Visualization and transport properties of complex graphene moiré superlattices

Over the past few years, graphene deposited on hexagonal boron nitride (hBN) has gained a great level of attention thanks to the unique physical properties of such heterostructures. In particular, due to the comparable lattice constants of graphene and hBN, the latter two can be aligned with respect to each, that results in the formation of a superlattice potential, also known as a Moire pattern. Such a potential drastically affects the band structure of graphene enabling the observation of many spectacular phenomena, i.e. second generation of Dirac points, Hofstadter butterflies, Brown-Zak high-temperature oscillations, etc. In this presentation, we will present an approach that allows characterization of graphene-hBN superlattices by atomic force microscopy (AFM). We will show that the AFM operating in the peak-force mode accompanied by the Raman spectroscopy provides a clear visualization of the Moire potential enabling the measurements of its period and strain distribution. Last, we will discuss electronic properties of complex graphene/hBN superlattices formed by a dual-alignment of graphene with respect to two hBN slabs.