Photonic obstructed atomic insulator
Abstract
Topological quantum chemistry (TQC) classifies the topological phases by real-space invariants in which obstructed atomic insulators belong to the trivial case but sometimes show the feature of higher-order topological insulator. Here, for a two-dimensional magnetic photonic obstructed atomic insulator, we show that the emergence of corner states is associated with the Wyckoff positions. In such a square lattice with four + elements and four - elements, corner states appear when the superlattice exposes Wyckoff positions. And the corner states will decrease when the number of exposed Wyckoff positions decreases and disappears when Wyckoff positions no longer stand at the edge. By arranging all the magnetic rods into one magnetization direction, we find that time-reversal symmetry is not important for corner states. Our finding indicates that the real-space distribution of atoms determines the feature of higher-order topological insulators for obstructed atomic insulators in TQC.
Cite
@article{arxiv.2506.23713,
title = {Photonic obstructed atomic insulator},
author = {Hongyu Chen},
journal= {arXiv preprint arXiv:2506.23713},
year = {2025}
}