A5100695699- Advanced Condensed Matter Physics
- Topological Materials and Phenomena
- Graphene research and applications
- Iron-based superconductors research
- Physics of Superconductivity and Magnetism
- 2D Materials and Applications
- Rare-earth and actinide compounds
- Electronic and Structural Properties of Oxides
- Magnetic and transport properties of perovskites and related materials
- Quantum and electron transport phenomena
- Mobile Ad Hoc Networks
- Surface and Thin Film Phenomena
- Cooperative Communication and Network Coding
- Magnetic properties of thin films
- Advanced Chemical Physics Studies
- Organic and Molecular Conductors Research
- Magnetic Properties and Synthesis of Ferrites
- MXene and MAX Phase Materials
- Advanced MIMO Systems Optimization
- Iron oxide chemistry and applications
- Advanced ceramic materials synthesis
- Wireless Networks and Protocols
- Corporate Taxation and Avoidance
- Radiative Heat Transfer Studies
- Calibration and Measurement Techniques
Ajou University
2023-2024
Korea Advanced Institute of Science and Technology
2002-2024
The University of Tokyo
2011-2023
Institute for Solid State Physics and Optics
2023
Kwangwoon University
2021
Yonsei University
2020
Korea Institute of Ceramic Engineering and Technology
2020
Korea Research Institute of Standards and Science
2019
Korea Institute of Science and Technology
2014
Kyoto University
2012-2014
We have performed scanning tunneling microscopy and differential conductance (dI/dV) mapping for the surface of three-dimensional topological insulator Bi(2)Se(3). The fast Fourier transformation applied to dI/dV image shows an electron interference pattern near Dirac node despite general belief that backscattering is well suppressed in bulk energy gap region. comparison present experimental result with theoretical band structures occurs through scattering between states continuum states.
With the growing number of large scale software projects, development and maintenance demands participation larger groups. Having a thorough understanding group developers is critical for improving quality reducing cost. In contrast to most commercial endeavors, in open source (OSS) projects enjoy more freedom organize contribute project their own working style. Their interactions through various means generate latent developer social network (DSN). We have observed that relationships these...
Electron scattering in the topological surface state (TSS) of insulator ${\mathrm{Bi}}_{1.5}{\mathrm{Sb}}_{0.5}{\mathrm{Te}}_{1.7}{\mathrm{Se}}_{1.3}$ was studied using quasiparticle interference observed by scanning tunneling microscopy. It found that not only 180\ifmmode^\circ\else\textdegree\fi{} backscattering but also a wide range angles 100\ifmmode^\circ\else\textdegree\fi{}--180\ifmmode^\circ\else\textdegree\fi{} are effectively prohibited TSS. This conclusion obtained comparing...
The technical evolution of angle-resolved photoemission spectroscopy (ARPES) in the late 90s played a pivotal role exploration electronic structures condensed matter systems. ARPES achieved numerous successes during this period, notably capturing first evidence unconventional d-wave symmetry superconducting gap cuprate superconductors. It also elucidated essential rules governing topological signatures materials, and an demonstrating engineered band atomically thin materials. These early...
Vertical charge order shapes the electronic properties in layered density wave (CDW) materials. Various stacking orders inevitably create nanoscale domains with distinct structures inaccessible to bulk probes. Here, characteristics of 1$T$-TaS$2$ are analyzed using scanning tunneling spectroscopy (STS) and functional theory (DFT) calculations. It is observed that Mott-insulating undergo a transition band-insulating restoring vertical dimerization CDWs. Furthermore, STS measurements covering...
Abstract This study presents precise measurements of the melting and freezing temperatures pure iron (Fe) using radiation thermometry, aimed at improving temperature calibration techniques based on International Temperature Scale 1990 (ITS-90, t90). A newly designed Fe cell, filled with 99.99% nominal purity suitable for both thermocouple was used to determine t90 liquidus transition. The transitions were measured a calibrated thermometer, emissivity corrections made copper cell identical...
4Hb-${\mathrm{TaS}}_{2}$ has been proposed to possess unconventional superconductivity with broken time-reversal symmetry due distinctive layered structure, featuring a heterojunction between 2D triangular Mott insulator and charge-density wave metal. However, since frustrated spin state in the correlated insulating layer is susceptible charge ordering carrier doping, it required investigate distribution driven by interlayer transfer understand its superconductivity. Here, we use...
Abstract Two-dimensional electrides can acquire topologically non-trivial phases due to intriguing interplay between the cationic atomic layers and anionic electron layers. However, experimental evidence of topological surface states has yet be verified. Here, via angle-resolved photoemission spectroscopy (ARPES) scanning tunnelling microscopy (STM), we probe magnetic Weyl ferromagnetic electride [Gd 2 C] 2+ ·2e − . In particular, presence cones Fermi-arc is demonstrated through photon...
Abstract For the accurate measurement of temperature in upper air by using radiosondes, one prerequisite is compensation solar radiation effects that cause sensor heating. The development at Korea Research Institute Standards and Science (KRISS) an simulator (UAS) can simulate reported. UAS independently control four environmental parameters: irradiance, temperature, pressure speed. An entire radiosonde be installed test chamber data transmitted remotely via antenna. Solar irradiance...
