A5073627088- Graphene research and applications
- Electron and X-Ray Spectroscopy Techniques
- Topological Materials and Phenomena
- Advancements in Photolithography Techniques
- 2D Materials and Applications
- Advanced Condensed Matter Physics
- Multiferroics and related materials
- Magnetic properties of thin films
- Semiconductor materials and devices
- Electronic and Structural Properties of Oxides
- Physics of Superconductivity and Magnetism
- Mesoporous Materials and Catalysis
- Iron-based superconductors research
- Gas Sensing Nanomaterials and Sensors
- Inorganic Chemistry and Materials
- ZnO doping and properties
- Aerosol Filtration and Electrostatic Precipitation
- Transition Metal Oxide Nanomaterials
- Integrated Circuits and Semiconductor Failure Analysis
- Magnetic and transport properties of perovskites and related materials
- Surface and Thin Film Phenomena
- Semiconductor materials and interfaces
- Quantum and electron transport phenomena
- Nanofabrication and Lithography Techniques
- Advanced Chemical Sensor Technologies
Pohang University of Science and Technology
2016-2025
Pohang Accelerator Laboratory
2009-2024
Konkuk University
2021-2024
Kyungpook National University
2024
Chonnam National University
2017-2022
Korea Post
2020-2021
Government of the Republic of Korea
2021
Pusan National University
2002-2013
Daejeon Health Institute of Technology
2005-2013
Sookmyung Women's University
2009
A Dirac fermion in a topological semimetal is quadruple-degenerate quasiparticle state with relativistic linear dispersion. Breaking either time-reversal or inversion symmetry turns this system into Weyl that hosts double-degenerate states opposite chiralities. These two kinds of quasiparticles, although described by equation, do not necessarily obey Lorentz invariance, allowing the existence so-called type-II fermions. The recent theoretical discovery fermions evokes prediction...
The structural and electronic properties of HfO2 thin films grown by atomic layer deposition (ALD) under various ozone concentrations were investigated using X-ray diffraction (XRD), photoemission (XPS), reflectometry (XRR), absorption spectroscopy (XAS) their fine structure (XAFS) analysis. It was found that in the as-grown states, oxygen stoichiometry local amorphous domains are maintained nearly as constants even when film is without external supply, while some C–O bonds remain between...
Recently, α-RuCl3 has attracted much attention as a possible material to realize the honeycomb Kitaev model of quantum-spin-liquid state. Although magnetic properties have been extensively studied, its electronic structure, which is strongly related physics, poorly understood. Here, structure was investigated by photoemission (PE) and inverse-photoemission (IPE) spectroscopies. The band gap directly measured from PE IPE spectra found be 1.9 eV, larger than previously estimated values. Local...
Angle-resolved photoemission spectroscopy (ARPES) study of a layered electride Ca2N was carried out to reveal its quasi-two-dimensional electronic structure. The band dispersions and the Fermi-surface map are consistent with density functional theory results except for chemical potential shift that may originate from high reactivity surface excess electrons. Thus, existence anionic electrons in interlayer region is strongly supported by ARPES.
Alzheimer's disease (AD) is an irreversible neurodegenerative characterized by progressive long-term memory loss and cognitive dysfunction. Neuroimaging tests for abnormal amyloid-β (Aβ) deposition are considered the most reliable methods diagnosis of AD; however, cost such testing very high generally not covered national insurance systems. Accordingly, it only recommended individuals exhibiting clinical symptoms AD supported assessments. Recently, was suggested that dysregulated...
We report the first case of successful measurements a localized spin antiferromagnetic transition in delafossite-type PdCrO2 by angle-resolved photoemission spectroscopy (ARPES). This demonstrates how to circumvent shortcomings ARPES for investigation magnetism involved with spins limited size two-dimensional crystals or multi-layer thin films that neutron scattering can hardly study due lack bulk compared surface. Also, our observations give direct evidence ordering pattern Cr3+ ions...
BiFeO3 (BFO) is currently considered to be the most promising candidate material for device applications of room-temperature multiferroics. However, there exist some controversial arguments on origin enhanced magnetization and polarization observed in epitaxially constrained BFO thin film heterostructures. More specifically, issue can addressed by following question: Can epitaxial strain enhance ferroelectric BFO? To clarify this issue, we have systematically examined characteristics...
Abstract It was recently reported that circular dichroism in angle-resolved photoemission spectroscopy (CD-ARPES) can be used to observe the Berry curvature 2H-WSe 2 (Cho et al. Phys Rev Lett 121:186401, 2018). In study, mirror plane of experiment intentionally set perpendicular crystal plane, such becomes a symmetric function about experimental plane. present we performed CD-ARPES on with taken as Within an constraint, two geometries are possible for CD-ARPES. The distributions expected...
