Direct Imaging of the Energy Bands of Magic Angle Twisted Bilayer Graphene with the Quantum Twisting Microscope - Part I

One of the core mysteries of magic-angle twisted bilayer graphene (MATBG) lies in understanding the nature of its interacting energy bands. While MATBG has shown topological phenomena, explained by topological Chern bands in momentum space, its electronic behavior also displayed localized characteristics, hinting at a real-space picture. This dichotomy has led to various theoretical models, including the topological heavy fermion model and the Mott semimetal framework, each attempting to reconcile how these contrasting features emerge within the flat bands of MATBG.

Until now, no tool has been capable of imaging these energy bands at low temperatures and with high enough energy and momentum resolution to resolve these puzzles. Recently, we developed the Quantum Twisting Microscope (QTM), which utilizes momentum-resolved tunneling at a twisting van der Waals interface to directly map the energy bands of quantum materials. Until now, however, our measurements of electronic bands have been at room temperature.

In this talk, I will present the first cryogenic measurements of the MATBG bands. Part I of this talk will focus on imaging the energy bands of graphene and twisted bilayer graphene at low temperatures, demonstrating how the flat bands look close to the magic angle.