Magic-angle twisted bilayer graphene (MATBG) hosts ultra-flat moiré bands that enable a remarkable landscape of correlated phases, including unconventional superconductivity. Yet every real device carries a degree of unavoidable disorder—charge puddles, strain, substrate inhomogeneity—so a central question remains: how robust are these exotic states once realistic imperfections are accounted for?
To address this head-on, we performed large-scale quantum-transport simulations using a realistic tight-binding model of MATBG, allowing us to track how disorder reshapes transport length scales within and beyond the flatband window. We uncover a striking, counter-intuitive regime: inside the flat bands, the mean free path can increase as disorder is enhanced, revealing a disorder-induced delocalization mechanism that sharply contrasts with the conventional monotonic degradation expected at higher energies. Importantly, this transport anomaly is mirrored by a disorder-dependent quantum metric—a quantum-geometric marker tied to ground-state localization— indicating that even “weak” disorder can significantly renormalize quantumgeometric ingredients that are widely discussed as key to MATBG superconductivity and related correlated phenomena.
For experiments, the message is practical and testable: disorder should not be treated only as a nuisance, but as a parameter with a distinct flat-band fingerprint. Our results offer a quantitative route to rationalize device-to-device variability and motivate targeted protocols—energy/filling-resolved transport mapping while systematically tuning the disorder landscape via dielectric environment, screening, and substrate choice—to capture the predicted nonmonotonic trend and the crossover back to standard localization at stronger disorder.
