Plasmon Excitations in Partially Screened Two-Dimensional Electron Systems (Brief Review)

The latest achievements in the study of the physical properties of plasmon excitations in partially screened two-dimensional electron systems based on AlGaAs/GaAs heterostructures have been reviewed. It has been revealed that a proximity plasmon, i.e., a specific type of two-dimensional plasma waves, is excited in such systems. It has been established experimentally that these plasma waves have a number of new physical properties. First, the dispersion relation of partially screened plasmons combines features of both screened and unscreened two-dimensional plasmons. Second, an edge branch is absent in the magnetic dispersion relation of the revealed proximity mode. Finally, a "charged" relativistic plasma mode with a number of unique properties is excited in the system if the gate is connected to the two-dimensional system through an external circuit. The reported new results expand the horizon of possible applications of plasmonics in the field of microwave and terahertz electronics.