Results for "Myung Joon Han"

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Analytic continuation via domain-knowledge free machine learningJun 11 2018Mar 04 2019We present a machine-learning approach to a long-standing issue in quantum many-body physics, namely, analytic continuation. This notorious ill-conditioned problem of obtaining spectral function from imaginary time Green's function has been a focus of ... More
Charge density functional plus $U$ theory of LaMnO$_3$: Phase diagram, electronic structure, and magnetic interactionMar 01 2018We perform charge density functional theory plus $U$ calculation of LaMnO$_3$. While all the previous calculations were based on spin density functionals, our result and analysis show that the use of spin-unpolarized charge-only density is crucial to ... More
Calculating magnetic interactions in organic electridesApr 14 2018Jun 10 2018We present our calculation results for organic magnetic electrides. In order to identify the `cavity' electrons, we use maximally-localized Wannier functions and `empty atom' technique. The estimation of magnetic coupling is then performed based on magnetic ... More
Sub-room temperature ferromagnetism and its nature in VSe$_2$ monolayerJul 10 2019Magnetic van der Waals materials provide an ideal platform for exploring two-dimensional magnetism of technological and scientific importance. Among them, 1T-VSe$_2$ has been reported as one of the first room-temperature two-dimensional ferromagnets. ... More
Quasiparticle self-consistent GW study of cuprates: electronic structure, model parameters, and the two-band theory for TcApr 01 2015Despite decades of progress, an understanding of unconventional superconductivity still remains elusive. An important open question is about the material dependence of the superconducting properties. Using the quasiparticle self-consistent GW method, ... More
Reliability and applicability of magnetic force linear response theory: Numerical parameters, predictability, and orbital resolutionOct 20 2017We investigated the reliability and applicability of so-called magnetic force linear response method to calculate spin-spin interaction strengths from first-principles. We examined the dependence on the numerical parameters including the number of basis ... More
Magnetic force theory combined with quasi-particle self-consistent GW methodFeb 21 2019We report a successful combination of magnetic force linear response theory with quasiparticle self-consistent GW method. The self-consistently determined wavefunctions and eigenvalues can just be used for the conventional magnetic force calculations. ... More
Charge density functional plus $U$ calculation of lacunar spinel GaM$_4$Se$_8$ (M = Nb, Mo, Ta, and W)Jan 03 2019Charge density functional plus $U$ calculations are carried out to examine the validity of molecular $J_\text{eff}$=1/2 and 3/2 state in lacunar spinel GaM$_4$X$_8$ (M = Nb, Mo, Ta, and W). With LDA (spin-unpolarized local density approximation)$+U$, ... More
Model-mapped RPA for determining the effective Coulomb interactionJul 28 2016Feb 20 2017We present a new method to obtain interaction part of a model Hamiltonian from the result of the first-principles calculation. The effective interaction contained in the model is determined based on the random phase approximation (RPA). In contrast to ... More
Anomalous behavior of the quasi-one-dimensional quantum material Na$_{2}$OsO$_{4}$ at high pressureDec 15 2018Feb 20 2019Na$_{2}$OsO$_{4}$ is an unusual quantum material that, in contrast to the common 5${d}^{2}$ oxides with spins = 1, owns a magnetically silent ground state with spin = 0 and a band gap at Fermi level attributed to a distortion in the OsO$_{6}$ octahedral ... More
Deep Wide Field BVI CCD Photometry of the Sextans Dwarf Spheroidal GalaxyAug 27 2003We present deep wide field $VI$ CCD photometry of the Sextans dwarf spheroidal galaxy (dSph) in the Local Group, covering a field of 42' x 28' located at the center of the galaxy. Color-magnitude diagrams of the Sextans dSph show well-defined red giant ... More
The effect of double counting, spin density, and Hund interaction in the different DFT+$U$ functionalsSep 11 2017Jun 20 2018A systematic comparative study has been performed to better understand DFT$+U$ (density functional theory + $U$) method. We examine the effect of choosing different double counting and exchange-correlation functionals. The calculated energy distribution ... More
