Microwave photo-excited transport in the GaAs/AlGaAs 2DES*

Collective bulk plasmon excitations of a two dimensional electronic system (2DES) evolve into magnetoplasmons in the presence of a perpendicular magnetic field, with a low frequency cutoff determined by the dispersion relation ω_MP = (ω_C² + ω_P²)^1/2, where the plasmon frequency ω_P² = (ne² /2ε_effε_om*)k, with k the plasmon wave vector, and ω_c the cyclotron resonance frequency. Studies of narrow Hall bar type GaAs/AlGaAs specimens of width, w, have long ago suggested that localization of the plasmon within the boundaries of the sample can lead to the wave vector selection k = π/w and the observation of the corresponding resonance in magnetotransport under photoexcitation. The observation of zero-resistance states and associated radiation induced magnetoresistance oscillations under microwave/mm-wave/terahertz photoexcitation has brought new interest in the role of the magnetoplasmon, if any, in the ultra high mobility GaAs/AlGaAs 2DES and its interaction with this photo-excited transport phenomena mentioned above. In this study, we re-examine through experiment the role of the magnetoplasmon in the GaAs/AlGaAs magnetotransport and report the results.