Results for "T. K. Kim"

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Quantum estimation of magnetic-field gradient using W-stateSep 16 2013Jul 18 2014We study the precision limits of detecting a linear magnetic-field gradient by using W-states in the presence of different types of noises. We consider to use an atomic spin chain for probing the magnetic-field gradient, where a W-state is prepared. We ... More
Room-Temperature Ferromagnetism in Co-Doped TiO$_2$ Anatase: Role of Interstitial CoJun 15 2003TiO$_2$ anatase doped with Co has been recently reported to exhibit room-temperature ferromagnetism. $Ab$ $initio$ study on substitutional Co doping, however, yielded much larger magnetic moment for Co than experiment. Our calculations based on density-functional ... More
Structural, electronic, and magnetic properties of a ferromegnetic semiconductor: Co-doped TiO$_2$ rutileJun 15 2003Room-temperature ferromagnetism has been recently discovered in Co-doped TiO$_2$ rutile. Our $ab$ $initio$ density-functional theory investigations show that the substitutional Co ions incorporated into TiO$_2$ rutile tend to cluster and then the neighboring ... More
Extended Optical Model Analyses of Elastic Scattering and Fusion Cross Sections for 6Li + 208Pb System at Near-Coulomb-Barrier Energies by using Folding PotentialDec 13 2006Based on the extended optical model approach in which the polarization potential is decomposed into direct reaction (DR) and fusion parts, simultaneous $\chi^{2}$ analyses are performed for elastic scattering and fusion cross section data for the $^{6}$Li+$^{208}$Pb ... More
Extended Optical Model Analyses of Elastic Scattering and Fusion Cross Section Data for the 7Li+208Pb System at Near-Coulomb-Barrier Energies using the Folding PotentialJun 05 2007Simultaneous $\chi^{2}$ analyses previously made for elastic scattering and fusion cross section data for the $^{6}$Li+$^{208}$Pb system is extended to the $^{7}$Li+$^{208}$Pb system at near-Coulomb-barrier energies based on the extended optical model ... More
Extended Optical Model Analyses of Elastic Scattering and Fusion Cross Section Data for the 9Be+28Si, 144Sm, and 208Pb Systems at Near-Coulomb-Barrier Energies using Double Folding PotentialJul 09 2008Mar 14 2010Based on the extended optical model with the double folding potential, in which the polarization potential is decomposed into direct reaction (DR) and fusion parts, simultaneous $\chi^{2}$ analyses are performed of elastic scattering and fusion cross ... More
Neutral-current Neutrino-nucleus Scattering in Quasielastic RegionJul 10 2007Jul 20 2007The neutral-current neutrino-nucleus scattering is calculated through the neutrino-induced knocked-out nucleon process in the quasielastic region by using a relativistic single particle model for the bound and continuum states. The incident energy range ... More
The Modified q-Euler numbers and polynomialsFeb 18 2007In the recent paper the interesting q-Euler numbers and polynomials introduced in JMAA. The purpose of this paper is to construct the modified q-Euler numbers and polynomiasl. Finally we will give the interesting many identities related to these numbers ... More
A note on q-Volkenborn integrationJun 01 2005In this paper, we construct the new $q$-analogue of the ordinary Euler numbers and polynomials by using the $q$-Volkenborn integrals.
