Magnetic field effects on the optical response of a film with a rough surface: Voigt geometry

Using the Rayleigh–Fano modal approach we investigate the optical response of a metallic film with a deterministic rough surface taking into account an external magnetic field in the Voigt geometry. For P-polarized light incident onto a deterministic rough surface we calculate the specular and first-order scattered field amplitudes. We also explore the nonreciprocity property and the coupling of the incident light with the surface magnetoplasmons. It is obtained that the magnetic field strength may increase the gap between two minima produced by the splitting of the minima of the zero-field specular reflection. The dispersion relations of the surface magnetoplasmons predict the possible experimental excitation and detection of these modes.     

Theory of damped surface magnetoplasmons in n-type InSb

A theoretical investigation of surface magnetoplasmons in n-type InSb has been carried out with the effect of damping taken into account. Part of the investigation included surface magnetoplasmons interacting with surface optical phonons. The calculated dispersion curves show backbending, in contrast to the situation were damping is neglected. In addition, there are gaps in the dispersion curves for certain frequency ranges.     

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.     

The linear dispersion coefficient of surface magnetoplasmons

The dispersion of surface magnetoplasmons supported on a semiconductor-vacuum interface which is normal to an applied magnetic field is investigated. It is assumed that the surface possesses a depletion layer and that the dispersion is of hydrodynamic origin. Dimensionless numerical results are obtained for the magnetic field dependence of the linear dispersion coefficient with special reference being given to n-type InSb.     

Measurement of the mean free path of edge magnetoplasmons revealed in the spectra of magnetic oscillations of photovoltage in a two-dimensional electron system under microwave radiation

In the spectrum of photovoltage oscillations that are periodic with respect to the magnetic field and appear on Hall structures under microwave irradiation, two frequency components of oscillations are observed and analyzed. The appearance of these two frequencies in photovoltage oscillations is explained by the existence of two trajectories of edge magnetoplasmons and by the effects of the interference of collective excitations on these trajectories. The effects of the temperature, microwave radiation frequency, and magnetic field strength on the mean free path of edge magnetoplasmons are analyzed.     

Magnetoplasmons in gapped graphene in a periodically modulated magnetic field

Motivated by recent experiments on long‐lived magnetoplasmons in the presence of a perpendicular magnetic field, we investigate the dynamical dielectric response function of graphene in contact with a substrate using the random phase approximation. We add a periodically modulated magnetic field within the graphene plane and address both the inter and intra Landau band magnetoplasmons. Verification of the predicted magnetic modulation effects is possible by experiments analogous to those for the zero gap limit.     

A note on the analysis of the dispersion equation for surface magnetoplasmons in the Faraday configuration

The analysis of the dispersion equation for surface magnetoplasmons in the Faraday configuration for the degenerate case of decaying constants being equal is given from the point of view of understanding the non-existence of the “degenerate modes”. This analysis also shows that there exist well defined “degenerate points” on the dispersion curve with electromagnetic fields varying linearly over small distances taken away from the interface.     

Interaction of surface magnetoplasmons and surface optical phonons in polar semiconductors

A theoretical investigation has been carried out of surface polaritons associated with surface magnetoplasmons coupled to surface optical phonons in polar semiconductors. The coupled mode frequencies are calculated for several orientations of the magnetic field relative to the surface and the direction of propagation in the large wave vector (unretarded) limit. Dispersion curves are calculated for the configuration in which the magnetic field is parallel to the surface and is perpendicular to the wave vector. Experimental possibilities for observing the interaction effects are discussed.     

Magneto-optical Kerr effect enhancement at the Wood's anomaly in magnetoplasmonic crystals

Magneto-optical Kerr effect enhancement in longitudinal and transversal configurations is systematically studied in one- and two-dimensional magnetoplasmonic crystals based on the nanostructured nickel films. Spectral dependences of magneto-optical effects demonstrate resonant features with the Fano-type lineshape in the spectral vicinity of the Wood's anomaly associated with excitation of surface magnetoplasmons in Voigt and Faraday configurations, respectively.     

