Observation of Substrate Induced Multiple Dirac Cones in Graphene/ SiC Heterostructure

The coupling between epitaxial graphene layers and various substrates give rise to many interesting phenomena such as the energy gap at the Dirac node and double Dirac cones. Electronic structure of graphene is modulated by the substrate effects. In this work, we measured the electronic structure of bilayer graphene/SiC heterostructure. Apart from the duplicated Dirac cones arising from the interaction with the interfacial reconstruction, 24 additional Dirac cones are clearly observed by angle-resolved photoemission spectroscopy (ARPES) within the 1^stBrillouin zone of graphene. These 24 Dirac cones are directly generated from the coupling between graphene layers and the supporting SiC lattice, a result consistent with our tight-binding simulations. This work paves the way for understanding the direct electronic coupling between graphene and SiC substrates.