Two-pion-exchange contributions to the pp\to ppπ^0 reactionApr 11 2007Apr 17 2007Our previous study of the near-threshold pp\to pp\pi^0 reaction based on a hybrid nuclear effective field theory is further elaborated by examining the momentum dependence of the relevant transition operators. We show that the two-pion exchange diagrams ... More
Chiral-induced switching of antiferromagnet spins in a confined nanowireNov 06 2018In the development of spin-based electronic devices, one steady issue is the manipulation of the magnetic state and its magnetic texture with high speed and low power consumption. Research has focused on the current-induced spin orbit torque (SOT) based ... More
Chiral-induced switching of antiferromagnet spins in a confined nanowireNov 06 2018Mar 07 2019In the development of spin-based electronic devices, a particular challenge is the manipulation of the magnetic state with high speed and low power consumption. Although research has focused on the current-induced spin-orbit torque based on strong spin-orbit ... More
Bottomonium Decay Matrix Elements from Lattice QCD with Two Light QuarksJul 13 2001Jan 10 2002We calculate the long-distance matrix elements for the decays of the Upsilon (eta_b) and chi_b (h_b) states in lattice QCD with two flavors of light dynamical quarks. We relate the lattice matrix elements to their continuum counterparts through one-loop ... More
Decays rates for S- and P-wave bottomoniumDec 01 1994We use the Bodwin-Braaten-Lepage factorization scheme to separate the long- and short-distance factors that contribute to the decay rates of $\Upsilon$, $\eta_b$ (S-wave) and $\chi_b$,$h_b$ (P-wave). The long distance matrix elements are calculated on ... More
Reanalysis of near-infrared extragalactic background light based on the IRTS observationJan 07 2015May 20 2015We reanalyze data of near-infrared background taken by Infrared Telescope in Space (IRTS) based on up-to-date observational results of zodiacal light, integrated star light and diffuse Galactic light. We confirm the existence of residual isotropic emission, ... More
Polaron Absorption in a Perovskite Manganite La0.7Ca0.3MnO3Apr 16 1998Temperature dependent optical conductivity spectra of a La0.7Ca0.3MnO3 (LCMO) sample were measured. In the metallic regime at very low temperatures, they clearly showed two types of absorption features, i.e., a sharp Drude peak and a broad mid-infrared ... More
Symmetry p-adic invariant integral on Z_p for Bernoulli and euler polynomialsDec 02 2007The main purpose of this paper is to investigate several further interesting properties of symmetry for the p-adic invariant integral on Z_p.
Two-pion-exchange and other higher-order contributions to the $pp\to ppπ^0$ reactionOct 15 2008Jul 02 2009Much effort has been invested on effective-field-theoretical studies of the near-threshold NN \to NN\pi reactions and, in order to deal with the rather large three-momentum transfers involved, the momentum counting scheme was proposed as an alternative ... More
Use of V_{low-k} in a chiral-perturbation-theory description of the $pp\to ppπ^0$ reactionSep 01 2005Oct 19 2005Previously, the near-threhold $pp\to pp\pi^0$ reaction was studied with the use of transition operators derived from chiral perturbation theory ($\chi$PT) and the nuclear wave functions generated by high-precision phenomenological potentials. A conceptual ... More
Lattice Calculation of Quarkonium Decay Matrix ElementsSep 16 1996We calculate the NRQCD matrix elements for the decays of the lowest-lying S- and P-wave states of charmonium and bottomonium in quenched lattice QCD. We also compute the one-loop relations between the lattice and continuum matrix elements.
Quarkonium Decay Matrix Elements from Quenched Lattice QCDMay 20 1996Jul 30 1996We calculate the long-distance matrix elements for the decays of the lowest-lying S- and P-wave states of charmonium and bottomonium in quenched lattice QCD, using a nonrelativistic formulation for the heavy quarks. (The short-distance coefficients are ... More
A note on the alternating sums of powers of consecutive q-integersApr 10 2006In this paper we construct a new q-Euler numbers and polynomials. By using these numbers and polynomials, we give the interesting formulae related to alternating sums of powers of consecutive q-integers following an idea due to Euler.
Note on multiple q-zeta functionsDec 30 2009In this paper, we construct the alternating multiple q-zeta function(= Multiple Euler q-zeta function) and investigate their properties. Finally, we give some interesting functional eauations related to q-Euler polynomials.
A note on the generalized Euler numbers and polynomialsJul 28 2009In this paper, we derive some interesting symmetric properties for the geenralized Euler numbers and polynomials.
On the q-Euler numbers and polynomials with weight 0Oct 10 2011The purpose of this paper is to investigate some properties of q-Euler numbers and polynomials with weight 0. From those q-Euler numbers with weight 0, we derive some identities on the q-Euler numbers and polynomials with weight 0.
p-adic l-functions and sums of powersMay 27 2006The purpose of this paper is to give the explicit formulae of p-adic l-functions and sums of powers which are related to Euler numbers.
