Layer-resolved flat-band excitations in magic-angle twisted bilayer phononic graphene
Phys. Rev. B 113, 024306 – Published 12 January, 2026
DOI: https://doi.org/10.1103/yspj-ctmr
Abstract
Although rich phenomena have been microscopically observed in magic-angle twisted bilayer graphene, layer-resolved excitations within the flat bands, which provide a direct understanding of the coupling between the two layers with subtle interlayer interactions, have not been directly observed. Such observations are fundamentally limited in electronic systems due to the lack of minimally invasive probes between the two adjacent graphene layers. Here, with phononic twisted bilayer graphene (PTBG) as an analog to the electronic system, we directly measure the excitations within and in between each adjacent layer, enabling in situ layer-resolved flat-band excitations observations. Paired with theoretical modeling, the layer-resolved measurement directly demonstrates the interlayer coupling effect in magic-angle twisted PTBG, presenting its significance. Meanwhile, in large-angle twisted PTBG, the low-energy states are only mildly affected by the moiré effect and can be approximated by those from two decoupled Dirac cones from the individual phononic layers. This work extends twistronics to artificial crystals, opening new approaches to investigate moiré physics.
