Lateral surface magnetoplasma modes of type II semiconductor superlattices

The recently developed theory of superlattice lateral surface magnetoplasmon is extended to type II superlattices consisting of alternating two-dimensional planes of electrons and holes. The magnetoplasmon dispersion relation is calculated by transforming the two coupled integral equations for the a.c. potential into a composite matrix equation. This method can be generalized to study charge density collective excitations in an arbitrary multi-component superlattice.     

Magnetoplasmon replica in the recombination radiation spectra of a quasi-two-dimensional electron gas in GaAs/AlGaAs quantum wells

The radiative recombination spectra of two-dimensional electrons with free photoexcited holes are investigated for a wide variety of GaAs/ AlGaAs quantum wells, with different thicknesses and electron densities. It is found that for certain, close to integral, filling factors an intense line corresponding to an Auger process — radiative recombination with the emission of an additional magnetoplasmon — appears in the luminescence spectrum. The new line is shifted to lower energies with respect to the zero Landau level, and the magnetic field dependence of the energy splitting between these lines agrees with the theoretical concepts of the dispersion of magnetoplasmon excitations. This makes it possible to estimate the magnetoplasmon energy at the roton minimum. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 8, 539–544 (25 October 1997)     

Temperature effects on the magnetoplasmon spectrum of a weakly modulated graphene monolayer

In this work, we determine the effects of temperature on the magnetoplasmon spectrum of an electrically modulated graphene monolayer as well as a two-dimensional electron gas (2DEG). The intra-Landau band magnetoplasmon spectrum within the self-consistent field approach is investigated for both the aforementioned systems. Results obtained not only exhibit Shubnikov-de Haas (SdH) oscillations but also commensurability oscillations (Weiss oscillations). These oscillations are periodic as a function of inverse magnetic field. We find that both the magnetic oscillations, SdH and Weiss, have a greater amplitude and are more robust against temperature in graphene compared to a conventional 2DEG. Furthermore, there is a π phase shift between the magnetoplasmon oscillations in the two systems which can be attributed to Dirac electrons in graphene acquiring a Berry's phase as they traverse a closed path in a magnetic field.     

Submillimeter wave induced resistance oscillations in ultra-high mobility two-dimensional electron systems

Submillimeter wave induced resistance oscillations in two ultra-high mobility GaAs/Al_0.24Ga_0.76As quantum well samples have been investigated by means of a backward wave oscillator and far-infrared laser at ³He temperatures. Subnikov–de Haas oscillation, submillimeter wave induced resistance oscillation, and magnetoplasmon resonance occur simultaneously in this frequency regime. The primary radiation induced resistance minimum shifts toward cyclotron resonance with increasing radiation frequency. The positions of these minima agree well with those of the magnetoplasmon resonance. The higher-order harmonics of the resistance oscillation remain around the multiples of the cyclotron resonance frequency. An in situ transmission measurement exhibits an asymmetric broadening of the cyclotron resonance, appearing as a combination of the cyclotron resonance and the magnetoplasmon resonance, but no features directly linked to the microwave induced resistance oscillation can be seen.     

Absorption of Electromagnetic Waves by Plasma Oscillations in an Infinite Two-Dimensional Electron Gas in a Magnetic Field

JETP Letters - New weakly damping magnetoplasmon modes in an unbounded two-dimensional electron system have recently been predicted. It can be expected that, if the frequency of light at a given...     

Effect of an External Magnetic Field on Magnetoplasmons in Finite Thue-Morse Metal-Metal Superlattices

We have investigated the properties of the magnetoplasmon polariton excitation of a finite Thue-Morse superlattice structure which consists of two building blocks with nonzero plasma frequency. We find that there exist some new modes in an external magnetic field.     

On the observation of surface magnetoplasmons

It is shown that, of the two techniques (grating or prism coupling) proposed for the observation of surface magnetoplasmons, the prism technique appears far superior. An analytic reflectivity formula is presented which will be necessary in the analysis of surface magnetoplasmon experimental data.     

Influence of retardation effects on a 2D magnetoplasmon spectrum

Within a dissipationless limit, the magnetic field dependence of the magnetoplasmon spectrum for an unbounded two-dimensional electron gas (2DEG) system was found to intersect the cyclotron resonance line and, then, approach the frequency given by light dispersion relation. Recent experiments done for macroscopic disc-shaped 2DEG systems confirm theoretical expectations.     

Magnetoplasma oscillations of a two-dimensional electron system with spin-orbit interaction in a lateral superlattice

Low-frequency magnetoplasmon modes in a one-dimensional lateral superlattice with Rashba spin-orbit splitting are considered. Such modes correspond to oscillations related to virtual transitions within a Landau level that become possible due to the broadening of each Landau level into a band produced by the superlattice potential. The specificity of the one-dimensional intersubband plasmons emerging in such a system has been revealed.     

Plateaus in the dispersion of two-dimensional magnetoplasmons in GaAs quantum wells: theoretical evidence of an electron reservoir

The filling-factor-dependent plateau-type dispersion of the long-wavelength magnetoplasmon in high-mobility two-dimensional electron system observed by Holland et al. [Phys. Rev. Lett. 93, 186804 (2004)10.1103/PhysRevLett.93.186804] can be explained by the well-established semiclassical dispersion, by adopting the electron reservoir hypothesis previously proposed in order to explain the integer quantum Hall effects.     