Surface magnetoplasmons in a structure with a two- and three-dimensional plasma

Collective oscillations of a two-component structure consisting of a plasma half-space with a two-dimensional plasma layer at its boundary in the presence of a magnetic field have been studied. Possible variants of the spectra of surface magnetoplasmons have been analyzed for three main mutual orientations of the magnetic field, wavevector, and normal to the surface. The case of the field parallel to the boundary where the frequency is an odd function of the wavevector has been discussed in detail.     

Occurrence of a gap in the spectrum of magnetoplasma excitations of a two-dimensional electron disk subjected to a strong in-plane magnetic field

The effect of a parallel magnetic field on the dispersion of bulk and edge magnetoplasmons in a disk-shaped two-dimensional electron system is investigated. It is found that the anisotropy of the electron effective mass that appears in a parallel magnetic field lifts the degeneracy of plasma oscillations in the disk. This is accompanied by the occurrence of a gap in the spectrum of magnetoplasmons, and the magnetic dispersion of these excitations changes from a linear to a parabolic one. The width of the gap is determined by the difference between the frequencies of plasma oscillations along the field and transverse to the field and grows quadratically with the in-plane field strength.     

Nonhomogeneous electrostatic oscillations in two-dimensional systems

A new type of excitations — electrostatic oscillations (ESO) — are shown to exist in the finite superlattices (SL). The ESO are the limiting case of the surface magnetoplasmons when the scale length of the spatial variations in the fields and currents is comparable with the sample dimensions. The formal similarity is found between the ESO and the magnetization vibrations in ferromagnetic materials (Walker's modes [1,2]). The main feature of the ESO is the independence of their frequencis on the absolute dimensions of a sample.     

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.     

Optic-phonon-magnetoplasmons at the interface of two polar semiconductors

An interface between two polar semiconductors can support a whole new family of seven type of optic-phonon magnetoplasmons. Six of these arise due to nonequivalence property of propagation introduced by the magnetic field in Voigt configuration and one mainly due to finite plasma density ratio at the interface.     

Magnetoplasma spectra of two-dimensional electron rings

A hydrodynamical approach is employed to study the collective excitations of a two-dimensional electron gas confined in a ring geometry, under a normal magnetic held. The theory predicts a rich spectrum of magnetoplasma excitations, with several branches of high- and low-frequency resonances. It is shown that the low-frequency resonances can be identified as edge magnetoplasmons localized at the inner and outer boundaries of the ring, exhibiting their characteristic antidot-like and dot-like features. The high-frequency resonances are essentially bulk two-dimensional magnetoplasmons. Our calculated magnetoplasma modes and their associated induced charge densities and dipole moments are compared with a recent experiment, and it is found that most of the experimentally observed features of the spectrum are accounted for with the present theory.     

On the dispersion relation of magnetoplasmons in a planar graphene-based superlattice

The dispersion relation for magnetoplasmons in a planar superlattice with periodically alternating regions of gapless and gapped modifications of graphene has been derived within the frame of the random-phase approximation. The contribution of virtual transitions between the lower electron miniband and the upper hole miniband to the polarization operator has been taken into account in addition to the contribution of virtual intra-miniband transitions.     

New type of B-periodic magneto-oscillations in a two-dimensional electron system induced by microwave irradiation

We observe a new type of magneto-oscillations in the photovoltage and the longitudinal resistance of a two-dimensional electron system. The oscillations are induced by microwave radiation and are periodic in magnetic field. The period is determined by the microwave frequency, the electron density, and the distance between potential probes. The phenomenon is accounted for by interference of coherently excited edge magnetoplasmons in the contact regions and offers perspectives for developing new tunable microwave and terahertz detection schemes and spectroscopic techniques.     

Chiral optical Tamm states at the boundary of the medium with helical symmetry of the dielectric tensor

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.     

The far-infrared absorption of a periodic 2DEG in the transition regime between weak and strong modulation

We study the optical absorption of arrays of quantum dots and antidots in a perpendicular homogeneous magnetic field. The electronic system is described quantum mechanically using a Hartree approximation for the mutual Coulomb interaction of the electrons. The evolution of the absorption is traced from the homogeneous to the strongly modulated case identifying the ensuing collective modes, the magnetoplasmons, and their correlations with inherent length scales of the system.