Spectra of Magnetoplasma Excitations in Back-gate Hall Bar Structures

V. M. Muravev, C. Jiang, I. V. Kukushkin, J. H. Smet, V. Umansky, and K. von Klitzing. Phys. Rev. B, 75, 193307 (2007).

The microwave response of a two-dimensional electron system with a nearby in situ grown back gate has been investigated in transport. Several resonant absorption peaks are detected in the magnetoresistance and can be assigned to the excitation of collective magnetoplasma modes. The results are compared with data measured on a similar electron system but without gate. The two-dimensional plasma spectrum is drastically altered by the gate and exhibits a linear dispersion instead of the conventional square-root dependence anticipated from theoretical considerations.