Linear polarization rotation study of the radiation-induced magnetoresistance oscillations

The polarization sensitivity of microwave-radiation-induced magneto-resistance oscillations is investigated by rotating, by an angle \textit{$\theta $}, the polarization of linearly polarized microwaves with respect to the long-axis of GaAs/AlGaAs Hall-bar electron devices. At low microwave power, $P$, experiments show a strong sinusoidal variation in the diagonal resistance $R_{xx}$ vs. \textit{$\theta $} at the oscillatory extrema, indicating linear polarization sensitivity in the microwave radiation-induced magneto-resistance oscillations. Surprisingly, the phase shift \textit{$\theta $}$_{0}$ for maximal oscillatory $R_{xx}$ response under photo-excitation appears dependent upon the radiation-frequency $f$, the extremum in question, and the magnetic field orientation or \textit{sgn}(B).