Structure and electronic properties of graphene on ferroelectric LiNbO₃ surface

Highlights: • Interface structure of graphene on O terminated LiNbO₃ surface. • Asymmetry gap around Dirac point. • Berry phase calculations confirm a valley Hall effect. - Abstract: We investigate the structural and electronic properties of graphene on the O terminated LiNbO₃(001) surface by density functional theory simulations. We observe that the first graphene layer is covalent bonded with the surface O atoms and buckles a lot. While considering second layer graphene upon the first layer, it almost recovers the planar structure and the interface interaction breaks the AB sublattice symmetry which leads to a valley Hall effect. Our results reveal the interface structure of graphene-ferroelectric heterostructure and provide the way for valleytronic applications with graphene.