A note on the alternating sums of powers of consecutive integersAug 13 2005Following an idea due to Euler, we evaluate the alternating sums of powers of consrcutive integers.
Analytic Continuation of q-Euler numbers and polynomialsJan 03 2008In this paper we study that the $q$-Euler numbers and polynomials are analytically continued to $E_q(s)$. A new formula for the Euler's $q$-Zeta function $\zeta_{E,q}(s)$ in terms of nested series of $\zeta_{E,q}(n)$ is derived. Finally we introduce the ... More
Algebraic charge liquidsJun 15 2007Dec 03 2007High temperature superconductivity emerges in the cuprate compounds upon changing the electron density of an insulator in which the electron spins are antiferromagnetically ordered. A key characteristic of the superconductor is that electrons can be extracted ... More
Degenerate Cauchy numbers and polynomials of the second kindAug 24 2017Recently, degenerate Cauchy numbers and polynomials are introduced in [10]. In this paper, we study the degenerate Cauchy numbers and polynomials which are different from the previous degenerate Cauchy numbers and polynomials. In addition, we give some ... More
Identities involving Frobenius-Euler polynomials arising from non-linear differential equationsJan 24 2012In this paper we consider non-linear differential equations which are closely related to the generating functions of Frobenius-Euler polynomials. From our non-linear differential equations, we derive some new identities between the sums of products of ... More
q-Bernstein polynomials, q-Stirling numbers and q-Bernoulli polynomialsAug 26 2010In this paper, we give new identities involving Phillips q-Bernstein polynomials and we derive some interesting properties of q-Berstein polynomials associated with q-Stirling numbers and q-Bernoulli polynomials.
Note on q-Dedekind type sums related to q-Euler polynomialsJul 29 2009it is the purpose of this paper to construct a p-adic continuous function for an odd prime to contain a p-adic q-analogue of higher order Dedekind type sums related to q-Euler polynomials and numbers.
Spin-transfer-torque through antiferromagnetic IrMnNov 15 2014Feb 19 2015Spin-transfer-torque, a transfer of angular momentum between the electron spin and the local magnetic moments, is a promising and key mechanism to control ferromagnetic materials in modern spintronic devices . However, much less attention has been paid ... More
Effect of linear density of states on the quasi-particle dynamics and small electron-phonon coupling in graphiteAug 25 2007We obtained the spectral function of very high quality natural graphite single crystals using angle resolved photoelectron spectroscopy (ARPES). A clear separation of non-bonding and bonding bands and asymmetric lineshape are observed. The asymmetric ... More
Development of the Simulator for the Global Orbit Feedback System Using EPICSNov 05 2001Nov 09 2001We have carried out the basic research for the accelerator and tokamak control system based on the Experimental Physics and Industrial Control System (EPICS). We have used the process database and the state notation language (SNL) in the EPICS to develop ... More
Fractional Dynamical Behavior in Quantum Brownian MotionMar 29 2002The dynamical behavior for a quantum Brownian particle is investigated under a random potential of the fractional iterative map on a one-dimensional lattice. For our case, the quantum expectation values can be obtained numerically from the wave function ... More
Test of CsI(Tl) crystals for the Dark Matter SearchOct 28 1999Searches for weakly interacting massive particles(WIMP) can be based on the dete ction of nuclear recoil energy in CsI(Tl) crystals. We demonstrate that low energy gamma rays down to few keV is detected with CsI(Tl) crystal detector. A clear peak at 6 ... More
Switching local magnetization by electric-field-induced domain wall motionMar 29 2016Electric field effect on magnetism is an appealing technique for manipulating the magnetization at a low cost of energy. Here, we show that the local magnetization of the ultra-thin Co film can be switched by just applying a gate electric field without ... More
