Quantum point contacts fabricated in graphene van der Waals heterostructures using AFM anodic oxidation

Quantum Hall interferometers rely on high-quality quantum point contacts (QPCs) to properly function as a tool to observe exchange statistics of quasiparticles. Graphene van der Waals heterostructures offer the advantage to gate-define QPCs using encapsulating graphite layers allowing for high-quality, tunable edge potential profiles. Recent work on such devices has relied on traditional electron-beam lithography to form the required gate structures, and challenges have emerged in reducing disorder resulting from the etching process. Here we report on using an alternative method, anodic oxidation lithography, which utilizes a voltage-driven Atomic Force Microscope (AFM) tip in a controlled environment to create high-quality incisions in graphite gates. In this talk we focus on optimizing this method for fabricating QPCs and characterize the resulting devices using transport measurements. These results pave the way for the observation of anyonic exchange statistics in future generations of graphene quantum Hall interferometers.