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Chern-selective multivalley flat bands in twisted mono-bilayer and mono-trilayer
Phys. Rev. B 113, 125116 – Published 9 March, 2026
DOI: https://doi.org/10.1103/rc4z-qw9q
Abstract
The interplay between moiré flat bands originating from different valleys can give rise to a variety of exotic quantum phases. In this work, we investigate the electronic properties of twisted mono-bilayer (A-AB) and mono-trilayer (A-ABA) using first-principles calculations and continuum models. Unlike previous studies on twisted bilayer systems, in which low-energy flat bands originate solely from the valleys, in A-AB and A-ABA twisted () the moiré bands at low energies arise from both the and valleys, with spin Chern numbers (for ) and (for ), respectively. We show that the multivalley moiré flat bands are governed by interlayer hybridization effects, and that different stacking configurations and thicknesses tune the relative energy alignment between the and valley moiré flat bands. By constructing valley-resolved continuum models and performing Wannierization for the low-energy moiré bands, we further uncover that the Berry curvature and quantum metric distributions can be effectively tuned by the layer number and stacking configuration. Unlike other moiré systems, where only one kind of valley influences the low-energy physics, the simultaneous appearance of two distinct types of valleys with different symmetries establishes A-AB and A-ABA as ideal platforms for studying layer-controlled multivalley physics.