Manifestations of incompressible strips in the edge magnetoplasmon spectrum in the quantum Hall effect regime

The behavior of the main edge magnetoplasmon mode in the quantum Hall effect (QHE) regime has been analyzed by the method of optical detection of resonance microwave absorption. Near a filling factor of 2 at a temperature of about 0.3 K, the main edge mode splits into two modes seemingly due to broadening of the incompressible strip at the edge of the two-dimensional electron gas under such conditions.     

Far-infrared response of quantum-dot molecules

We report an analysis of the dipole response of a symmetric quantum-dot molecule as a function of the dot-dot separation and intensity of a perpendicular magnetic field. The potential barrier is assumed proportional to the interdot distance using a two-center oscillator potential. The results are obtained within the symmetry-unrestricted TDLSDA. It is shown that the FIR details, specially the fragmentation of the low-energy brach, are quite sensitive to the interdot separation and that in both the small and large separation limits the results converge towards the analytic Kohn's magnetoplasmon energies. The validity of the LSDA is checked by comparison with the Hartree-Fock dipole spectrum in one case. Received 29 November 2000     

Damping of the magnetoplasmon propagating along a rough dielectric-semiconductor interface

The damping of a surface magnetoplasmon propagating along a rough dielectric-semiconductor interface is considered. The interaction between charge carriers in the semiconductor and the boundary has been taken into account both in the “specularity parameter” and a microscopic model of the boundary. The effective surface relaxation frequency has been analyzed as a function of the boundary parameters and the magnetic field.     

Exchange effect and magneto-plasmon mode dispersion in an anisotropic two-dimensional electronic system

The exchange effect and the magneto-plasmon mode dispersion are studied theoretically for an anisotropic twodimensional electronic system in the presence of a uniform perpendicular magnetic field.Employing an effective lowenergy model with anisotropic effective masses,which is relevant for a monolayer of phosphorus,the exchange effect due to the electron-electron interaction is treated within the self-consistent Hartree-Fock approximation.The magnetoplasmon mode dispersion is obtained by solving a Bethe-Salpeter equation for the electron density-density correlation function within the ladder diagram approximation.It is found that the exchange effect is reduced in the anisotropic system in comparison with the isotropic one.The magneto-plasmon mode dispersion shows a clear dependence on the direction of the wave vector.     

Cyclotron spin-flip mode in the extreme quantum limit

In a two-dimensional electron system, the combined excitation (the cyclotron spin-flip mode) associated with changes in both orbital and spin quantum numbers is investigated. The energy of the cyclotron spin-flip mode is studied as a function of the electron filling factor. Comparative dependences of the decay times of the cyclotron spin-flip mode and the magnetoplasmon are measured. It is shown that, as the filling factor increases from v = 0 or decreases from v = 1, the damping of the cyclotron spin-flip mode increases significantly, while the magnetoplasma mode remains undamped.     

Magnetoplasmon excitations in quantum dot arrays

Motivated by the far-infrared transmission experiments of Demel et al., we have investigated the magnetoplasmon excitations in an array of quantum dots within the Thomas–Fermi–Dirac–von Weizsäcker (TFDW) approximation. Detailed calculations of the magnetic dispersion and power absorption from a uniform radiation field unambiguously demonstrates that the noncircular symmetry of the individual dots is responsible for the anticrossing behaviour observed in the experiments. The interdot Coulomb interaction is unimportant at the interdot separation of the samples studied.     

Universal relation between hall conductivity and the damping constant of edge magnetoplasma resonances

The spectra of edge magnetoplasma excitations in two-dimensional (2D) electron disks have been analyzed by the method of optical detection of resonant microwave absorption. The magnetic dispersion of an edge magnetoplasmon in samples with a high 2D electron density is found to be poorly reproduced by existing theoretical models. Analysis of the magnetic-field dependence of the linewidth of resonant microwave absorption for samples with various 2D electron densities shows that the inverse width of the main mode of resonant microwave absorption is universally proportional to the Hall resistance of 2D electrons.     

Raman spectroscopy of magnetoplasma excitations in a system of two-dimensional electrons in inclined and parallel magnetic fields

The dispersion of magnetoplasma excitations of two-dimensional electrons in oblique and parallel magnetic fields is investigated by the method of Raman scattering of light. The inclination of the field is used to distinguish the signals due to volume hot luminescence from the signals due to Raman scattering by two-dimensional electrons. The dependence of the magnetoplasmon energy on the inclination angle of the field is measured for different momentum transfers. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 12, 974–978 (25 June 1996)     

Observation of an interedge magnetoplasmon mode in a degenerate two-dimensional electron gas

We study the propagation of edge magnetoplasmons by time-resolved current measurements in a sample which allows for selective detection of edge states in the quantum Hall regime. At filling factors close to nu=3 we observe two decoupled modes of edge excitations, one of which is related to the innermost compressible strip and is identified as an interedge magnetoplasmon mode. From the analysis of the propagation velocities of each mode the internal spatial parameters of the edge structure are derived.     

Effect of an External Magnetic Field on the Plasmon Polaritons of Thue-Morse Semiconductor Superlattices

The collective magnetoplasmon polariton excitations in a semiconductor superlattice with the thicknesses arranged in Thue-Morse sequence are studied. We take the effect of retardation into account and assume the system is subjected to an external static magnetic field applied parallel to the interfaces. It is found that the spectrum of the polariton has the Cantor-like structure, and the total widths of the bands show scaling properties with increasing the generation. The external magnetic field makes the bands become more narrow and shift to higher frequencies for the optical modes and to lower frequencies for the acoustic modes. For a given excitation frequency, the localization properties,of the modes will be changed if we vary the external field.