2017/11/25 by Yichen Xu, Xu, Yichen, Ruolan Xue +3
Physics and Astronomy · #FOS: Physical sciences #Quantum and electron transport phenomena #Quantum many-body systems #Strongly Correlated Electrons (cond-mat.str-el) #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.1711.09202
openalex publication_date 2017/11/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The higher-order topological insulator (HOTI) protected by spacial symmetry has been studied in-depth on models with square lattice. Our work, based on an alternative model on the breathing Kagome lattice, revealed that the different types of corners in the lattice could actually be conditionally gapless, or always gapped. Using the Wilson loop formalism, we argue that these corner states occur when the eigenvalues of the Wannier Hamiltonian cross through a certain reference point during the conceptual "pumping" procedure. The results demonstrate the corner of the Kagome lattice based HOTI is a zero-dimensional analogue of the 1D chiral edge states on the boundary of a Chern insulator, but with a sensitive dependence on the shape of the corner. Our method of the pumping cylinder, which reveals the symmetry/gapless-ability correspondence, can be generalized into a general scheme in determining the classification of corner(hinge) states in HOTI.