Electron heating and polarization-dependence of magnetoresistance in microwave-irradiated two-dimensional electron systems

We examine the electromagnetic absorption, the electron heating and the polarization-dependence of resistivity in a magnetic-field biased high-mobility GaAs-based two-dimensional system irradiated by linearly-polarized microwaves of modest strength. The absorption rate and the rise of the electron temperature are found to be independent of the polarization direction of the radiation and to appear mainly in the regime of radiation-induced magnetoresistance oscillations with the main peak around 20K at the cyclotron resonance ω_c/ω = 1, where ω_c is the cyclotron frequency and ω is the microwave angular frequency. At higher magnetic fields, especially in the range of 2 <; ω_c/ω <; 3, the increase in the electron temperature is almost negligible. The amplitutes of the microwave-induced magnetoresistance oscillations, however, vary sensitively with changing the polarization direction of the microwave at fixed incident radiation power.