V. M. Muravev

Millimeter/submillimeter mixing based on the nonlinear plasmon response of two-dimensional electron systems

The nonlinear plasmon response of a two-dimensional electron system with an incorporated defect to monochromatic and bichromatic microwave radiation has been investigated. The operation of an electronic device (mixer) based on the plasmon response with a record operational speed has been demonstrated and analyzed. It has been found that the system response time is no more than τ = 25 ps. It has been shown that the nonlinear response of the system is caused by a new physical mechanism of nonlinearity induced by the presence of an inhomogeneity in the electron system.

Novel relativistic plasma excitations in a gated two-dimensional electron system

A new mode is discovered in microwave response of a two-dimensional electron system (2DES) covered by a conducting top gate in the relativistic regime for which the 2D conductivity σ2D>c/2π. This mode shows a very unusual frequency and amplitude dependence on the magnetic field, conductivity, gate geometry, and separation from the 2DES, and survives for temperatures up to 300 K, allowing for new room-temperature microwave and terahertz applications.

Experimental determination of the mean free path of screened edge magnetoplasmons in a two-dimensional electron gas

Magnetic oscillations of the photovoltage in a two-dimensional electron system with the back gate, exposed to microwave radiation, are studied. The oscillations result from the interference of screened edge magnetoplasmons (EMPs). The mean free path of the EMPs is quantitatively determined by analyzing the dependence of the oscillation amplitude on the electron density. The dependences of the mean free path of the EMPs on the two-dimensional electron density, microwave frequency, electron relaxation time, and the magnetic field are studied. It is found that the dependences agree qualitatively with the known theoretical calculations.

Study of edge magnetoplasma excitations in two-dimensional electron systems with various edge depletion profiles

Resonant microwave absorption by two-dimensional electrons has been measured using coplanar and strip methods. The influence of the edge of a two-dimensional system on the dispersion of edge magnetoplasmons has been studied. It has been found that the edge width can be varied within wide limits (by almost two orders of magnitude) by changing the etching depth of the crystal. It has been shown that the edge of the electron system in the case of etching through the quantum well has a width of about 0.2 μm, whereas the edge in the case of shallow etching (e.g., down to the donor layer) is smooth and can be as wide as 12 μm. The influence of a logarithmic factor, depending on the edge width of the electron system, on edge magnetoplasma excitations dispersion has been studied.

Dispersion of Volume Relativistic Magnetoplasma Excitation in a Gated Two-Dimensional Electron System

The dispersion of the volume relativistic magnetoplasma mode in a gated GaAs/AlGaAs quantum well is measured using a coupled resonators detection technique. The weakly damped relativistic mode exhibits an unusual zigzag-shaped magnetodispersion dependence dictated by the diagonal component of the resistivity tensor ρxx. The plasma excitation easily hybridizes with photon modes due to a large spatial delocalization of its electromagnetic field. The effects of electron density and structure geometry on the excitation spectrum have been investigated.

Observation of acoustic edge magnetoplasmons near the filling factor ν = 1

Investigation of acoustic edge magnetoplasma excitations in micrometer two-dimensional electron disks has been carried out. It has been shown that additional acoustic edge magnetoplasma modes associated with the existence of incompressible strips in the two-dimensional electron system caused by Zeeman spin splitting can appear in the system at temperatures below the Zeeman energy. The magnetic dispersion of the first “spin” branch of acoustic edge magnetoplasmons has been studied. It has been shown that this mode vanishes as the filling factor ν = 1 is approached. The dependence of the relative amplitude of acoustic edge magnetoplasmons on the filling factor has also been investigated.

Plasmonic interferometer for spectroscopy of microwave radiation

We report the observation of photovoltage oscillations in back-gated two-dimensional electron systems when tuning the density under incident microwaves and in the absence of a magnetic field. The oscillations are periodic in the inverse of the square root of the density. They originate from the interference of screened bulk plasmons with a linear dispersion. This phenomenon can be exploited to devise a spectrometer-on-a-chip for millimeter waves. The influence of a perpendicular magnetic field is investigated and reveals a transformation of screened bulk plasmons waves into screened edge magnetoplasmons.

On the response time of plasmonic terahertz detectors

The response time of a plasmonic terahertz detector is investigated using two independent experimental techniques relying on time-resolved and heterodyne measurements, respectively. Both methods demonstrate that the detector response time does not exceed 110 ps. The results obtained suggest that the designed terahertz detector can be used as a component of high-speed telecommunication systems of a new generation.

Coherent and Incoherent Contributions to the Damping of Cyclotron Magnetoplasma Resonance for Two-Dimensional Electrons

The spectrum of resonant microwave absorption for a two-dimensional electron disk is studied by the optical detection technique. The dependence of the width of cyclotron magnetoplasma resonance on the electron density and on the size of the two-dimensional electron system is analyzed. The contributions of the coherent radiative and incoherent collision mechanisms to the relaxation of magnetoplasma excitations are measured. It is demonstrated that the ratio of the length of the electromagnetic wave and the lateral size of the twodimensional electron system is an important parameter determining the width of the resonance.

Edge magnetoplasma excitations in a two-dimensional electron system with strong screening

The dispersion of plasma and magnetoplasma excitations in two-dimensional electron systems with a closely spaced back gate is experimentally investigated using optical detection of microwave absorption. In disk samples, both cyclotron and edge screened magnetoplasmons are observed. It is established that the magneticfield behavior of both modes is in good agreement with the existing theory describing the dispersion of screened magnetoplasma excitations. It is shown that, in a strong magnetic field, the dispersion of screened magnetoplasma excitations is quadratic. This makes it possible to associate magnetoplasma waves with a quasiparticle with a mass, which possesses a number of unique properties.