Disorder in Twisted Bilayer Graphene

Understand

We develop a theory for a qualitatively new type of disorder in condensed matter systems arising from local twist-angle fluctuations in two strongly coupled van der Waals monolayers twisted with respect to each other to create a flat band moir\'e superlattice.

• The new paradigm of 'twist angle disorder' arises from the currently ongoing intense research activity in the physics of twisted bilayer graphene.
• In experimental samples of pristine twisted bilayer graphene, which are nominally free of impurities and defects, the main source of disorder is believed to arise from the unavoidable and uncontrollable non-uniformity of the twist angle across the sample.
• To address this new physics of twist-angle disorder, we develop a real-space, microscopic model of twisted bilayer graphene where the angle enters as a free parameter.