A5067574474- Topological Materials and Phenomena
- Graphene research and applications
- 2D Materials and Applications
- Phase-change materials and chalcogenides
- Quantum and electron transport phenomena
- Advanced Condensed Matter Physics
- Perovskite Materials and Applications
- Quantum many-body systems
- Electronic and Structural Properties of Oxides
- Quantum Dots Synthesis And Properties
- Solid-state spectroscopy and crystallography
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Chalcogenide Semiconductor Thin Films
- Machine Learning in Materials Science
- Advanced Memory and Neural Computing
- Photorefractive and Nonlinear Optics
- Heusler alloys: electronic and magnetic properties
- Nuclear Physics and Applications
- Silk-based biomaterials and applications
- Electrocatalysts for Energy Conversion
- Neuroscience and Neural Engineering
- Magnetic properties of thin films
- Nonlinear Optical Materials Studies
- Magnetic Field Sensors Techniques
Incheon National University
2019-2025
University of Missouri
2022-2023
City University of Hong Kong
2022
University of Seoul
2020
University of California, Irvine
2015-2019
Ulsan National Institute of Science and Technology
2018-2019
Pohang University of Science and Technology
2010-2015
We demonstrate clear weak anti-localization (WAL) effect arising from induced Rashba spin-orbit coupling (SOC) in WS2-covered single-layer and bilayer graphene devices.Contrary to the uncovered region of a shared flake, WAL occurs over wide range carrier densities on both electron hole sides.At high densities, we estimate SOC relaxation rate be ∼ 0.2ps -1 show that it can tuned by transverse electric fields.In addition SOC, also predict existence a'valley-Zeeman' first-principles...
Topological surface states of Bi 2 Se 3 are magnetized by the two-dimensional ferromagnetic van der Waals CrI monolayer.
Magnetic anisotropy often plays a central role in various static and dynamic properties of magnetic materials. In particular, for two-dimensional (2D) van der Waals materials, as inferred from the Mermin-Wagner theorem, it is an essential prerequisite stabilizing ferromagnetic order. this work, we carry out first-principles calculations CrI3 monolayer investigate how its interrelated to adjustable parameters governing underlying electronic structure. We explore routes controlled manipulation...
Proximity effects induced in the two-dimensional Dirac material graphene potentially open access to novel and intriguing physical phenomena. Thus far, coupling between ferromagnetic insulators has been experimentally established. However, only very little is known about graphene's interaction with antiferromagnetic insulators. Here, we report a low-temperature study of electronic properties high quality van der Waals heterostructures composed single layer proximitized α-RuCl3. The latter...
Abstract In symmetry-broken crystalline solids, pole structures of Berry curvature (BC) can emerge, and they have been utilized as a versatile tool for controlling transport properties. For example, the monopole component BC is induced by time-reversal symmetry breaking, dipole arises from lack inversion symmetry, leading to anomalous Hall nonlinear effects, respectively. Based on first-principles calculations, we show that ferroelectricity in tin telluride monolayer produces unique...
Abstract The intrinsic light–matter characteristics of transition-metal dichalcogenides have not only been great scientific interest but also provided novel opportunities for the development advanced optoelectronic devices. Among family dichalcogenide structures, one-dimensional nanotube is particularly attractive because it produces a spontaneous photocurrent that prohibited in its higher-dimensional counterparts. Here, we show WS 2 nanotubes exhibit giant shift current near infrared...
Abstract Various electrophysiological and imaging techniques have been studied for the diagnosis treatment of epilepsy. In particular, electrocorticography (ECoG) provides valuable information that can guide clinical patients with Currently, it is necessary to define benefits ECoG in free-moving animals Here, we present results simultaneous recordings multiple cortical sites responsive neurostimulations epilepsy carried out rats. this study, developed a high-density, flexible electrode array...
We report a discovery, through first-principles calculations, that crystalline Ge-Sb-Te (GST) phase-change materials exhibit the topological insulating property. Our calculations show become insulator or develop conducting surfacelike interface states depending on layer stacking sequence. It is shown originate from ${\text{Sb}}_{2}{\text{Te}}_{3}$ layers in GSTs and can be crucial to electronic property of compounds. These are found quite resilient atomic disorders but sensitive uniaxial...
A recent experiment indicated that a ferromagnetic EuS film in contact with topological insulator ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ might show largely enhanced Curie temperature and perpendicular magnetic anisotropy [F. Katmis et al., Nature (London) 533, 513 (2016).]. Through systematic density functional calculations, we demonstrate addition to the factor has strong spin orbit coupling, surface states are crucial make these unusual behaviors robust as they hybridize extend rather far...
