Giant growth of quantum oscillations in an inhomogeneous 2D electron system

It is detected experimentally for the first time that the connection of 2D electron systems with different electrochemical potentials results in long-range (>50 mu m) electron density disturbances. When a gated region of a Corbino sample is strongly depleted, the amplitude of the magnetoresistance oscillations caused by high density ungated regions is found to increase in direct proportion to the sample resistance, which is dominated by low-density regions with small conductivity. Experiments on samples with an artificial potential profile (antidots and etched rings) below the gate show that the observed effects are not due to contact effects. (C) 1996 American Institute of Physics.