We have extended earlier measurements of the magnetoresistance in a periodically modulated two-dimensional electron gas to high magnetic fields, where the cyclotron radius, ${\mathit{r}}_{\mathit{c}}$, is much smaller than the period, a, of modulation. A giant nonoscillatory magnetoresistance was found to rise beyond the range of low-field (Weiss) oscillations periodic in 1/B. Its value in a magnetic field of a few tesla may exceed the zero-field resistance value, ${\mathrm{\rho }}_0$, by 1 to 2 orders of magnitude. This result is in agreement with the semiclassical theory by Beenakker, if a modulation of the electron mobility is taken into account.

• Received 16 March 1992

DOI:https://doi.org/10.1103/PhysRevB.46.4324