  Surface acoustic waves (SAWs) on piezoelectric insulators can generate
dynamic periodic potentials inside one-dimensional and two-dimensional
materials. These periodic potentials have been utilized or proposed for various
applications, including acoustoelectric charge pumping. In this study, we
investigate acoustoelectric charge pumping in graphene with very low
electrostatic disorder. By employing a graphite top gate on
boron-nitride-encapsulated graphene, we adjust the graphene carrier
concentration over a broad range, enabling us to examine the acoustoelectric
signal in both mixed-carrier and single-carrier regimes. We discuss the
benefits of hBN-encapsulated graphene for charge pumping applications and
introduce a model that describes the acoustoelectric signal across all carrier
concentrations, including at the charge neutrality point. This quantitative
model will support future SAW-enabled explorations of phenomena in
low-dimensional materials and guide the design of novel SAW sensors.