Magnetic ground state of SrRuO$_3$ thin film and applicability of standard first-principles approximations to metallic magnetismFeb 28 2017Jun 21 2017A systematic first-principles study has been performed to understand the magnetism of thin film SrRuO$_3$ which lots of research efforts have been devoted to but no clear consensus has been reached about its ground state properties. The relative t$_{2g}$ ... More
Comparative study of DFT+$U$ functionals for non-collinear magnetismFeb 27 2018Jun 11 2018We performed comparative analysis for DFT+$U$ functionals to better understand their applicability to non-collinear magnetism. Taking LiNiPO$_4$ and Sr$_2$IrO$_4$ as examples, we investigated the results out of two formalisms based on charge-only density ... More
Effects of spin-orbit interaction on magnetic and electronic structures in antiferromagnetic LaFeAsOAug 05 2010Dec 27 2016Magnetic and electronic structures in LaFeAsO in the single-stripe-type antiferromagnetic (AFM) phase are studied using first-principles density-functional calculations including the spin-orbit interaction. We show that the longitudinal ordering (LO) ... More
The nature of the SDSS galaxies in various classes based on morphology, colour and spectral features - II. Multi-wavelength propertiesSep 21 2009Sep 22 2009We present a multi-wavelength study of the nature of the SDSS galaxies divided into fine classes based on their morphology, colour and spectral features. The SDSS galaxies are classified into early-type and late-type; red and blue; passive, HII, Seyfert ... More
Maximum Quantum Entropy MethodApr 05 2018Maximum entropy method for analytic continuation is extended by introducing quantum relative entropy. This new method is formulated in terms of matrix-valued functions and therefore invariant under arbitrary unitary transformation of input matrix. As ... More
Structure, strain, and control of ground state property in LaTiO$_3$/LaAlO$_3$ superlatticeNov 29 2013Using first-principles density functional theory calculations, we examined the ground state property of LaTiO$_3$/LaAlO$_3$ superlattice. Total energy calculations, taking account of the structural distortions, $U$ dependence, and exchange correlation ... More
Spin moment formation and reduced orbital polarization in LaNiO$_3$/LaAlO$_3$ superlattice: LDA+U studyJan 25 2012Density functional band calculations have been performed to study LaNiO$_3$/LaAlO$_3$ superlattices. Motivated by recent experiments reporting the magnetic and metal-insulator phase transition as a function of LaNiO$_3$ layer thickness, we examined the ... More
Doping Driven ($π, 0$) Nesting and Magnetic Properties of Fe$_{1+x}$Te SuperconductorsMar 17 2009Apr 07 2009To understand newly discovered superconductivity in Fe--based systems, we investigate electronic structure and magnetic properties of Fe$_{1+x}$Te using first--principles density functional calculations. While the undoped FeTe has the same Fermi surface ... More
Electronic structure and orbital polarization of LaNiO$_3$ with a reduced coordination and under strain: first-principles studyMay 26 2011Sep 23 2011First-principles density functional theory calculations have been performed to understand the electronic structure and orbital polarization of LaNiO$_3$ with a reduced coordination and under strain. From the slab calculation to simulate [001] surface, ... More
Low-velocity anisotropic Dirac fermions on the side surface of topological insulatorsDec 31 2010Jan 10 2011We report anisotropic Dirac-cone surface bands on a side-surface geometry of the topological insulator Bi$_2$Se$_3$ revealed by first-principles density-functional calculations. We find that the electron velocity in the side-surface Dirac cone is anisotropically ... More
Quasiparticle self-consistent GW study of LaNiO$_3$ and LaNiO$_3$/LaAlO$_3$ superlatticeFeb 20 2014Using quasiparticle self-consistent $GW$ calculations we examined the electronic structure of LaNiO$_3$ and the LaNiO$_3$/LaAlO$_3$ superlattice. The effects of electron correlation in Ni-$d$ bands were reasonably well described without any {\it ad hoc} ... More
Effect of charge doping on the electronic structure, orbital polarization, and structural distortion in nickelate superlatticeJun 04 2013Jun 03 2015Using first-principles density functional theory calculations, we investigated the effect of charge doping in a LaNiO$_3$/SrTiO$_3$ superlattice. The detailed analysis based on two different simulation methods for doping clearly shows that the electronic ... More
