# Impurity scattering induced carrier transport in twisted bilayer graphene

## TL;DR

This paper theoretically investigates how impurity scattering affects electrical resistivity in twisted bilayer graphene at low twist angles, revealing significant effects of disorder, temperature, and van Hove singularities on transport properties.

## Contribution

It provides a detailed theoretical analysis of impurity-induced resistivity considering both Coulomb and defect scattering, highlighting the violation of Matthissen's rule in twisted bilayer graphene.

## Key findings

- Resistivity increases as twist angle decreases.
- Resistivity is higher at elevated temperatures and near van Hove singularities.
- Matthissen's rule is strongly violated in the system.

## Abstract

We theoretically calculate the impurity-scattering induced resistivity of twisted bilayer graphene at low twist angles where the graphene Fermi velocity is strongly suppressed. We consider, as a function of carrier density, twist angle, and temperature, both long-ranged Coulomb scattering and short-ranged defect scattering within a Boltzmann theory relaxation time approach. For experimentally relevant disorder, impurity scattering contributes a resistivity comparable to (much larger than) the phonon scattering contribution at high (low) temperatures. Decreasing twist angle leads to larger resistivity, and in general, the resistivity increases (decreases) with increasing temperature (carrier density). Inclusion of the van Hove singularity in the theory leads to a strong increase in the resistivity at higher densities, where the chemical potential is close to a van Hove singularity, leading to an apparent density-dependent plateau type structure in the resistivity, which has been observed in recent transport experiments. We also show that the Matthissen's rule is strongly violated in twisted bilayer graphene at low twist angles.