Disorder-Induced Delocalization in Magic-Angle Twisted Bilayer Graphene

Guerrero, Pedro Alcázar;Nguyen, Viet-Hung;Romeral, Jorge Martínez;Cummings, Aron W.;Roche, Stephan;et.al.
(2025) Physical Review Letters — Vol. 134, n° 12 (2025)

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  • Guerrero, Pedro AlcázarCatalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
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  • Nguyen, Viet-Hungorcid-logoUCLouvain
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  • Romeral, Jorge MartínezCatalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
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  • Cummings, Aron W.orcid-logoCatalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
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  • Charlier, Jean-Christopheorcid-logoUCLouvain
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  • Roche, Stephanorcid-logoCatalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
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Abstract
Flat bands in moiré systems are exciting new playgrounds for the generation and study of exotic manybody physics phenomena in low-dimensional materials. Such physics is attributed to the vanishing kinetic energy and strong spatial localization of the flat-band states. Here, we use numerical simulations to examine the electronic transport properties of such flat bands in magic-angle twisted bilayer graphene in the presence of disorder. We find that while a conventional downscaling of the mean free path with increasing disorder strength occurs at higher energies, in the flat bands the mean free path can actually increase with increasing disorder strength. This phenomenon is also captured by the disorder-dependent quantum metric, which is directly linked to the ground state localization. This disorder-induced delocalization suggests that weak disorder may have a strong impact on the exotic physics of magic-angle bilayer graphene and other related moiré systems.
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Guerrero, P. A., Nguyen, V.-H., Romeral, J. M., Cummings, A. W., Garcia, J.-H., Charlier, J.-C., & Roche, S. (2025). Disorder-Induced Delocalization in Magic-Angle Twisted Bilayer Graphene. Physical Review Letters, 134(12). https://doi.org/10.1103/physrevlett.134.126301 (Original work published 2025)