Charge transfer, confinement, and ferromagnetism in LaMnO$_3$/LaNiO$_3$ (001)-superlatticeApr 24 2013Using first-principles density functional theory calculations, we investigated the electronic structure and magnetic properties of (LaMnO$_3$)$_m$/(LaNiO$_3$)$_n$ superlattices stacked along (001)-direction. The electrons are transferred from Mn to Ni, ... More
Fermi level density of states modulation without charge transfer in nickelate superlatticesApr 05 2013Jan 17 2014By using first-principles density functional theory calculations for (LaNiO3)m/(SrTiO3)n superlattices, we report a systematic way of electronic response to the interface geometry. It is found that Fermi level density of states of metallic nickelate layers ... More
Interplay between superconductivity and magnetism in one-unit-cell LaAlO3 capped with SrTiO3Jan 24 2018To form a conducting layer at the interface between the oxide insulators LaAlO3 and SrTiO3, the LaAlO3 layer on the SrTiO3 substrate must be at least four unit-cells-thick. The LaAlO3 SrTiO3 heterointerface thus formed exhibits various intriguing phenomena ... More
Competition between structural distortion and magnetic moment formation in fullerene C$_{20}$May 18 2009We investigated the effect of on-site Coulomb interactions on the structural and magnetic ground state of the fullerene C$_{20}$ based on density-functional-theory calculations within the local density approximation plus on-site Coulomb corrections (LDA+$U$). ... More
First Principle Simulations of Heavy Fermion Cerium Compounds Based on the Kondo LatticeApr 20 2009Aug 03 2009We propose a new framework for first-principle calculations of heavy-fermion materials. These are described in terms of the Kondo lattice Hamiltonian with the parameters extracted from a realistic density functional based calculation which is then solved ... More
Electronic Structure and Magnetic Properties of Iridate Superlattice SrIrO$_3$/SrTiO$_3$Feb 11 2014Motivated by an experimental report of iridate superlattices, we performed first-principle electronic structure calculations for SrIrO$_3$/SrTiO$_3$. Heterostructuring causes SrIrO$_3$ to become Sr$_2$IrO$_4$-like, and the system has the well-defined ... More
Small anisotropy of the lower critical field and $s_\pm$-wave two-gap feature in single crystal LiFeAsJul 28 2010Apr 13 2011The in- and out-of-plane lower critical fields and magnetic penetration depths for LiFeAs were examined. The anisotropy ratio $\gamma_{H_{c1}}(0)$ is smaller than the expected theoretical value, and increased slightly with increasing temperature from ... More
Analytic continuation via 'domain-knowledge free' machine learningJun 11 2018We present a machine-learning approach to a long-standing issue in quantum many-body physics, namely, analytic continuation. This notorious ill-conditioned problem of obtaining spectral function from imaginary time Green's function has been a focus of ... More
Magnetic proximity effect at Bi$_2$Se$_3$/EuS interface with broken inversion symmetryJul 23 2014We investigate a magnetic proximity effect on Dirac surface states of topological insulator (TI) induced by a Bi$_2$Se$_3$/EuS interface, using density-functional theory (DFT) and a low-energy effective model, motivated by a recent experimental realization ... More
Spin-orbital Entangled Molecular $j_{\rm eff}$ States in Lacunar Spinel CompoundsMar 06 2014Jun 07 2014The entanglement of the spin and orbital degrees of freedom through the spin-orbit coupling has been actively studied in condensed matter physics. In several iridium-oxide systems, the spin-orbital entangled state, identified by the effective angular ... More
Chemical control of orbital polarization in artificially structured transition-metal oxides: La2NiXO6 (X=B, Al, Ga, In) from first principlesApr 26 2010Oct 06 2010The application of modern layer-by-layer growth techniques to transition-metal oxide materials raises the possibility of creating new classes of materials with rationally designed correlated electron properties. An important step toward this goal is the ... More
Dimensional trend in CePt2In7, Ce-115 compounds, and CeIn3Apr 30 2010We present realistic Kondo-lattice simulation results for the recently-discovered heavy-fermion antiferromagnet CePt2In7 comparing with its three-dimensional counterpart CeIn3 and the less two-dimensional ones, Ce-115's. We find that the distance to the ... More
Quantified Degeneracy, Entropy and Metal-Insulator Transition in Complex Transition-Metal OxidesOct 01 2018Understanding complex correlated oxides and their phase transitions has long been a challenge. The difficulty largely arises from the intriguing interplay between multiple degrees of freedoms. While degeneracy can play an important role in determining ... More
Anomalous domain periodicity observed in ferroelectric PbTiO3 nanodots with 180o stripe domainsJan 15 2013PbTiO3-based nano-scale dots and tubes have received a great deal of attention owing to their potential applications to nonvolatile memories and multi-functional devices. As for the size effect of 180o stripe domains in ferroelectric thin films, there ... More
Electron-Hole Separation in Ferroelectric Oxides for Efficient Photovoltaic ResponsesNov 29 2017Despite their potential to exceed the theoretical Shockley-Queisser limit, ferroelectric photovoltaics (FPVs) have performed inefficiently due to their extremely low photocurrents. Incorporating Bi2FeCrO6 (BFCO) as the light absorber in FPVs has recently ... More
Anisotropy, Itineracy, and Magnetic Frustration in High-Tc Iron PnictidesOct 31 2008Mar 09 2009Using first-principle density functional theory calculations combined with insight from a tight-binding representation, dynamical mean field theory, and linear response theory, we have extensively investigated the electronic structures and magnetic interactions ... More
On the origin and the manipulation of ferromagnetism in Fe$_3$GeTe$_2$: defects and dopingsApr 09 2019To understand the magnetic properties of Fe$_3$GeTe$_2$, we performed the detailed first-principles study. Contrary to the conventional wisdom, it is unambiguously shown that Fe$_3$GeTe$_2$ is not ferromagnetic but antiferromagnetic carrying zero net ... More
Microscopic understanding of magnetic interactions in bilayer CrI$_3$Sep 05 2018Apr 09 2019We performed the detailed microscopic analysis of the inter-layer magnetic couplings for bilayer CrI$_3$. As the first step toward understanding the recent experimental observations and utilizing them for device applications, we estimated magnetic force ... More
Calculating branching ratio and spin-orbit coupling from first-principles: A formalism and its application to iridatesAug 23 2016We present a simple technique to calculate spin-orbit coupling, $\langle {\bf L}\cdot{\bf S} \rangle$, and branching ratio measured in x-ray absorption spectroscopy. Our method is for first-principles electronic structure calculation and its implementation ... More
Quasiparticle self-consistent GW calculation of Sr$_2$RuO$_4$ and SrRuO$_3$:Jul 31 2015Jan 25 2016Using quasiparticle self-consistent $GW$ calculations, we re-examined the electronic structure of Sr$_2$RuO$_4$ and SrRuO$_3$. Our calculations show that the correlation effects beyond the conventional LDA (local density approximation) and GGA (generalized ... More
Microscopic understanding of magnetic interactions in bilayer CrI$_3$Sep 05 2018Apr 02 2019We performed the detailed microscopic analysis of the inter-layer magnetic couplings for bilayer CrI$_3$. As the first step toward understanding the recent experimental observations and utilizing them for device applications, we estimated magnetic force ... More
Model-mapped RPA for determining the effective Coulomb interactionJul 28 2016We present a new method to obtain interaction part of a model Hamiltonian from the result of the first-principles calculation. The effective interaction contained in the model is determined based on the random phase approximation (RPA). In contrast to ... More
Microscopic understanding of magnetic interactions in bilayer CrI$_3$Sep 05 2018We performed the detailed microscopic analysis of the inter-layer magnetic couplings for bilayer CrI$_3$. As the first step toward understanding the recent experimental observations and utilizing them for device applications, we estimated magnetic force ... More
Collinear and non-collinear spin ground state of wurtzite CoOMay 27 2013Collinear and non-collinear spin structures of wurtzite phase CoO often appearing in nano-sized samples are investigated using first-principles density functional theory calculations. We examined the total energy of several different spin configurations, ... More
Direct theoretical evidence for weaker correlations in electron-doped and Hg-based hole-doped cupratesOct 26 2015Aug 27 2016Many important questions for high-$T_c$ cuprates are closely related to the insulating nature of parent compounds. While there has been intensive discussion on this issue, all arguments rely strongly on, or are closely related to, the correlation strength ... More
