Beating pattern in radiation-induced oscillatory magnetoresistance in 2DES: coupling of plasmon-like and acoustic phonon modes

We present a microscopic theory on the observation of a beating pattern in the radiation-induced magnetoresistance oscillations at very low magnetic field. We con- sider that such a beating pattern develops as a result of the coupling between two oscillatory components: the first is a system of electron Landau states being harmon- ically driven by radiation. The second is a lattice oscillation, i.e., an acoustic phonon mode. We analyze the dependence of the beating pattern on temperature, radiation frequency and power. We conclude that the beating pattern is an evidence of the radiation-driven nature of the irradiated Landau states that makes them behave as a collective plasma oscillation at the radiation frequency. Thus, the frequency of such plasmons could be tuned from microwave to terahertz in the same nanodevice with an apparent technological application.
Comment: 5 pages, 5 figures