The electronic structure of amorphous ZnO film (a-ZnO) was examined by O K- and Zn L3-edge x-ray absorption spectroscopy valence band photoemission spectroscopy. Comparative studies a-ZnO a wurtzite (w-ZnO) revealed decrease in 4s-O 2p hybridization strength the localization 4s as consequence local structural disorder, indicating limited electron hopping interactions a-ZnO. 0.1 eV higher Fermi-level compared to w-ZnO suggests that electrical properties are different from those due even...
We investigated site-specific magnetic behaviors of multiferroic ${\mathrm{Ba}}_{0.5}{\mathrm{Sr}}_{1.5}{\mathrm{Zn}}_{2}({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}{)}_{12}{\mathrm{O}}_{22}$ using Fe ${L}_{2,3}$-edge x-ray circular dichroism. The Al dopants mostly replace the ${\mathrm{Fe}}^{3+}$ ions at octahedral (${O}_{h}$) sites, which contribute unquenched angular momenta through off-centering displacements. This replacement greatly reduces anisotropy energy to change order from...
The layered vanadium antimonides AV3Sb5 (A = K, Rb, Cs) are a recently discovered family of topological kagome metals with rich phenomenology strongly correlated electronic phases including charge order and superconductivity. Understanding how the singularities inherent to structure linked observed many-body is topic great interest relevance. Here, we combine angle-resolved photoemission spectroscopy density functional theory reveal multiple kagome-derived van Hove (vHs) coexisting near...
With a single experimental system, all of the correlated parameters needed to evaluate lithographic performance EUV photoresists can be measured.
Interlayer coupling between individual unit layers is known to be critical in manipulating the layer-dependent properties of two-dimensional (2D) materials. While recent studies have revealed that several 2D materials with significant degrees interlayer interaction (such as black phosphorus) show strongly properties, origin based on electronic structure drawing intensive attention along exploration. Here, direct observation a highly dispersive single band direction puckered PdSe2 an...
Carbon-fluorine bonds in fluorinated molecules can undergo homolytic cleavage reactions when electrons are injected, and the resulting radicals combine to form network structures characterized by reduced solubility. This crosslinking chemistry suggests a new category of patterning materials that function under electron beam (e-beam) extreme ultraviolet (EUV) lithographic conditions. Although this enables production 50 nm or smaller-sized features simple fluoroalkylated polymers, it is...
We have investigated adsorption of pyrazine molecules on the Si(100)-2×1 surface at 300 K by using high-resolution photoemission spectroscopy (HRPES) and near-edge X-ray absorption fine structure (NEXAFS) in partial electron yield mode. The Si 2p, C 1s, N 1s core-level spectra reveal that is directly bonded to silicon dimer rows through two para-nitrogen atoms, forming new Si–N σ-linkages K. π* orbitals C═C bonds carbon K-edge NEXAFS show a good angular dependence providing an average...
We have demonstrated that the evolution of two-dimensional electron gas (2DEG) system at an interface metal and model topological insulator (TI) Bi$_2$Se$_3$ can be controlled by choosing appropriate kind elements applying a low temperature evaporation procedure. In particular, we found only surface states (TSSs) exist Mn/Bi$_2$Se$_3$ interface, which would useful for implementing electric contact with current channels only. The existence TSSs alone was confirmed angle-resolved photoemission...
The interaction between a magnetic impurity, such as cerium (Ce) atom, and surrounding electrons has been one of the core problems in understanding many-body solid its relation to magnetism. Kondo effect, formation new resonant ground state with quenched moment, provides general framework describe presence impurity. In this Letter, combined study angle-resolved photoemission (ARPES) dynamic mean-field theory (DMFT) on Ce-intercalated graphene shows that Ce-induced localized states near Fermi...
There have been few studies on the factors that determine overall appearance of emulsions. Optical properties are quite important in determining perceived quality emulsion-based products. The an emulsion is determined by way it interacts with electromagnetic radiation visible region spectrum, for example, reflection, transmission, adsorption, and scattering. These interactions principally characteristics droplets (size, concentration, refractive index). present study aims at characterizing...
In this study, we report the synthesis of a dendritic polyphenol characterized by high glass transition temperature (Tg), comparable to that poly(4-hydroxystyrene). Although molecule (DP8) was designed have molecular weight as low 1169 g/mol with eight hydroxyl groups, it exhibited Tg ca. 160 °C along stable amorphous nature when prepared from trityl chloride structural motif. The beneficial effect its revealed DP8 converted an acid-labile derivative, DP8-tBOC, tert-butoxycarbonyl (tBOC)...
In transition metal oxides (TMOs), lots of physical phenomena such as metal–insulator transitions (MIT), magnetism, and ferroelectricity are closely related to the amounts oxygen contents. Thus, understanding surface oxidation process in TMOs its effect important for enhancing performances modern electronic electrochemical devices due miniaturization those devices. this regard, MoO2+x (0 ≤ x 1) is an interesting TMO, which shows MIT driven by change content, i.e. metallic MoO2 insulating...