Observations of New Dirac Points in One-Dimensionally-Rippled Graphene on Hexagonal BN Using Scanning Tunneling Spectroscopy

Abstract

Theories predicted that one-dimensional superlattice potentials in graphene would induce new Dirac points, instead of gap opening, due to lattice-induced chirality of charge carriers, but experimental evidence is rarely available in the literature. Here, we report observations of new Dirac points in one-dimensionally rippled graphene on hexagonal boron nitride (h-BN) using scanning tunneling microscopy and spectroscopy. The rippled graphene, formed due to thermal procedures, showed two new Dirac points above and below the Fermi level. The energy difference between a new Dirac point and the Fermi level was proportional to 1/L, where L was the period of a ripple, in agreement with theoretical predictions. Our study shows that the one-dimensional periodic potential is an accessible component for controlling the electronic properties of graphene.