A fast programmable trigger for isolated cluster counting in the BELLE experimentNov 23 1999We have developed a fast programmable trigger processor board based on a field programmable gate array and a complex programmable logic device for use in the BELLE experiment. The trigger board accommodates 144 ECL input signals, 2 NIM input signals, ... More
Coercive fields in ultrathin BaTiO3 capacitorsSep 04 2006Thickness-dependence of coercive field (EC) was investigated in ultrathin BaTiO3 capacitors with thicknesses (d) between 30 and 5 nm. The EC appears nearly independent of d below 15 nm, and decreases slowly as d increases above 15 nm. This behavior cannot ... More
A Role of the Axial Vector Mesons on the Photon Production in Heavy Ion Collisions and Their Relevant DecaysAug 06 2001A role of the axial vector mesons, such as $K_1$ and $a_1$, on the emitted photon spectrum in hot hadronic matter is studied through the channels $\pi \rho \to a_1 \to \pi \gamma$ and $K \rho \to K_1 \to K \gamma$. They are shown to be dominant channels ... 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
The 2 to 24 micron source counts from the AKARI North Ecliptic Pole surveyAug 08 2014We present herein galaxy number counts of the nine bands in the 2-24 micron range on the basis of the AKARI North Ecliptic Pole (NEP) surveys. The number counts are derived from NEP-deep and NEP-wide surveys, which cover areas of 0.5 and 5.8 deg2, respectively. ... More
Low scale Seesaw model and Lepton Flavor Violating Rare B DecaysDec 02 2005Dec 09 2005We study lepton flavor number violating rare B decays, $b \to s l_h^{\pm} l_l^{\mp}$, in a seesaw model with low scale singlet Majorana neutrinos motivated by the resonant leptogenesis scenario. The branching ratios of inclusive decays $ b \to s l_h^{\pm} ... 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
First-Principles Calculation of Thermal Transport in the Metal/Graphene SystemMar 27 2013Thermal properties in the metal/graphene (Gr) systems are analyzed by using an atomistic phonon transport model based on Landauer formalism and first-principles calculations. The specific structures under investigation include chemisorbed Ni(111)/Gr, ... More
Neutralino Dark Matter in minimal supersymmetric standard model with natural light Higgs sectorApr 18 2008Sep 11 2008We study the neutralino relic density in the minimal supersymmetric standard model with natural light Higgs sector in which all Higgs masses, the supersymmetry (SUSY) breaking parameters, and the higgsino mass parameter mu are of order the weak scale. ... More
Evidence for multiple superconducting gaps in optimally doped BaFe$_{1.87}$Co$_{0.13}$As$_{2}$ from infrared spectroscopyDec 01 2009Jun 08 2010We performed combined infrared reflection and ellipsometry measurements of the in-plane optical reponse of single crystals of the pnictide high temperature superconductor BaFe$_{1.87}$Co$_{0.13}$As$_{2}$ with $T_{c}$ = 24.5 K. We observed characteristic ... More
Structural evolution of bismuth sodium titanate induced by A-site non-stoichiometry: Neutron powder diffraction studiesSep 04 2015We performed neutron powder diffraction measurements on (Bi$_{0.5}$Na$_{0.5+x}$)TiO$_3$ and (Bi$_{0.5+y}$Na$_{0.5}$)TiO$_3$ to study structural evolution induced by the non-stoichiometry. Despite the non-stoichiometry, the local structure ($r$$\leq$ 3.5 ... More
Optical Evidence of Multiphase Coexistence in Single Crystalline (La,Pr,Ca)MnO3Mar 05 2002We investigated temperature (T)- and magnetic field-dependent optical conductivity spectra (\s\w) of a La_5/8-yPr_yCa_3/8MnO_3 (y~0.35) single crystal, showing intriguing phase coexistence at low T. At T_C < T < T_CO, a dominant charge-ordered phase produces ... More
Measurement Limits to 134Cs Concentration in SoilJan 10 2009Dec 22 2011We investigate the caesium concentrations in soils in mountain areas near Gori nuclear power plant in Korea, focusing on the measurement limits to the 134Cs. In order to lower the minimum detectable amount (MDA) of activity for the 134Cs, we have used ... More
Barnes' multiple Bernoulli and poly-Bernoulli mixed-type polynomialsDec 27 2013In this paper, we consider Barnes' multiple Bernoulli and poly-Bernoulli mixed-type polynomials. From the properties of Sheffer sequences of these polynomials arising from umbrral calculus, we derive new and interesting identities.
