Absence of back-scattering in twisted bilayer graphene with disorder

The phase diagram of twisted bilayer graphene (TBG) depends profoundly on the twist angle, which is a novel tuning parameter but also a source of disorder. Here we mimic TBG with a tight-binding model of two nanotubes with opposite chiral angles (△θ∼3.5°), the 1D analogue of TBG. We study how the densities of states and electrical conductivity are affected by twist angle disorder. A re-scaling procedure enables the simulation of the magic angle regime (△θ∼1°) [1]. For the calculation of the conductivity through a region with disorder, we develop a decimation technique in the spirit of [2], which yields the pristine electrodes self-energies. Twist disorder damps van-Hove peaks and creates charge localization. However, the conductivity of disordered systems (e.g. 1.02°@1.12°) is free of back-scattering within the flat bands, indicating that in this regime carriers might be impervious to such disorder.

[1] L.A. Gonzalez-Arraga, J.L. Lado, F. Guinea, PRL, 10, 107201 (2017).
[2] T. Cea, N.R. Walet, F. Guinea, Nano letters, 19(12), 8683-8689 (2019).