Tunable inverse topological heterostructure utilizing $(Bi_{1-x}In_{x})_{2}Se_{3}$Mar 02 2016In typical topological insulator (TI) systems the TI is bordered by a non-TI insulator, and the surrounding conventional insulators, including vacuum, are not generally treated as part of the TI system. Here, we implement the first material system where ... More
Transfer maps and nonexistence of joint determinantMar 31 2008Jun 29 2009Transfer Maps, sometimes called norm maps, for Milnor's $K$-theory were first defined by Bass and Tate (1972) for simple extensions of fields via tame symbol and Weil's reciprocity law, but their functoriality had not been settled until Kato (1980). On ... More
Near-field imaging beyond the probe aperture limitMar 05 2019Near-field scanning optical microscopy has been an indispensable tool for designing, characterizing and understanding the functionalities of diverse nanoscale photonic devices. As the advances in fabrication technology have driven the devices smaller ... More
A continuous-time approach to online optimizationJan 27 2014Feb 27 2014We consider a family of learning strategies for online optimization problems that evolve in continuous time and we show that they lead to no regret. From a more traditional, discrete-time viewpoint, this continuous-time approach allows us to derive the ... More
Lagrangian H-umbilical submanifolds in quaternion Euclidean spacesNov 05 2003The authors obtained the classification theorem for Lagrangian H-umbilical submanifolds in quaternion Euclidean spaces using the idea of quaternion extensors.
The explicit formula of flat Lagrangian H-umbilical submanifolds in quaternion Euclidean spacesNov 05 2003Using the idea of special Legendre curves, the authors obtained the explicit description of flat Lagrangian H-umbilical submanifolds in quaternion Euclidean spaces.
Chiral orbital-angular-momentum in the surface states of Bi2Se3Mar 04 2011Oct 11 2011Locking of the spin of a quasi-particle to its momentum in split bands of on the surfaces of metals and topological insulators (TIs) is understood in terms of Rashba effect where a free electron in the surface states feels an effective magnetic field. ... More
The existence, nonexistence and uniqueness of global positive coexistence of a nonlinear elliptic biological interacting modelAug 14 2003In this paper, we give a sufficient condition for the existence, nonexistence and uniqueness of coexistence of positive solutions to a rather general type of elliptic competition system.
Dirac-semimetal phase diagram of two-dimensional black phosphorusJun 14 2016Nov 24 2016Black phosphorus (BP), a layered van der Waals material, reportedly has a band gap sensitive to external perturbations and manifests a Dirac-semimetal phase when its band gap is closed. Previous studies were focused on effects of each perturbation, lacking ... More
MIRIS Paα Galactic Plane Survey. I. Comparison with IPHAS Hα in l = 96°-116°Sep 13 2018The Multipurpose InfraRed Imaging System (MIRIS) performed the MIRIS Pa{\alpha} Galactic Plane Survey (MIPAPS), which covers the entire Galactic plane within the latitude range of -3{\deg} < b < +3{\deg} at Pa{\alpha} (1.87 um). We present the first result ... More
Cyclotron Resonance in Strongly Magnetized Plasmas and Gamma Ray BurstDec 21 2011Nov 03 2012A plausible scenario for the gamma ray and the hard x-ray burst in a strongly magnetized plasma, based on the collective plasma maser instability, is proposed. The physical parameters with which this scenario becomes relevant are estimated. The attractive ... More
Idling Magnetic White Dwarf in the Synchronizing Polar BY Cam. The Noah-2 ProjectJun 10 2008Results of a multi-color study of the variability of the magnetic cataclysmic variable BY Cam are presented. The observations were obtained at the Korean 1.8m and Ukrainian 2.6m, 1.2m and 38-cm telescopes in 2003-2005, 56 observational runs cover 189 ... More
A wide-field photometric survey for extratidal tails around five metal-poor globular clusters in the Galactic haloDec 17 2009Wide-field deep gri images obtained with the Megacam of the Canada-France-Hawaii Telescope (CFHT) are used to investigate the spatial configuration of stars around five metal-poor globular cluster M15, M30, M53, NGC 5053, and NGC 5466, in a field-of-view ... More
