한정훈 교수

We develop a theory of the magnetic field-induced formation of Skyrmion crystal state in chiral magnets in two spatial dimensions, motivated by the recent discovery of the Skyrmionic phase of magnetization in thin film of ${\text{Fe}}_{0.5}{\text{Co}}_{0.5}\text{Si}$ and in the A phase of MnSi. Ginzburg-Landau functional of the chiral magnet rewritten in the ${\text{CP}}^{1}$ representation is shown to be a convenient framework for the analysis of the Skyrmion states. Phase diagram of the model

We study the single-vortex solution of the t-J model within resonating-valence-bond mean-field theory. We find two types of vortex cores, insulating and metallic, depending on the parameters of the model. The pairing order parameter near both cores have d(x(2)-y(2))+ietad(xy) symmetry. For some range of t/J the calculated tunneling spectrum of the metallic vortex core agrees qualitatively with the STM tunneling data for BSCCO.

We work out the dynamics of the compressible edge of the quantum Hall system based on the electrostatic model of Chklovskii et al. We introduce a generalized version of Wen's hydrodynamic quantization of the dynamics of sharp edge and rederive Aleiner and Glazman's earlier result of multiple density modes. Bosonic operators of density excitations are used to construct a fermion operator and the one-particle Green's function. We also analyze the dynamics starting with the second-quantized Hamilto

A recent observation of the thermal Hall effect of magnetic origin in underdoped cuprates calls for critical reexamination of low-energy magnetic dynamics in an undoped antiferromagnetic compound on square lattice, where traditional, renormalized spin-wave theory was believed to work well. Using the Holstein-Primakoff boson formalism, we find that magnon-based theories can lead to finite Berry curvature in the magnon band once the Dzyaloshinskii-Moriya spin interaction is taken into account expl

We investigate the physics of one-dimensional symmetry-protected topological (SPT) phases protected by symmetries whose symmetry generators exhibit spatial modulation. We focus in particular on phases protected by symmetries with linear (i.e., dipolar), quadratic, and exponential modulations. We present a simple recipe for constructing modulated SPT models by generalizing the concept of decorated domain walls to spatially modulated symmetry defects, and develop several tools for characterizing a

We calculate the effective mass of a single quantized vortex in the Bardeen--Cooper--Schrieffer superconductor at finite temperature. Based on effective action approach, we arrive at the effective mass of a vortex as integral of the spectral function $J(\ensuremath{\omega})$ divided by ${\ensuremath{\omega}}^{3}$ over frequency. The spectral function is given in terms of the quantum-mechanical transition elements of the gradient of the Hamiltonian between two Bogoliubov--deGennes (BdG) eigenstat

We study diffusion in systems of classical particles whose dynamics conserves the total center of mass. This conservation law leads to several interesting consequences. In finite systems, it allows for equilibrium distributions that are exponentially localized near system boundaries. It also yields an unusual approach to equilibrium, which in d dimensions exhibits scaling with dynamical exponent z=4+d. Similar phenomena occur for dynamics that conserves higher moments of the density, which we sy

Introduction: We developed and externally validated a fully automated algorithm using deep learning to detect large vessel occlusion (LVO) in computed tomography angiography (CTA). Method: A total of 2,045 patients with acute ischemic stroke who underwent CTA were included in the development of our model. We validated the algorithm using two separate external datasets: one with 64 patients (external 1) and another with 313 patients (external 2), with ischemic stroke. In the context of current cl

We analyze the recently proposed dipolar background field (BF) theory with couplings to charge and dipole currents. The quasiparticles of the theory are either chargelike or dipolelike, and the mutual braiding statistics between chargelike and dipolelike quasiparticles are dipolar, meaning that it depends on the position of the quasiparticle being encircled. The braiding statistics between two dipolelike quasiparticles is that of ordinary anyons. We further prove that the dipolar BF theory is eq

The low survival rate of patients with glioblastoma is in part due to the heterogeneity in the cell population of glioblastoma that includes cancer stem cells (CSCs). CSC niches include a hypoxic core that is also closely linked to self-renewal ability, migration, and drug resistance. Here, we report a CSC culture method in three-dimensional microfluidic cell culture devices under gravity-driven perfusion, which we dub hypoxia chips (H-chips). In H-chips, glioblastoma cells, U87, spontaneously f

We consider the influence of magnetic excitations on the local density of states in the d-wave superconductor. The magnetic susceptibility is calculated within the renormalized $t\ensuremath{-}{t}^{\ensuremath{'}}\ensuremath{-}J$ model while its influence on the quasiparticle self-energy is considered in the framework of a model proposed by Polkovnikov et al. [Phys. Rev. B 65, 220509 (2002)]. We find the local density of states (LDOS) is spatially modulated, with the associated wave vectors both

A phase diagram of two Mott-Hubbard planes interacting with a short-range Coulomb repulsion is presented. Considering the case of equal amount of doping by holes in one layer as electrons in the other, a holon-doublon interlayer exciton formation is shown to be a natural consequence of Coulomb attraction. Quasiparticle spectrum is gapped and incoherent below a critical doping ${\ensuremath{\delta}}_{c}$ due to the formation of excitons. A spin-liquid-insulator (SLI) phase is thus realized withou

A recent demonstration of the periodic oscillation of resistance in the thin film of the ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ superconductor with a hole in the film suggests that charge-$4e$ and charge-$6e$ Cooper pairs may have condensed in this compound. While exciting, such interpretation calls for a precise determination of the effective area for the passage of Cooper pairs from one end of the lead to the other. Unlike the traditional Little-Parks effect where the rim around the hole is thi