Tunable Electronic Structure by In-Situ Ferroelectric Domain Writing in Graphene/BiFeO3 Heterostructures

Integration of functional ferroic domain structures in 2D systems with existing layered electronic architectures represents a major opportunity for advancement of tunable nanoelectronics. Here, we demonstrate nanoscale writable electronic structure of graphene by in-situ ferroelectric domain manipulation in high-quality graphene/BiFeO3 heterostructures. Crystalline BiFeO3 thin films are grown by pulsed laser deposition, and the ferroelectric domain structure and domain wall properties are characterized by piezoresponse force microscopy (PFM). Few- and monolayer graphene flakes are transferred in ultrahigh vacuum by direct bonding for a pristine interface. The ferroelectric polarization domains in BiFeO3 determine the local charge landscape at the heterointerface, which modulates the band structure of the adjacent graphene layer and results in large switchable resistivity. We characterize the effect of the domain polarization on the electronic structure of the graphene layer by STM, with particular focus given to the domain wall region. Additionally, we show that the electronic structure of graphene can be locally patterned by in-situ manipulation of the ferroelectric domains by external field. Finally, we discuss the stability of written domains and suitability for device application.