Microwave photoresistance in a two-dimensional electron system with anisotropic mobility

The effect of microwave radiation on magnetotransport in single GaAs quantum wells with anisotropic mobility, whose maximum corresponds to the $[1bar 10]$ direction and minimum to the [110] direction, is investigated using the Van der Pauw method. In samples shaped as squares with sides oriented along the $[1bar 10]$ and [110] directions, giant oscillations of magnetoresistance arise under the effect of a microwave field for the both $[1bar 10]$ and [110] orientations of the measuring current I _ac. In the anisotropic two-dimensional system under study, the relative amplitude of microwave photoresistance oscillations in a magnetic field weakly depends on the orientation of I _ac. At a temperature of 4.2 K and a microwave frequency of 130 GHz, magnetic field intervals characterized by close-to-zero resistance manifest themselves only for the case of the [110] orientation of I _ac. The aforementioned experimental results are qualitatively explained by a quasi-one-dimensional potential modulation of the two-dimensional electron gas in the [110] direction.