BERNSTEIN MODES IN A LATERALLY MODULATED 2-DIMENSIONAL ELECTRON-GAS

We report far-infrared transmission measurements performed on a two-di mensional electron gas (2DEG) with a lateral modulation of its concent ration induced using a split-gate technique. Under magnetic field, whe n the photon energy is close to the plasmon energy of the modulated 2D EG, a strong coupling of the plasmon with the cyclotron resonance harm onics (up to n = 5), known as Bernstein modes, is observed. At a fixed wavelength of lambda = 229 mu m, the behaviour of these modes is stud ied as a function of magnetic field while the modulation strength is v aried in the quasi-two-dimensional regime by changing the gate voltage . Experimental data are compared with a classical theory based on the Boltzmann kinetic equation [A V Chaplik and D Heitmann 1985 J. Phys. C : Solid State Phys. 18 3357].