Transmission Measurements in a Low Density Two --Dimensional Electron Gas in an Array of Antidots

Under high magnetic fields, the microwave conductivity of a two-dimensional electron system containing an antidot array with factional Landau filling was discovered [1]. On the other hand, at low temperature T$=$0.3 K, we have measured the transmission in the low density (n$=$0.6x10$^{\mathrm{11}}$ cm$^{\mathrm{-2}})$ , ultraclean GaAs/AlGaAs sample with an array of anitidots. In our measurements, we observed an interesting feature around the $\nu =$1, 2, which may be related to the charged edge mode in the integer quantum Hall regime. [1] P. D. Ye, L. W. Engel, D. C. Tsui, J. A. Simmons, J. R. Wendt, G. A. Vawter, and J. L. Reno, Phys. Rev. B, 65, 121305 (2002).