  The microwave-photoexcited high mobility GaAs/AlGaAs two-dimensional electron
system exhibits an oscillatory-magnetoresistance with vanishing resistance in
the vicinity of magnetic fields $B = [4/(4j+1)] B_{f}$, where $B_{f} =
2\pi\textit{f}m^{*}/e$, m$^{*}$ is an the effective mass, e is the charge,
\textit{f} is the microwave frequency, and $j$ =1,2,3... Here, we report
transport with well-resolved Landau levels, and some transmission
characteristics.
