Bernstein modes in a laterally modulated two-dimensional electron gas

Abstract

We report far-infrared transmission measurements performed on a two-dimensional electron gas (2DEG) with a lateral modulation of its concentration induced using a split-gate technique. Under magnetic field, when the photon energy is close to the plasmon energy of the modulated 2DEG, a strong coupling of the plasmon with the cyclotron resonance harmonics (up to n = 5), known as Bernstein modes, is observed. At a fixed wavelength of λ = 229 µm, the behaviour of these modes is studied as a function of magnetic field while the modulation strength is varied 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].

Electrical transport and far-infrared transmission in a quantum wire array

“…We believe that this CR shift has consequences on the magnetic field values at which Bernstein modes are observed in the weak modulation regime. This could explain some of the discrepancies between theory and experiment in the data of Lefebvre et al, 97 as the theoretical model used in Ref. 97 does not take into account such a shift of the CR.…”

“…This could explain some of the discrepancies between theory and experiment in the data of Lefebvre et al, 97 as the theoretical model used in Ref. 97 does not take into account such a shift of the CR. Figure 8 shows a series of magnetoresistance curves measured in the parallel configuration for different gate voltages covering both intermediate and strong modulation regimes.…”

“…͑6͒ are seen when the plasmon frequency at Bϭ0 T and the photon frequency are close to each other. 97 These arise as a result of a strong coupling between the magnetoplasmon mode and har- FIG. 6.…”

Far-infrared transmission study of Bernstein modes in a two-dimensional electron gas with a tunable lateral modulation

“…More details on the sample's structure and fabrication are given elsewhere. 14 The application of a voltage between the gate array and the 2DEG is used to partially deplete the regions underneath the metallic stripes from their electrons, and thereby to induce a spatially periodic modulation of the electron concentration. The sample is specially designed to allow switching from a uniform 2DEG to an array of parallel quantum wires in a continuous way, while giving the possibility of making magnetotransport measurements ͑in directions parallel and perpendicular to the wires͒ as well as FIR optical transmission measurements.…”