Experimental evidence of the topological obstruction in twisted bilayer graphene.

ABSTRACT: The rich physics of magic angle twisted bilayer graphene (TBG) results from the Coulomb interactions of electrons in flat bands of non-trivial topology. While the bands' dispersion is well characterized, accessing their topology remains an experimental challenge. Recent measurements established the local density of states (LDOS) as a topological observable. Here, we use scanning tunnelling microscopy to investigate the LDOS of TBG near a defect. We observe characteristic patterns resulting from the Dirac cones having the same chirality within a moiré valley. At higher energies, we observe the Lifshitz transition associated with the Dirac cones mixing. Our measurements provide a full characterization of TBG's band structure, confirming the main features of the continuum model including the

SUBMITTER: Mesple F 

PROVIDER: S-EPMC12748744 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature