Realizing a Topological Charge Pump in a Sliding Moiré Heterostructure

In a Thouless charge pump, a sliding lattice potential pumps a quantized amount of charge across an insulator. We describe an experiment to realize a Thouless charge pump by sliding a moiré superlattice formed at the interface of a graphene-hexagonal boron nitride (hBN) heterostructure. Here, the sliding process is enabled by the low interfacial friction between the van der Waals (vdW) material interfaces. Furthermore, unique to a moiré system, translating one layer by one atomic lattice constant leads to an amplified translation of the moiré by one superlattice constant. In order to achieve the sliding, we have developed a cryogenic nanomanipulation apparatus that can mechanically modify the vdW heterostructure while performing electrical measurements. I will discuss our progress on cryogenic nanomanipulation (sliding) as well as measuring the pumped charge in a graphene-hBN moiré system. I will also discuss other experiments enabled by our technique such as twist dependent studies and scanning gate experiments.