Extremely flat band in bilayer graphene on silicon carbide

Frequent reports of superconductivity in graphite at elevated temperatures even above 300 K demand an explanation. It has been suggested that this is an effect of flat band formation at graphite surfaces and/or interfaces. In the present work we discover by angle-resolved photoemission that bilayer graphene on SiC shows an extremely flat band. We demonstrate that the band extends two-dimensionally around the K point and present a general model for flat band formation in bilayer graphene and related systems.