Coulomb drag in graphene/hBN/graphene moir\'e heterostructures

We report on the observation of Coulomb drag between graphene-hexagonal boron nitride (hBN) moir\'e heterostructure with a moir\'e wavelength of ~10 nm and an intrinsic graphene with a lattice constant of ~0.25 nm. By tuning carrier densities of each graphene layer independently, we find that the charge carriers in moir\'e mini-bands, i.e., near the satellite Dirac point (sDP), can be coupled with the massless Fermions near the original Dirac point (oDP), strongly enough to generate a finite drag resistance. At high temperature (T) and large density (n), the drag resistances near both oDP and sDP follow a typical n-1.5 and T² power law dependence as expected for the momentum transfer process and it also satisfies the layer reciprocity. In contrast, at low T, the layer reciprocity is broken in both regions that suggest dominant energy drag. Furthermore, quantitatively, the drag resistances near sDPs are smaller than those near oDP and they deviate from T² dependence below ~100 K. These results suggest that the coupling between the carriers in moir\'e mini-bands and those in original Dirac bands may not be of a simple Fermi liquid nature.