Effects of spin-orbit interaction on the magnetic and electronic structure of antiferromagnetic LaFeAsOAug 05 2010Magnetic and electronic structures in LaFeAsO in the single-stripe-type antiferromagnetic (AFM) phase are studied using first-principles density-functional calculations including the spin-orbit interaction. We find that the longitudinal ordering (LO) ... More
The Nature of Blue Early-Type Galaxies in the Goods FieldsJun 24 2006We present a study of the nature of the blue early-type galaxies (BEGs) in the GOODS north and south fields using the GOODS HST/ACS archival data. Using visual inspection, we have selected 58 BEGs and 113 normal red early-type galaxies (REGs) in the sample ... More
The Exponent of a Polarizing Matrix Constructed from the Kronecker ProductAug 17 2011The asymptotic performance of a polar code under successive cancellation decoding is determined by the exponent of its polarizing matrix. We first prove that the partial distances of a polarizing matrix constructed from the Kronecker product are simply ... More
Intrinsic Band Gap and Electrically Tunable Flat Bands in Twisted Double Bilayer GrapheneMar 03 2019We present atomistic calculations on structural and electronic properties of twisted double bilayer graphene (TDBG) consisting of two sets of rotationally misaligned Bernal-stacked bilayer graphene. Obtained equilibrium atomic structures exhibit in-plane ... More
Density functional study of orbital-selective magnetism in FeAs-based superconductorsDec 10 2010Dec 26 2013We performed spin-polarized density functional calculations of lanthanide-series (Ln) iron oxypnictides LnFeAsO (Ln=La, Ce, Pr, Nd, Sm, and Gd) with constrained Fe magnetic moments, finding that in-plane dxy and out-of-plane dyz orbital characters are ... More
Graphyne: Hexagonal network of carbon with versatile Dirac conesDec 13 2011Mar 09 2013We study alpha, beta, and gamma graphyne, a class of graphene allotropes with carbon triple bonds, using a first-principles density-functional method and tight-binding calculation. We find that graphyne has versatile Dirac cones and it is due to remarkable ... More
Conformal field theory of dipolar SLE with the Dirichlet boundary conditionJul 16 2013We develop a version of dipolar conformal field theory based on the central charge modification of the Gaussian free field with the Dirichlet boundary condition and prove that correlators of certain family of fields in this theory are martingale-observables ... More
Theory of plasmon decay in dense plasmas and warm dense matterMar 07 2010Apr 27 2010The decay of the Langmuir waves in dense plasmas is not accurately predicted by the prevalent Landau damping theory. A dielectric function theory is introduced, predicting much higher damping than the Landau damping theory. This strong damping is in better ... More
Backward Raman compression of x-rays in metals and warm dense mattersFeb 08 2010Apr 26 2010Experimentally observed decay rate of the long wavelength Langmuir wave in metals and dense plasmas is orders of magnitude larger than the prediction of the prevalent Landau damping theory. The discrepancy is explored, and the existence of a regime where ... More
Alpha Chain Structures of ^{12}CMar 01 1999N-\alpha structures of light nuclei with axial symmetry are studied using relativistic Hartree approximation. Metastable excited states are searched in a configuration space which allows linear alpha chain structures. As a result, it is shown that ^{12}C ... More
Optimal Power and Range Adaptation for Green BroadcastingNov 27 2012Jul 07 2013Improving energy efficiency is key to network providers maintaining profit levels and an acceptable carbon footprint in the face of rapidly increasing data traffic in cellular networks in the coming years. The energy-saving concept studied in this paper ... More
Optimal Save-Then-Transmit Protocol for Energy Harvesting Wireless TransmittersApr 05 2012Feb 06 2013In this paper, the design of a wireless communication device relying exclusively on energy harvesting is considered. Due to the inability of rechargeable energy sources to charge and discharge at the same time, a constraint we term the energy half-duplex ... More
Wireless Communications with Unmanned Aerial Vehicles: Opportunities and ChallengesFeb 11 2016Wireless communication systems that include unmanned aerial vehicles (UAVs) promise to provide cost-effective wireless connectivity for devices without infrastructure coverage. Compared to terrestrial communications or those based on high-altitude platforms ... More
