Radiation-intensity and temperature dependence of microwave-induced magnetoresistance oscillations in high-mobility two-dimensional electron systems

We present a detailed theoretical investigation on the radiation induced giant magnetoresistance oscillations recently discovered in high-mobility two-dimensional electron gas. Electron interactions with impurities, transverse and longitudinal acoustic phonons in GaAs-based heterosystems are considered simultaneously. Multiphoton-assisted impurity scatterings are shown to be the primary origin of the resistance oscillation. Based on the balance-equation theory developed for magnetotransport in Faraday geometry, we are able not only to reproduce the observed period, phase and the negative resistivity of the main oscillations, but also to predict the secondary peak/valley structures relating to two-photon and three-photon processes. The dependence of the magnetoresistance oscillation on microwave intensity, the role of dc bias current and the effect of elevated electron temperature are discussed. Furthermore, we propose that the temperature-dependence of the resistance oscillation stems from the growth of the Landau level broadening due to the enhancement of acoustic phonon scattering with increasing lattice temperature. The calculated temperature-variation of the oscillation agrees well with experimental observations.