Study of the phase-shift in the linear-polarization-angle-dependence of the microwave radiation-induced magnetoresistance oscillations in the GaAs/AlGaAs system

Microwave- and terahertz-induced magneto-resistance oscillations (MTIMRO) in the two-dimensional electron system have been a topic of interest since the observation of photo-excited zero-resistance states in the GaAs/AlGaAs system. Some theoretical developments in this area have been based on the premise of linear-polarization-insensitivity of MTIMRO. Recent studies using new experimental methods have shown, however, a strong linear polarization sensitivity of MTIMRO.[1,2] In addition, Ramanayaka \textit{et al.}[2] have observed that the phase shift $\theta_{0}$, which is a parameter in a fitting formula to sinusoidal variation of diagonal resistance, R$_{\mathrm{xx}}$, with polarization angle, $\theta $, as R$_{\mathrm{xx}}(\theta )=$A$\pm $Ccos$^{\mathrm{2}}(\theta $-$\theta_{0})$, depends upon radiation frequency $f$, magnetic field $B$, and sign of $B$.[2] Here, we investigate the dependence of the phase shift $\theta_{0}$ in the linear-polarization-angle-dependence upon the above-mentioned experimental variables. In particular, we examine the relationship between $f$ and $\theta _{0}$. The results will be compared with theory.[3,4] [1] R. G. Mani \textit{et al.}, Phys. Rev. B 84, 085308 (2011). [2] A. N. Ramanayaka \textit{et al.}, Phys. Rev. B 85, 205315 (2012). [3] J. Inarrea, Appl. Phys. Lett. 100, 242103 (2012). [4] X. L. Lei and S. Y. Liu, Phys. Rev. B 86, 205303 (2012). Work has been supported by DOE DE-SC0001762.