Spin–orbit coupling (SOC) in graphene can be greatly enhanced by proximity it to transition metal dichalcogenides (TMDs) such as WSe2. We find that the strength of acquired SOC depends on stacking order heterostructures when using hexagonal boron nitride (h-BN) capping layer, i.e., SiO2/graphene/WSe2/h-BN exhibiting stronger than SiO2/WSe2/graphene/h-BN. utilize photoluminescence (PL) an indicator characterize interaction between and monolayer WSe2 grown chemical vapor deposition. observe...
Abstract Hybrid halide perovskite solar cells have recently attracted substantial attention, mainly because of their high power conversion efficiency. Among diverse variants, (CH 3 NH )PbI and HC(NH 2 ) PbI are particularly promising candidates bandgap well matches the energy range visible light. Here, we demonstrate that large nonlinear photocurrent in β -(CH α -HC(NH is mostly determined by intrinsic electronic band properties near Fermi level, rooted inorganic backbone, whereas...
The thickness, temperature, and composition studies of spin diffusion length (SDL) Hall angle (SHA) are performed by measuring the magnetoresistance in ${\mathrm{Pd}}_{1\ensuremath{-}x}{\mathrm{Pt}}_{x}/{\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ (=YIG) heterostructures. SDL is found to be invariant changes electron momentum relaxation time varying normal metal (NM) or alloy composition, while SHA exhibits a nonmonotonic dependence on temperature. These findings suggest appearance...
We predict a new class of 3D topological insulators (TIs) in which the spin-orbit coupling (SOC) can more effectively generate band gap. Band gap conventional TI is mainly limited by two factors, strength SOC and, from electronic structure perspective, when absent. While former an atomic property, latter be minimized generic rock-salt lattice model stable crossing bands at Fermi level along with character inversion occurs absence SOC. Thus large-gap TIs or composed lighter elements expected....
Materials can be classified by the topological character of their electronic structure and, in this perspective, global attributes immune to local deformations have been discussed terms Berry curvature and Chern numbers. Except for instructional simple models, linear response theories ubiquitously employed calculations properties real materials. Here we propose a completely different versatile approach get characteristics materials calculating physical observables from real-time evolving...
We investigate magnetic ordering and the quantum anomalous Hall effect (QAHE) in Cr-doped topological insulators using systematic first-principles calculations, explaining mechanism responsible for ferromagnetic order reason why $\mathrm{S}{\mathrm{b}}_{2}\mathrm{T}{\mathrm{e}}_{3}$ is a better QAHE host than $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ or $\mathrm{B}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{3}$. conclude that these have relatively long-range exchange interactions...
Realizing axion insulator state with a uniform magnetization considerably facilitates experimental explorations of the intriguing topological magnetoelectric effect, hallmark three-dimensional (3D) insulators (TIs). Through density functional theory calculations and four-band model studies, we find that magnetic ions Cr3+ in monolayer CrI3 Mn2+ septuple-layer MnBi2Se4 have opposite exchange couplings to surface states 3D TI Bi2Se3. As an exciting result such couplings, is realized by...
Chiral materials have garnered significant attention in the field of condensed matter physics. Nevertheless, magnetic moment induced by chiral spatial motion electrons helical materials, such as elemental Te and Se, remains inadequately understood. In this work, we investigate development quantum angular momentum enforced chirality using static time-dependent density functional theory calculations for an Se chain. Our findings reveal emergence unconventional orbital texture driven geometry,...
Material with a nontrivial topology in its electronic structure enforces the existence of helical Dirac fermionic surface states. We discover emergent topological phases stacked structures insulator and band layers where fermions interact each other particular helicity ordering. Using first-principles calculations model Lagrangian, we explicitly demonstrate that such ordering occurs real materials ternary chalcogen compounds determines their topological-insulating phase. Our results reveal...
We study the effect of Fe impurities in $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ on magnetic phase and topological insulating property using first-principles calculations. In particular, we investigate ferromagnetic-antiferromagnetic transition energy gap variation surface states Fe-doped $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$. find that has a ferromagnetic at dilute doping regime by interplay band inversion intrinsic doping. For higher concentration,...
Emergent physical properties often arise at interfaces of complex oxide heterostructures due to the interplay between various degrees freedom, especially those with polar discontinuities. It is desirable explore if these structures may generate pure and controllable spin currents, which are needed attain unmatched performance energy efficiency in next-generation spintronic devices. Here we report emergence a spin-polarized two-dimensional electron gas (SP-2DEG) interface two insulators,...