The objectives of this Project are (i) for two-dimensional electron systems (2DES), to study low-lying collective excitations with energies corresponding to the frequency range of 10-170 GHz, (ii) for double-layer systems, to investigate spectrum of internal transitions between ground and excited states of indirect excitons and to measure dispersion of the hybrid collective excitations, (iii) to study mechanisms of coupling between 2D-electrons and microwave irradiation and to elaborate novel sensitive high-frequency selective detectors, (iv) to study mechanisms of photoresponse on microwave radiation in electrical characteristics of high-quality 2DES and mesoscopic systems, produced from 2DES. To reach these objectives, the novel technique, which includes combined microwave- and surface acoustic wave- excitations of 2DES and optical detection of the system response, will be used in combination with traditional electrical methods. The mesoscopic rings and ensembles of the rings will be produced by well-developed methods of the electron beam lithography and reactive etching. Dispersion laws will be determined for spin waves, magnetoplasmons, "cyclotron-like" excitations in the system of composite fermions, and for collective gap-excitations in fractional quantum Hall effect states by resonant microwave- and SAW-absorption spectroscopy. Electronic structure of excitations in coupled double-layer electron-electron and electron-hole systems will be investigated by the methods of resonant microwave absorption and by inelastic light scattering technique. Recently discovered giant magnetoresistance oscillations and the zero-resistance states will be studied both experimentally and theoretically to clarify origin of these phenomena. Effect of microwave radiation on the coherent charge transport and the electro-motive force in a single mesoscopic ring and in an ensemble of mesoscopic rings will be investigated both experimentally and theoretically. In particular, (i) coherent photovoltaic effect will be studied in an ensemble of mesoscopic rings, (ii) circular photovoltaic effect in an asymmetrical ballistic ring exposed to the circular polarized microwave radiation will be searched for, (iii) effect of quantum pumping in an Aharonov-Bohm ring will be studied, (iv) the Berry phase in the microwave induced electromotive force will be searched for in mesoscopic rings containing electron systems with strong spin-orbit interaction. For a system of composite fermions, the Aharonov-Bohm interference effect will be investigated in mesoscopic-ring samples and studied under conditions of the microwave radiation.
38042 Grenoble Cedex 2