Dielectric constants of Ir, Ru, Pt, and IrO2: Contributions from bound chargesJul 03 2006Nov 22 2006We investigated the dielectric functions $\epsilon$($\omega$) of Ir, Ru, Pt, and IrO$_2$, which are commonly used as electrodes in ferroelectric thin film applications. In particular, we investigated the contributions from bound charges $\epsilon^{b}$($\omega$), ... More
Spin/Orbital Pattern-Dependent Polaron Absorption in Nd(1-x)Sr(x)MnO3Mar 09 2002We investigated optical properties of Nd(1-x)Sr(x)MnO3 (x= 0.40, 0.50, 0.55, and 0.65) single crystals. In the spin/orbital disordered state, their conductivity spectra look quite similar, and the strength of the mid-infrared absorption peak is proportional ... More
X-ray induced electronic structure change in CuIr$_2$S$_4$Apr 29 2011The electronic structure of CuIr$_2$S$_4$ has been investigated using various bulk-sensitive x-ray spectroscopic methods near the Ir $L_3$-edge: resonant inelastic x-ray scattering (RIXS), x-ray absorption spectroscopy in the partial fluorescence yield ... More
Angle-resolved photoemission spectroscopy of Co-based boride superconductor LaCo1.73Fe0.27B2Jul 06 2012We have performed angle-resolved photoemission spectroscopy of Co-based boride superconductor LaCo1.73Fe0.27B2 (Tc = 4.1 K), which is isostructural to the 122-type Fe-pnictide superconductor with the pnictogen atom being replaced with boron. We found ... More
Wavelength- and material-dependent absorption in GaAs and AlGaAs microcavitiesOct 23 2006Dec 15 2006The quality factors of modes in nearly identical GaAs and Al_{0.18}Ga_{0.82}As microdisks are tracked over three wavelength ranges centered at 980 nm, 1460 nm, and 1600 nm, with quality factors measured as high as 6.62x10^5 in the 1600-nm band. After ... More
Large Enhancement of the Photoluminescence Emission of Photoexcited Undoped GaAs Quantum Wells Induced by an Intense Single-Cycle Terahertz PulseJul 16 2013Intense terahetz (THz) pulses induce a photoluminescence (PL) flash from undoped high-quality GaAs/AlGaAs quantum wells under continuous wave laser excitation. The number of excitons increases 10000-fold from that of the steady state under only laser ... More
Time-resolved observation of coherent excitonic nonlinear response with a table-top narrowband THz pulse waveDec 03 2015By combining a tilted-pulse-intensity-front scheme using a LiNbO3 crystal and a chirped-pulse-beating method, we generated a narrowband intense terahertz (THz) pulse, which had a maximum electric field of more than 10 kV/cm at around 2 THz, a bandwidth ... More
Lepton Flavor Violation in SUSY GUT Model with Non-universal Sfermion MassesDec 29 2006Jan 09 2007We analyze lepton flavor violating $\tau \to \mu \gamma$ and $\mu \to e \gamma$ processes in SUSY GUT model in which sfermions have special mass spectrum. It is assumed that only third generation sfermions which are contained in ${\bf 10}(Q, U^c, E^c)$ ... More
Constraining population synthesis models via the binary neutron star populationApr 21 2005Jun 13 2005The observed sample of double neutron-star (NS-NS) binaries presents a challenge to population-synthesis models of compact object formation: the parameters entering into these models must be carefully chosen so as to match (i) the observed star formation ... More
Quantum Hall Charge Sensor for Single-Donor Nuclear Spin Detection in SiliconMay 06 2010May 12 2010We propose a novel optical and electrical hybrid scheme for the measurement of nuclear spin qubits in silicon. By combining the environmental insensitivity of the integer quantum Hall effect with the optically distinguishable hyperfine states of phosphorus ... More
Laguerre-Gaussian mode sorterMar 12 2018Aug 31 2018Light's spatial properties represent an infinite state space, making it attractive for applications requiring high dimensionality, such as quantum mechanics and classical telecommunications, but also inherently spatial applications such as imaging and ... More
