Measurement of the chemical potential in angle-aligned WS₂/WSe₂ moire superlattice

Recently, TMD moire superlattices have been demonstrated as a highly tunable platform with strong electron correlation. Various 2D quantum phases have been reported in this system, such as Mott insulator, generalized Wigner crystal states and quantum anomalous effect. With the ability to detect sample’s local conductivity, microwave impedance microscopy (MIM) has been used to observe a series of correlated insulating states at both integer and fractional fillings of the moire superlattice. Here, we report measurement of the chemical potential in moire heterobilayer devices (WS₂/WSe₂) with a dual gate geometry. A monolayer graphene is used as the top gate and its carrier density is determined by the potential difference with the moire heterobilayer. With the graphene’s local carrier density and conductivity probed with MIM and fixed by adjusting the gate voltage, the change in the chemical potential of the moire heterobilayer can be detected. We will discuss measurement results of its chemical potential when the moire heterobilayer is tuned through various correlated insulating states.