Similarity-based Random Survival ForestMar 04 2019Predicting the time to a clinical outcome for patients in intensive care units (ICUs) helps to support critical medical treatment decisions. The time to an event of interest could be, for example, survival time or time to recovery from a disease/ailment ... More
Sparse Stochastic BanditsJun 05 2017In the classical multi-armed bandit problem, d arms are available to the decision maker who pulls them sequentially in order to maximize his cumulative reward. Guarantees can be obtained on a relative quantity called regret, which scales linearly with ... More
Pressure-Induced Confined Metal from the Mott Insulator Sr3Ir2O7May 24 2016The spin-orbit Mott insulator Sr3Ir2O7 provides a fascinating playground to explore insulator-metal transition driven by intertwined charge, spin, and lattice degrees of freedom. Here, we report high pressure electric resistance and resonant inelastic ... More
Direct experimental observation of the molecular Jeff=3/2 ground state in the lacunar spinel GaTa4Se8Aug 04 2017Oct 20 2017Strong spin-orbit coupling lifts the degeneracy of t2g orbitals in 5d transition-metal systems, leaving a Kramers doublet and quartet with effective angular momentum of Jeff = 1/2 and 3/2, respectively. These spin-orbit entangled states can host exotic ... More
A Novel High-Pressure Monoclinic Metallic Phase of V2O3Dec 26 2013Vanadium sesquioxide, V2O3, is a prototypical metal-to-insulator system where, in temperature-dependent studies, the transition always coincides with a corundum-to-monoclinic structural transition. As a function of pressure, V2O3 follows the expected ... More
Anomalous behavior of the quasi-one-dimensional quantum material Na$_{2}$OsO$_{4}$ at high pressureDec 15 2018Na$_{2}$OsO$_{4}$ is an unusual quantum material that, in contrast to the common 5${d}^{2}$ oxides with spins = 1, owns a magnetically silent ground state with spin = 0 and a band gap at Fermi level attributed to a distortion in the OsO$_{6}$ octahedral ... More
Polarity-tunable magnetic tunnel junctions based on ferromagnetism at oxide heterointerfacesJul 12 2017Complex oxide systems have attracted considerable attention because of their fascinating properties, including the magnetic ordering at the conducting interface between two band insulators, such as LaAlO3 (LAO) and SrTiO3 (STO). However, the manipulation ... More
Spectral Theory of Discrete ProcessesMar 19 2009We offer a spectral analysis for a class of transfer operators. These transfer operators arise for a wide range of stochastic processes, ranging from random walks on infinite graphs to the processes that govern signals and recursive wavelet algorithms; ... More
Entropy Encoding, Hilbert Space and Karhunen-Loeve TransformsJan 23 2007Aug 23 2007By introducing Hilbert space and operators, we show how probabilities, approximations and entropy encoding from signal and image processing allow precise formulas and quantitative estimates. Our main results yield orthogonal bases which optimize distinct ... More
A Kaczmarz algorithm for sequences of projections, infinite products, and applications to frames in IFS $L^{2}$ spacesApr 09 2019We show that an idea, originating initially with a fundamental recursive iteration scheme (usually referred as "the" Kaczmarz algorithm), admits important applications in such infinite-dimensional, and non-commutative, settings as are central to spectral ... More
Local Decorrelation For Improved DetectionJun 04 2014Nov 04 2014Even with the advent of more sophisticated, data-hungry methods, boosted decision trees remain extraordinarily successful for fast rigid object detection, achieving top accuracy on numerous datasets. While effective, most boosted detectors use decision ... More
"Photonic" cat states from strongly interacting matter wavesJun 24 2015May 11 2016We consider ultracold quantum gases of scalar bosons, residing in a coupling strength--density regime in which they constitute a twofold fragmented condensate trapped in a single well. It is shown that the corresponding quantum states are, in the appropriate ... More
Hexagonal Indium Double Layer on Si(111)-($\sqrt{7}\times\sqrt{3})$Mar 23 2015Density-functional calculations are used to verify the atomic structure of the hexagonal In/Si(111)-($\sqrt{7}\times\sqrt{3}$) surface, which has been considered to represent an ultimate two-dimensional (2D) limit of metallic In overlayers. Contrary to ... More
