Alexander Hamilton

We build artificial crystal by modulating the electrostatic potential imposed on a two-dimensional electron gas in a GaAs quantum well. In contrast to Moire systems we can fabricate any lattice structure, and independently vary both the amplitude of the potential modulation and the chemical potential. Transport measurements show evolution of the artificial bandstructure from free electrons to those of electrons in artificial graphene and then to flat bands within the same device. The low field Hall effect shows multiple transitions from electron-like to hole-like behaviour as the chemical potential is swept through the different artificial bands, consistent with the transition through Dirac points and van-Hove singularities. The long lattice constant (80-120nm) allows access to high magnetic fields with multiple flux quanta per unit cell (equivalent to thousands of Tesla in natural graphene), and for strong electrostatic modulation we can tune the system from graphene-like bands to Kagome-like bands.