In this paper, we propose a novel on-demand quality-of-service (QoS) routing protocol, SBR [signal-to-interference (SIR) and bandwidth routing], which explicitly fulfills both SIR requirements from different multimedia users in ad hoc mobile networks. With SBR, reservation is made by allocating time slots ensured assigning adequate powers at the intermediate nodes between source destination. The power-assignment method used supports finding routes that satisfy as well reduces level of...
Structural and magnetic properties, the valence band structure of pure Co-doped (up to 33%) Fe3O4(100) films were investigated. Reconstruction surface is found be blocked by Co doping. Doped ions in Fe3O4 are a charge state 2 + substitute Fe2+ B site Fe3O4. All exhibit room temperature ferromagnetism. doping changes coercivity reduces saturation magnetization. The density states near Fermi level reduced due decrease site, which might responsible for conductivity magnetoresistance Verwey...
Abstract The valence band structure of well-ordered Fe 3 O 4 (0 0 1) films was investigated in situ by angle-resolved photoemission spectroscopy (ARPES) at room temperature (RT) and 90 K. A gap about 70 meV below the Fermi level ( E F ) can be observed K, suggesting a ‘metal–insulator’ transition. With reduced from RT to 2 p -derived features shown ARPES spectra change substantially. Meanwhile, feature near film K becomes 0.1 eV deeper than that RT. results are compared with recent...
We report the discovery of a new three-dimensional (3D) topological Dirac semimetal (TDS) material KZnBi, coexisting with naturally formed superconducting state on surface under ambient pressure. Using photoemission spectroscopy together first-principles calculations, 3D linear band dispersion is identified. The characteristic features massless fermions are also confirmed by magnetotransport measurements, exhibiting an extremely small cyclotron mass m*=0.012 m0 and high Fermi velocity...
We report the synthesis of ethylenediamine-intercalated NbSe2 and Li-ethylenediamine-intercalated MoSe2 single crystals with increased interlayer distances their electronic structures measured by means angle-resolved photoemission spectroscopy (ARPES). X-ray diffraction patterns transmission electron microscopy images confirm successful intercalation an increase in distance. ARPES measurement reveals that intercalated shows structure almost identical to monolayer NbSe2. Intercalated also...
In most charge density wave (CDW) systems of different material classes, ranging from traditional correlated in low-dimension to recent topological with Kagome lattice, superconductivity emerges when the system is driven toward quantum critical point (QCP) CDW via external parameters doping and pressure. Despite this rather universal trend, essential hinge between has not been established yet. Here, evidence coupling electron fluctuation reported, based on a temperature-...
Surface states of platinum-induced atomic nanowires on a germanium (0 0 1) surface, which shows structural phase transition at 80 K, were studied by angle-resolved photoelectron spectroscopy (ARPES). We observed four one-dimensional metallic surface states, among which, two bands reported in our previous study (Yaji et al 2013 Phys. Rev. B 87 241413). One the newly-found is quasi-one-dimensional state and split into due to Rashba effect. Photoelectron intensity from one spin-polarized...
We report the signature of a strain-controlled topological phase transition in electronic structure quasi-one-dimensional superconductor ${\mathrm{TaSe}}_{3}$. Using angle-resolved photoemission spectroscopy and first-principles calculation, ${\mathrm{TaSe}}_{3}$ is identified to be weak insulator which has topologically nontrivial surface states only at allowed planes. Under uniaxial tensile strain, Dirac point state emerge on originally forbidden $(10\overline{1})$ plane, demonstrates...
Abstract Topological Dirac semimetals have emerged as a platform to engineer Berry curvature with time-reversal symmetry breaking, which allows access diverse quantum states in single material system. It is of interest realize such diversity that provides insight on correlation between and transport phenomena. Here, we report the transition anomalous Hall chiral fermion three-dimensional topological semimetal KZnBi, demonstrated by tuning direction flux curvature. Angle-dependent...
This letter deals with the issue of inefficient use radio resources due to frequent relay switchings in overhead constrained cooperative networks. A threshold-based switching protocol is proposed for enhanced achievable capacity and efficient resource management while preventing switchings. We derive under fading channels based on probability ergodic analysis. Also, optimal threshold value obtained from a convex optimization problem. Numerical simulation results reveal advantage over...
We report a combined infrared and angle-resolved photoemission study of the electronic response $\mathrm{S}{\mathrm{r}}_{3}{(\mathrm{I}{\mathrm{r}}_{1\ensuremath{-}x}\mathrm{R}{\mathrm{u}}_{x})}_{2}{\mathrm{O}}_{7}$ ($x=0$, 0.22, 0.34). The low-temperature optical conductivities three compounds exhibit characteristic feature effective total angular momentum ${J}_{\mathrm{eff}}=1/2$ antiferromagnetic Mott state. As temperature increases across ordering ${T}_{\mathrm{N}}$, indirect gap...