Self-organized current transport through low angle grain boundaries in YBa$_2$Cu$_3$O$_{7-δ}$ thin films, studied magnetometricallyAug 16 2003The critical current density flowing across low angle grain boundaries in YBa$_2$Cu$_3$O$_{7-\delta}$ thin films has been studied magnetometrically. Films (200 nm thickness) were deposited on SrTiO$_3$ bicrystal substrates containing a single [001] tilt ... More
Far-infrared signature of the superconducting gap in intercalated graphite CaC6Apr 16 2008Apr 17 2008Terahertz reflectance spectra of the Ca-intercalated graphite CaC6 reveal a superconducting gap below 11K. The gap signature lacks a sharp onset to full reflectivity at 2Delta, but rather shows a distribution of gap values consistent with an anisotropic ... More
New detections of (sub)millimeter hydrogen radio recombination lines towards high-mass star-forming clumpsApr 19 2018Previous radio recombination line (RRL) observations of dust clumps identified in the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) have led to the detection of a large number of RRLs in the 3mm range. Here, we aim to study their excitation ... More
Modeling the Solar Wind at the Ulysses, Voyager, and New Horizons SpacecraftAug 27 2016The outer heliosphere is a dynamic region shaped largely by the interaction between the solar wind and the interstellar medium. While interplanetary magnetic field and plasma observations by the Voyager spacecraft have significantly improved our understanding ... More
Precision spectroscopy with two correlated atomsJun 21 2007Nov 19 2007We discuss techniques that allow for long coherence times in laser spectroscopy experiments with two trapped ions. We show that for this purpose not only entangled ions prepared in decoherence-free subspaces can be used but also a pair of ions that are ... More
A Solution for Little Hierarchy Problem and b --> s gammaSep 07 2006May 21 2007We show that all the parameters which destabilize the weak scale can be taken around the weak scale in the MSSM without conflicting with the SM Higgs mass bound set by LEP experiment. The essential point is that if the lightest CP-even Higgs h in the ... More
Double superconducting transition and low-temperature specific heat study of Pr(Os$_{1-x}$Ru$_x$)$_4$Sb$_{12}$Nov 04 2005The double superconducting transition in PrOs$_4$Sb$_{12}$, first observed in specific heat $C(T)$ measurements of single crystal samples, is the subject of an in-depth study. The double superconducting transitions of a batch of single crystals were measured ... More
Topological surface state under graphene for two-dimensional spintronics in airApr 17 2011Spin currents which allow for a dissipationless transport of information can be generated by electric fields in semiconductor heterostructures in the presence of a Rashba-type spin-orbit coupling. The largest Rashba effects occur for electronic surface ... More
Charge Ordering Fluctuation and Optical Pseudogap in La$_{1-x}$Ca$_{x}$MnO$_{3}$Mar 07 2002Optical spectroscopy was used to investigate the optical gap (2$\Delta $) due to charge ordering (CO) and related pseudogap developments with x and temperature (T) in La$_{1-x}$Ca$_{x}$MnO$_{3}$ (0.48 <= x <= 0.67). Surprisingly, we found 2$\Delta $/k_{B}T_{CO} ... More
CP asymmetries of B to phi K_S and B to eta' K_S in SUSY GUT Model with Non-universal Sfermion MassesMar 31 2008Jan 31 2009We analyze CP asymmetries of B \to \phi K_S and B \to \eta' K_S in a supersymmetric grand unified theory in which only the third generation sfermions contained in 10(Q, U^c, E^c) of SU(5) can have a different mass from the others. One of the advantages ... More
Higgs boson decay into heavy quarks and heavy leptons: higher order correctionsDec 02 2009Theoretical predictions for the decay width of Standard Model Higgs boson into bottom quarks and tau-leptons, in the case when M_H< 2M_W, are briefly reviewed. The effects of higher order perturbative QCD (up to alpha_s^4-level) and QED corrections are ... More
Identities involving values of Bernstein, q-Bernoulli and q-Euler polynomialsJan 13 2011In this paper we give some relation involving values of q-Bernoulli, q-Euler and Bernstein polynomials. From these relations, we obtain some interesting identities on the q-Bernoulli, q-Euler and Bernstein polynomials.
High-Energy Continuum of Magnetic Excitations in the Two-Dimensional Quantum Antiferromagnet Sr2CuO2Cl2Feb 13 2014We have measured the magnetic excitation spectrum of the model square-lattice spin-1/2 antiferromagnet $\rm Sr_2CuO_2Cl_2$ over a broad range of energy and momentum using high-resolution inelastic neutron scattering (INS). The magnon dispersion along ... More
Electron-phonon interaction via Pekar mechanism in nanostructuresMay 14 2004We consider an electron-acoustic phonon coupling mechanism associated with the dependence of crystal dielectric permittivity on the strain (the so-called Pekar mechanism) in nanostructures characterized by strong confining electric fields. The efficiency ... More
Fabrication and Electrical Properties of Pure VO2 Phase FilmsNov 27 2003Nov 29 2003We have grown VO2 thin films by laser ablation for electronic device applications. In obtaining the thin films of the pure VO2 phase, oxygen partial pressure is a critical parameter because vanadium oxides have several phases with the oxygen concentration. ... More
Bound Excitons in Sr$_{2}$CuO$_{3}$Jun 12 2008Oct 26 2008We investigated temperature dependent optical spectra of the one-dimensional chain compound Sr$_{2}$CuO$_{3}$. The charge transfer transition polarized along the chain direction shows a strongly asymmetric line shape as expected in one-dimensional extended ... More
Infrared Line Emission in the Interacting Region of Arp 244 (the Antennae): Colliding Molecular Cloud Complexes ?Jan 28 2001Feb 23 2001We report velocity-resolved spectroscopy of infrared hydrogen recombination lines in the interacting region of the Antennae galaxies (NGC 4038/4039). It generally has been assumed that the active star formation found there is due to the interaction of ... More
ATLASGAL-selected massive clumps in the inner Galaxy IV. Millimeter hydrogen recombination lines from associated HII regionsFeb 07 2017Observations of millimeter wavelength radio recombination lines (mm-RRLs) are used to search for HII regions in an unbiased way that is complementary to many of the more traditional methods previously used. We carried out targeted mm-RRL observations ... More
Strongly enhanced temperature dependence of the chemical potential in FeSeFeb 21 2017Employing a 10-orbital tight binding model, we present a new set of hopping parameters fitted directly to our latest high resolution angle-resolved photoemission spectroscopy (ARPES) data for the high temperature tetragonal phase of FeSe. Using these ... More
Modelling the Off-Shell Dependence of $π^{o}- η$ Mixing with Quark LoopsOct 02 1992It is shown that including form factors for the quark-pseudoscalar meson couplings of the Georgi-Manohar chiral quark model allows one to obtain the leading off-shell dependence of $\pi^{o}- \eta$ mixing (as predicted by chiral perturbation theory) from ... More
The Lyman-alpha Emission Line as a Cosmological ToolNov 13 2007This thesis deals with different aspects of a special kind of high redshift galaxy, namely Ly-alpha emitters. Ly-alpha emitters are galaxies found through their Ly-alpha emission, at redshifts larger than z >~ 2 where the emission line has been redshifted ... More
Minimax bounds for estimation of normal mixturesDec 20 2011Oct 21 2014This paper deals with minimax rates of convergence for estimation of density functions on the real line. The densities are assumed to be location mixtures of normals, a global regularity requirement that creates subtle difficulties for the application ... More
Doping Dependent Changes in Nitrogen 2$p$ States in the Diluted Magnetic Semiconductor Ga$_{1-x}$Cr$_{x}$NSep 30 2004We study the electronic structure of the recently discovered diluted magnetic semiconductor Ga$_{1-x}$Cr$_{x}$N ($x$ = 0.01-0.10). A systematic study of the changes in the $occupied$ and $unoccupied$ ligand (N) partial density of states (DOS) of the host ... More
Polarization Relaxation Induced by Depolarization Field in Ultrathin Ferroelectric BaTiO$_3$ CapacitorsJun 20 2005Oct 14 2005Time-dependent polarization relaxation behaviors induced by a depolarization field $E_{d}$ were investigated on high-quality ultrathin SrRuO$_{3}$/BaTiO$_{3}$/SrRuO$_{3}$ capacitors. The $E_d$ values were determined experimentally from an applied external ... More
