Radiation-induced magnetoresistance oscillations in two-dimensional electron systems under bichromatic irradiation

Abstract

We analyze the magnetoresistance $R_{xx}$ oscillations in high-mobility two-dimensional electron systems induced by the combined driving of two radiation fields of frequency $ω_1$ and $ω_2$, based on the balance-equation approach to magnetotransport for high-carrier-density systems in Faraday geometry. It is shown that under bichromatic irradiation of $ω_2\sim 1.5 ω_1$, most of the characterstic peak-valley pairs in the curve of $R_{xx}$ versus magnetic field in the case of monochromatic irradiation of either $ω_1$ or $ω_2$ disappear, except the one around $ω_1/ω_c\sim 2$ or $ω_2/ω_c\sim 3$. $R_{xx}$ oscillations show up mainly as new peak-valley structures around other positions related to multiple photon processes of mixing frequencies $ω_1+ω_2$, $ω_2-ω_1$, etc. Many minima of these resistance peak-valley pairs can descend down to negative with enhancing radiation strength, indicating the possible bichromaticzero-resistance states.