Moiré-engineered kagome bilayers hosting quantized corner states

Abstract

Twisted bilayer kagome (TBK) lattices provide a tunable moiré platform for realizing higher-order topological (HOT) phases in two dimensions. In this study, we employ tight-binding modelling together with Wilson-loop and nested Wilson-loop analyses to investigate the topological properties of the TBK system. The calculated band structure exhibits a finite bulk gap, within which the Wilson spectra reveal a quantized quadrupole moment Q_xy = 1/3, corresponding to fractional corner charges Q^∞_c ≈ −0.31e. Finite-size scaling confirms the thermodynamic stability of these fractionalized charges, while local density of states (LDOS) spectra and real-space maps visualize sharply localized zero-energy corner modes. Under an applied magnetic flux, the corner states exhibit a continuous spectral flow across the bulk gap, demonstrating higher-order topological pumping. These results establish twisted kagome bilayers as a controllable moiré platform for realizing higher-order topology and suggest experimentally accessible signatures for detecting quantized corner states in kagome-based van der Waals heterostructures.