Polarization Switching Dynamics Governed by Thermodynamic Nucleation Process in Ultrathin Ferroelectric FilmsMay 03 2006A long standing problem of domain switching process - how domains nucleate - is examined in ultrathin ferroelectric films. We demonstrate that the large depolarization fields in ultrathin films could significantly lower the nucleation energy barrier (U*) ... More
Quantum Oscillations of the Metallic Triangular-lattice Antiferromagnet PdCrO2Feb 16 2013We report the de Haas-van Alphen (dHvA) oscillations and first-principle calculations for triangular antiferromagnet PdCrO2 showing unconventional anomalous Hall effect (AHE). The dHvA oscillations in PdCrO2 reveal presence of several 2 dimensional Fermi ... More
Formation of mid-gap states and ferromagnetism in semiconducting CaB$_6$Oct 03 2003We present a consistent overall picture of the electronic structure and ferromagnetic interaction in CaB$_6$, based on our joint transport, optical, and tunneling measurements on high-quality {\em defect-controlled} single crystals. Pure CaB$_6$ single ... More
Sub-Cycle Optical Response Caused by Dressed State with Phase-Locked WavefunctionsNov 22 2016The coherent interaction of light with matter imprints the phase information of the light field on the wavefunction of the photon-dressed electronic state. Driving electric field, together with a stable phase that is associated with the optical probe ... More
Observational signatures of microlensing in gravitational waves at LIGO/Virgo frequenciesMar 11 2019Microlenses with typical stellar masses (a few ${\rm M}_{\odot}$) have traditionally been disregarded as potential sources of gravitational lensing effects at LIGO/Virgo frequencies, since the time delays are often much smaller than the inverse of the ... More
Fiske steps studied with flux-flow resistance oscillation in a narrow stack of Bi2Sr2CaCu2O8+d junctionsDec 27 2004Sep 01 2005We have experimentally investigated the fluxon dynamics in a narrow Bi2Sr2CaCu2O8+d stack with junction length L~1.8 um. As an evidence of high-frequency excitation by a collective cavity mode, under an (in-plane) external magnetic field, the current-voltage ... More
Nonlinear Force-Free Extrapolation of the Coronal Magnetic Field Based on the MHD Relaxation MethodNov 14 2013We develop a nonlinear force-free field (NLFFF) extrapolation code based on the magnetohydrodynamic (MHD) relaxation method. We extend the classical MHD relaxation method in two important ways. First, we introduce an algorithm initially proposed by cite{2002JCoPh.175..645D} ... More
Electron-Phonon Interactions in Bilayer Graphene: A First Principles ApproachNov 24 2010Density functional perturbation theory is used to analyze electron-phonon interaction in bilayer graphene. The results show that phonon scattering in bilayer graphene bears more resemblance with bulk graphite than monolayer graphene. In particular, electron-phonon ... More
Gate-tunable Memristive Phenonmena Mediated by Grain Boundaries in Single Layer MoS2Apr 06 2015Continued progress in high speed computing depends on breakthroughs in both materials synthesis and device architectures. The performance of logic and memory can be enhanced significantly by introducing a memristor, a two terminal device with internal ... More
Current-induced asymmetric magnetoresistance due to energy transfer via quantum spin-flip processMar 29 2016Current-induced magnetization excitation is a core phenomenon for next-generation magnetic nanodevices, and has been attributed to the spin-transfer torque (STT) that originates from the transfer of the spin angular momentum between a conduction electron ... More
Domain Switching Kinetics in Disordered Ferroelectric Thin FilmsApr 09 2007We investigated domain kinetics by measuring the polarization switching behaviors of polycrystalline Pb(Zr,Ti)O$_{3}$ films, which are widely used in ferroelectric memory devices. Their switching behaviors at various electric fields and temperatures could ... More
A Novel Method for the Solution of the Schroedinger Eq. in the Presence of Exchange TermsJan 29 2002In the Hartree-Fock approximation the Pauli exclusion principle leads to a Schroedinger Eq. of an integro-differential form. We describe a new spectral noniterative method (S-IEM), previously developed for solving the Lippman-Schwinger integral equation ... More