DC TRANSPORT OF COMPOSITE FERMIONS IN WEAK PERIODIC POTENTIALS

dc transport through one-and two-dimensional periodic modulations of d ensity has been investigated near half filling of the lowest Landau le vel. For both geometries, the modulation, which is rather weak for ele ctrons at small magnetic fields, triggers an unexpectedly strong respo nse for composite fermions. The dramatic effect observed in 1D grating s is best described as a large positive magnetoresistance emanating fr om the half filled state. 2D gratings display four peaks similar to di mensional resonances observed in antidot arrays despite the small modu lation amplitude.