Temperature Dependence of Thermal Conductivity of Polycrystalline Graphene: Thermally Enhanced Kapitza ConductanceApr 25 2013Graphene has drawn wide attention due to its exceptional thermal conductivity but complete understanding of thermal characteristics of polycrystalline graphene is still elusive to date. For the first time, herein, we have systematically studied the effect ... More
Robust inference for threshold regression modelsFeb 02 2017Nov 12 2018This paper is concerned with inference in threshold regression models when the practitioners do not know whether at the threshold point the true specification has a kink or a jump. We nest previous works that assume either continuity or discontinuity ... More
Discovery of Remote Star Clusters in the Halo of the Irregular Galaxy NGC 6822Oct 28 2005We report the discovery of three new star clusters in the halo of the Local Group dwarf irregular galaxy NGC 6822. These clusters were found in the deep images taken with the MegaPrime at the CFHT, covering a total field of 2 deg x 2 deg. The most remote ... More
AKARI Near-Infrared Spectroscopy of Luminous Infrared GalaxiesJul 07 2012We present the AKARI near-infrared (NIR; 2.5-5 micron) spectroscopic study of 36 (ultra)luminous infrared galaxies [(U)LIRGs] at z=0.01-0.4. We measure the NIR spectral features including the strengths of 3.3 micron polycyclic aromatic hydrocarbon (PAH) ... More
Structural and Correlation Effects in the Itinerant Insulating Antiferromagnetic Perovskite NaOsO3Oct 04 2012Mar 06 2013The orthorhombic perovskite NaOsO3 undergoes a continuous metal-insulator transition (MIT), accompanied by antiferromagnetic (AFM) order at T_N=410 K, suggested to be an example of the rare Slater (itinerant) MIT. We study this system using ab initio ... More
The Connection between Star-Forming Galaxies, AGN Host Galaxies and Early-Type Galaxies in the SDSSApr 18 2007Jun 29 2007We present a study of the connection between star-forming galaxies, AGN host galaxies, and normal early-type galaxies in the Sloan Digital Sky Survey (SDSS). Using the SDSS DR5 and DR4plus data, we select our early-type galaxy sample in the color versus ... More
AKARI Near-Infrared Spectroscopy of SDSS-Selected Blue Early-Type GalaxiesJul 03 2010A near-infrared (NIR; 2.5 - 4.5 micron) spectroscopic survey of SDSS(Sloan Digital Sky Survey)-selected blue early-type galaxies (BEGs) has been conducted using the AKARI. The NIR spectra of 36 BEGs are secured, which are well balanced in their star-formation(SF)/Seyfert/LINER ... More
Estimation of Individual Micro Data from Aggregated Open DataDec 19 2017In this paper, we propose a method of estimating individual micro data from aggregated open data based on semi-supervised learning and conditional probability. Firstly, the proposed method collects aggregated open data and support data, which are related ... More
The nature of the SDSS galaxies in various classes based on morphology, colour and spectral features -- I. Optical propertiesJul 01 2008We present a comprehensive study of the nature of the SDSS galaxies divided into various classes based on their morphology, colour, and spectral features. The SDSS galaxies are classified into early-type and late-type; red and blue; passive, HII, Seyfert, ... More
The nature of the Sloan Digital Sky Survey galaxies in various classes based on morphology, colour and spectral features - III. EnvironmentsNov 23 2009Nov 30 2009We present a study on the environments of the SDSS galaxies divided into fine classes based on their morphology, colour and spectral features. The SDSS galaxies are classified into early-type and late-type; red and blue; passive, HII, Seyfert and LINER, ... More
Cellular Automaton Based Simulation of Large Pedestrian Facilities - A Case Study on the Staten Island Ferry TerminalsSep 11 2017Current metropolises largely depend on a functioning transport infrastructure and the increasing demand can only be satisfied by a well organized mass transit. One example for a crucial mass transit system is New York City's Staten Island Ferry, connecting ... More
Graph 4-braid groups and Massey productsJul 14 2014We first show that the braid group over a graph topologically containing no $\Theta$-shape subgraph has a presentation related only by commutators. Then using discrete Morse theory and triple Massey products, we prove that a graph topologically contains ... More