2001The electronic eigenstates of a quantum Hall (QH) system are chiral states. Strong inter-Landau-band mixings among these states can occur when the bandwidth is comparable to the spacing of two adjacent Landau bands. We show that mixing of localized states ... More
The Edge-State Theory of Integer-Quantum-Hall-Effect to Insulator TransitionAug 28 2000Direct transitions, driven by disorder, from several integral quantum Hall states to an insulator have been observed in experiment. This finding is enigmatic in light of a theoretical phase diagram, based on rather general considerations, that predicts ... More
Diverse Chemistry of Stable Hydronitrogens, and Implications for Planetary and Materials SciencesNov 17 2014Apr 25 2016Nitrogen hydrides, including ammonia (NH3), hydrazine (N2H4), hydrazoic acid (HN3) and etc, are compounds of great fundamental and applied importance. Their high-pressure behavior is important because of their abundance in giant planets and because of ... More
Temperature and Electron Density Dependence of Spin Relaxation in GaAs/AlGaAs Quantum WellOct 29 2010Temperature and carrier density dependent spin dynamics for GaAs/AlGaAs quantum wells (QWs) with different structural symmetry has been studied by using time-resolved Kerr rotation technique. The spin relaxation time is measured to be much longer for ... More
Nearly isotropic superconductivity in layered Weyl semimetal WTe$_2$ at 98.5 kbarNov 02 2017Layered transition metal dichalcogenide WTe$_2$ has recently attracted significant attention due to the discovery of an extremely large magnetoresistance, a predicted type-II Weyl semimetallic state, and the pressure-induced superconducting state. By ... More
Precise determination of stellar parameters of the ZZ Ceti and DAZ white dwarf GD 133 through asteroseismologyApr 16 2019An increasing number of white dwarf stars show atmospheric chemical composition polluted by heavy elements accreted from debris disk material. The existence of such debris disks strongly suggests the presence of one or more planet(s) whose gravitational ... More
Presence of Exotic Electronic Surface States in LaBi and LaSbJul 14 2016Nov 01 2016Extremely high magnetoresistance (XMR) in the lanthanum monopnictides La$X$ ($X$ = Sb, Bi) has recently attracted interest in these compounds as candidate topological materials. However, their perfect electron-hole compensation provides an alternative ... More
Quasilinear quantum magnetoresistance in pressure-induced nonsymmorphic superconductor CrAsDec 22 2016In conventional metals, modification of electron trajectories under magnetic field gives rise to a magnetoresistance that varies quadratically at low field, followed by a saturation at high field for closed orbits on the Fermi surface. Deviations from ... More
Study of the simplest realistic Higgs sector in quark-lepton symmetric modelsAug 11 1993A discrete symmetry between quarks and (generalized) leptons can exist in nature, and its spontaneous symmetry breaking scale can be as low as a few TeV. Such a discrete symmetry also has interesting implications for how electroweak symmetry is spontaneously ... More
Photoemission spectra of the t-J model in 1 and 2D: similarities and differencesFeb 26 1997We present an exact diagonalization study of the single particle spectral function in the 1D and 2D t-J model. By studying the scaling properties with J and t we find a simple building pattern in 1D and show that every spectral feature can be uniquely ... More
Hole pockets in the t-J modelJul 25 1994We present an exact diagonalization study of the electron momentum distribution n(k) in small clusters of t-J model for different hole concentrations and t/J. Structures in n(k) which were previously interpreted as a `large' Fermi surface are identified ... More
Spin bags in the doped t-J modelJun 24 1994We present a nonperturbative method for deriving a quasiparticle description of the low-energy excitations in the t-J model for strongly correlated electrons. Using the exact diagonalization technique we evaluated exactly the spectral functions of composite ... More
Inverse photoemission in strongly correlated electron systemsAug 25 1995Based on exact results for small clusters of 2D t-J model we demonstrate the existence of several distinct `channels' in its inverse photoemission (IPES) spectrum. Hole-like quasiparticles can either be annihilated completely, or leave behind a variable ... More