Research

Research Subjects:

    Theory of Condensed Matter and Statistical Physics, Field Theory

Research Topics:

  (main topic) Topological magnetism:

    ・Strongly correlated systems and frustrated magnetism

            - Chiral magnetic ordering (triple-Q state) associated with topological Hall effect in centrosymmetric itinerant magnets (magnetic Chern insulator)

        - Mechanism of chiral magnetic ordering (triple-Q state) in centrosymmetric itinerant magnets (Kondo lattice systems)

            - Effect of quantum spin fluctuation in the Kondo lattice model

            - Spontaneous formation of kagome network and Dirac semimetal on a triangular lattice

        - Magnetic supersolid state in spin-charge coupled systems

            - Dynamics of Magnetization in spin-charge coupled systems

            - Photocontrol of spin scalar chirality in centrosymmetric itinerant magnets

            - CP2 triple-Q state in the SU(3) Kondo lattice model

            - Nonlinear transports in insulating magnets/itinerant magnets

            - High harmonic generation from topological spin textures in centrosymmetric itinerant magnets

    ・Topology in condensed matter

            - CP2 Skyrmion crystals (spin nematic Skyrmion crystals)

            - Magnetic (Magnonic) topological phases and their transport properties

            - Magnonic topological crystalline insulators and their novel electric-field response

            - Novel topological defects (excitations) and BKT transition in quantum spin nematics

        - Dynamics of topological defects (excitations) in quantum spin nematics

            - Disordered topological insulators/superconductors

            - Bosonic topological phases

            - Symmetry-protected topological (SPT) phases in quantum spin systems

            - Topological invariants for (disordered) topological phases

            - Symmetry-protected quantization of complex Berry phases in many-body non-Hermitian systems

            - Electric field induced thermal Hall effect of triplons in quantum dimer magnets

    ・Field theory

            - Solitons (Skyrmions) in the F2 nonlinear σ-model

          - Solitons (Skyrmions) in the CP2 nonlinear σ-model with a Dzyaloshinskii-Moriya type interaction

            - Fractional Solitons (Skyrmions) molecules in a CPN-1 model

            - Gravitational wave analogues in spin nematics and cold atoms

    ・Development and improvement of computational methods

        - Efficient spin flipping for simulation of topological excitations

            - Global update in spin systems by restricted/deep Boltzmann machine (RBM/DBM)

            - Classification of quantum phases by supervised/unsupervised machine learning

            - Molecular dynamics simulations in quantum spin nematics

Methods: 

    Field theory, Modern mathematics, Numerical methods such as Mean-field theory, Variational method, 

    Exact diagonalization, Monte Carlo simulation, Simulated annealing, Variational Monte Carlo method (VMC),

    Molecular dynamics simulations, and Machine learning