Work

Magic angle (in)stability and mobility edges in disordered Chern insulators

Year: 2025

Type: article

Abstract: Why do experiments only observe one magic angle in twisted bilayer graphene, despite standard models like the chiral limit of the Bistritzer–MacDonald (BM) Hamiltonian predicting an infinite number? In this article, we explore the relative stability of larger magic angles compared to smaller ones. Specifically, we analyze how disorder impacts these angles as described by the BM Hamiltonian in the chiral limit. Changing focus, we investigate the topological and transport properties of a specific magic angle under disorder. We identify a mobility edge near the flat band energy for small disorder, showing that this mobility edge persists even when all Chern numbers are zero. This persistence is attributed to the system’s C 2 z T symmetry, which enables non-trivial sublattice transport. Notably, this effect remains robust beyond the chiral limit and near perfect magic angles, aligning with experimental observations.

Source: Journal of Physics A Mathematical and Theoretical

DOI: 10.1088/1751-8121/adfbb2

Authors: Simon Becker, Izak Oltman, Martin Vogel

Institutions: ETH Zurich, University of California, Berkeley, Centre National de la Recherche Scientifique, Institut de Recherche Mathématique Avancée

Language: English

Topic: Topological Materials and Phenomena

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,325

Funder: Agence Nationale de la Recherche