Engineering Two-Dimensional Hybrid-Order Topological Insulators via Trilayer Coupling
arXiv:2607.12314 · doi:10.1103/ggh1-tpdk
The paper proposes an interlayer‑engineering scheme in a trilayer quantum anomalous Hall system to create a two‑dimensional hybrid‑order topological insulator that simultaneously hosts chiral edge modes and zero‑dimensional corner states within the same bulk gap.
Abstract
We propose an interlayer-engineering scheme to realize a two-dimensional hybrid-order topological insulator, characterized by the coexistence of first-order and second-order topological phases, in a coupled trilayer Chern system. Starting from three quantum anomalous Hall layers with Chern numbers in the decoupled limit, interlayer tunneling hybridizes their edge states into a single chiral edge mode, while simultaneously opening a gap that supports corner states. Consequently, the system exhibits the coexistence of one-dimensional chiral edge states and zero-dimensional corner states within the same bulk gap, a hallmark of the hybrid-order topology. Furthermore, we map out the topological phase diagram, and show that the hybrid-order phase is robust against mass-type disorder. Our results identify interlayer hybridization as a minimal and broadly applicable strategy for engineering coexisting edge and corner states within a topological platform.