28 citations · 84 across the 11 of their papers we have counts for
12 papers
Quasi-periodic flat-band model constructed by molecular-orbital representation
Tomonari Mizoguchi, Yasuhiro Hatsugai
We construct a tight-binding model that hosts both a quasi-periodic nature and marcoscopically-dengenerate zero-energy modes. The model can be regarded as a counterpart of the Aubr…
Topological photonics of generalized and nonlinear eigenvalue equations
Takuma Isobe, Tsuneya Yoshida, Yasuhiro Hatsugai
Topological photonics is developed based on the analogy of Schrödinger equation which is mathematically reduced to a standard eigenvalue equation. Notably, several photonic systems…
Topological pump and its plateau transitions of -leg spin ladder
Kota Yamamoto, Yoshihito Kuno, Tomonari Mizoguchi +2
A topological pump on an leg spin ladder is discussed by introducing spatial clusterization whose adiabatic limit is a set of site staircase clusters. We…
Topological-to-Topological Transition Induced by On-Site Nonlinearity in a One-Dimensional Topological Insulator
Kazuki Sone, Yasuhiro Hatsugai
Recent studies have extended the notion of band topology to nonlinear systems by defining nonlinear counterparts of eigenvalue problems. They have found the nonlinearity-induced to…
Topological domain-wall pump with spontaneous symmetry breaking
Yoshihito Kuno, Yasuhiro Hatsugai
A domain-wall pump by an extended cluster model of spins is proposed with local gauge invariance. Its snapshot ground state is gapped and doubly degenerated due to $…
Evolution of flat bands in two-dimensional fused pentagon network
Tomonari Mizoguchi, Mina Maruyama, Yasuhiro Hatsugai +1
Theoretical quest of flat-band tight-binding models usually relies on lattice structures on which electrons reside. Typical examples of candidate lattice structures include the Lie…
Hidden chiral symmetry for kagome lattice and its analogs
Tomonari Mizoguchi, Yasuhiro Hatsugai
Chiral symmetry plays an essential role in condensed matter physics. In tight-binding models, it is often attributed to bipartite lattice structures, and its typical consequence is…
Band structures of generalized eigenvalue equation and conic section
Takuma Isobe, Tsuneya Yoshida, Yasuhiro Hatsugai
Band structures of several metamaterials are described by generalized eigenvalue equations where complex bands emerge even if the involved matrices are Hermitian. In this paper, we…
Exceptional points and non-Hermitian skin effects under nonlinearity of eigenvalues
Tsuneya Yoshida, Takuma Isobe, Yasuhiro Hatsugai
Band structures of metamaterials described by a nonlinear eigenvalue problem are beyond the existing topological band theory. In this paper, we analyze non-Hermitian topology under…
Bulk-edge correspondence for nonlinear eigenvalue problems
Takuma Isobe, Tsuneya Yoshida, Yasuhiro Hatsugai
Although topological phenomena attract growing interest not only in linear systems but also in nonlinear systems, the bulk-edge correspondence under the nonlinearity of eigenvalues…
Molecular-orbital representation of generic flat-band models
Tomonari Mizoguchi, Yasuhiro Hatsugai
We develop a framework to describe a wide class of flat-band models, with and without a translational symmetry, by using "molecular orbitals" introduced in the prior work (HATSUGAI…
Chiral symmetry and its manifestation in optical responses in graphene: interaction and multi-layers
Y. Hatsugai, T. Morimoto, T. Kawarabayashi +2
Chiral symmetry, fundamental in the physics of graphene, guarantees the existence of topologically stable doubled Dirac cones and anomalous behaviors of the zero-energy Landau leve…