INSULATOR-TO-QUANTUM-HALL-LIQUID TRANSITION IN AN ANTIDOT LATTICE

Measurements are reported of the Hall resistance ${\mathrm{\ensuremath{\rho}}}_{\mathrm{xy}}$ and magnetoresistance ${\mathrm{\ensuremath{\rho}}}_{\mathrm{xx}}$ of a two-dimensional electron gas containing a triangular lattice of approximately circular depleted regions (antidots). The transition from insulator to quantum Hall liquid shows a fixed point where the longitudinal resistance is independent of temperature; scaling exponents are determined. ${\mathrm{\ensuremath{\rho}}}_{\mathrm{xx}}$ and ${\mathrm{\ensuremath{\rho}}}_{\mathrm{xy}}$ oscillate with magnetic flux through the unit cell of the antidot lattice, although the dissipation results from hopping between localized states.