Yutaka Akagi

Spin Chirality Ordering and Anomalous Hall Effect in the Ferromagnetic Kondo Lattice Model on a Triangular Lattice

We investigate the ground-state phase diagram for the ferromagnetic Kondo lattice model on a triangular lattice by a variational calculation for various spin orderings up to a four-site unit cell. We find that a noncoplanar four-sublattice ordering with a finite scalar spin chirality emerges at and around 1/4 filling, in addition to the 3/4-filled case which was predicted to be induced by the perfect nesting of the Fermi surface. The 1/4-filling phase is stable in a wider range of parameters than the 3/4-filling one, and includes a large region of gapped insulating state characterized by a Chern number. We also compute the Hall conductivity in the chiral-ordered phases.

Hidden Multiple-Spin Interactions as an Origin of Spin Scalar Chiral Order in Frustrated Kondo Lattice Models

We reveal the significance of kinetic-driven multiple-spin interactions hidden in geometrically frustrated Kondo lattice models. Carefully examining the perturbation in terms of the spin-charge coupling up to the fourth order, we find that a positive biquadratic interaction is critically enhanced and plays a crucial role on stabilizing a spin scalar chiral order near 1/4 filling in a triangular lattice case. This is a generalized Kohn anomaly, appearing only when the second-order perturbation is inefficient because of the degeneracy under frustration. The mechanism is potentially common to frustrated spin-charge coupled systems, leading to emergence of unusual magnetic orders.

Quantum solitons with emergent interactions in a model of cold atoms on the triangular lattice

Cold atoms bring new opportunities to study quantum magnetism, and in particular, to simulate quantum magnets with symmetry greater than

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

\text{SU}(2)

Noncoplanar spin canting in lightly-doped ferromagnetic Kondo lattice model on a triangular lattice

. Here we explore the topological excitations which arise in a model of cold atoms on the triangular lattice with

Ground-state Phase Diagram of the Kondo Lattice Model on Triangular-to-kagome Lattices

\text{SU}(3)

Surface and interface effects on a magnetic Chern insulator

symmetry. Using a combination of homotopy analysis and analytic field theory we identify a family of solitonic wave functions characterized by integer charge

Reconstruction of Chiral Edge States in a Magnetic Chern Insulator

\mathbf{Q}=({Q}_{A},{Q}_{B},{Q}_{C})

Effect of Quantum Spin Fluctuation on Scalar Chiral Ordering in the Kondo Lattice Model on a Triangular Lattice

, with

Machine Learning Disordered Topological Phases by Statistical Recovery of Symmetry

{Q}_{A}+{Q}_{B}+{Q}_{C}=0