Surface electromagnetic waves on magnetic media

We assume complex magnetic and dielectric properties of two adjacent, isotropic, semi-infinite media and examine surface electromagnetic waves (SEW) at their plane interface. The dispersion curves and non-radiative conditions are derived and compared with other results. Comments are made about which materials will allow surface electromagnetic waves. The importances of the dielectric constants of the sample and the overlayer materials are emphasized with an example, Si and NiO.     

Surface waves in cholesterics in a magnetic field

Propagating waves on the free surface of a cholesteric liquid crystal in a vertical magnetic field are considered for the case when the anisotropy of the magnetic susceptibility is negative. Surface fluctuations distort the helical structure and the dispersion relation and penetration depth are shown to depend on three possible restoring forces: the surface tension, the twist elastic forces associated with the helix, and the magnetic field.     

Attenuation of electromagnetic waves in a semiconductor superlattice in a magnetic field

Magnetoplasma waves and inhomogeneous (complex) waves in an infinite semiconductor superlattice in a magnetic field are studied, and dispersion curves are obtained. It is shown analytically and numerically that, in periodic structures, among inhomogeneous waves, there are many complex waves for which the imaginary part of the wave vector is greater than the real part. The effect of dissipation in a medium on the dispersion curves of magnetoplasma waves is examined. The dependence of the minimum phase velocity on the collision frequency and the magnetic field strength is studied.     

Surface waves in ferrofluids under vertical magnetic field

We present here new experimental results about the waves at the horizontal free surface of a magnetic fluid submitted to a normal magnetic field. The waves are generated by a small modulation at frequency of the vertical field . Using a shadowgraph method, we are able to measure the wavevector k of the 2D waves for a given value of and . The dispersion relation of the surface waves is established experimentally. On the other hand, we propose a theoretical derivation of the dispersion equation which includes a more complete treatment of the magnetic term than the previous works. Finally, we conclude that a linear and inviscid analysis is sufficient to fit well the experimental data, except in the vicinity of the critical field where a surface instability occurs. Received 11 May 1998     

Interaction of space-charge waves in an electron beam with electromagnetic waves in a longitudinal magnetic field

The effect of space charge on the interaction between an electron beam and an electromagnetic wave in a longitudinal magnetic field has been considered. The equations describing the interaction processes have been formulated within the two-dimensional linear theory and solved using the dispersion-equation approach and the successive approximation method.     

Surface electromagnetic waves in a Fermi liquid

Surface electromagnetic waves propagating along a Fermi liquid-dielectric interface are investigated. A dispersion relation for the surface waves is obtained, and the frequency range of their existence is determined. The possibility of determining the contribution of a Fermi liquid to the dielectric permittivity of a metal from experiments on excitation of surface electromagnetic waves is shown.     

Focusing of electromagnetic waves into a biaxial crystal, experimental results

We present experimental results for focusing of an electromagnetic wave from air into a biaxial crystal. These results are compared with numerical results, and good agreement is found. The experimental results show distinct tangential and sagittal foci, whose positions agree with numerical predictions. The theory is outlined both for the exact solution, which includes extra-paraxial geometries and double refraction, and for the paraxial solution, in which double refraction is ignored. We also present a simple ray-optical interpretation of the results, which allows us to predict the positions of the sagittal and tangential foci.     

Surface electromagnetic waves in superconductors

Varying electromagnetic fields at the surface of a superconductor are studied by means of the boson method. It is found that the frequency of the surface electromagnetic waves satisfies a dispersion relation which is entirely controlled by the system itself.     

Surface electromagnetic waves in chromium

The absorption of surface electromagnetic waves in Cr has been measured from 4K up to temperatures just above the Neel temperature T_N = 312K at a frequency large enough to excite electrons across the antiferromagnetic energy gap. The effect of the opening up of the gap immediately below T_N may clearly be seen.     

The phenomenon of conical refraction in a thin-layer periodic semiconductor-dielectric structure in a magnetic field

The propagation of electromagnetic waves along the optical axes of a thin-layer periodic semiconductor-dielectric structure in an external magnetic field (i.e., under conditions of external and internal conical refraction) has been investigated. It is shown that the conditions for conical refraction can be implemented in certain regions by changing the external magnetic field, wave frequency, and thickness of the layers forming the structure. By varying the above-mentioned characteristics, one can efficiently control the conical refraction parameters; in particular, the opening angles of the cone of internal and external conical refraction and the inclination of the optical axes with respect to the periodicity axis can be varied in a wide range. The results of this study may be useful for designing millimeter-wave, submillimeter-wave, and IR devices.     

Evolution of polarization of electromagnetic waves in a plasma with uniformly sheared magnetic field

Summary An analytic solution is found for the evolution of the state of polarization of an electromagnetic wave propagating in a plasma with uniformly sheared magnetic field. It is the generalization of the one found previously for the special case of propagation perpendicular to the magnetic field.     

Surface electromagnetic waves at a superconductor-dielectric interface

This paper reports on the results of investigating the frequency dependence, the structure, and the polarization-and energy-related characteristics of surface electromagnetic waves propagating along a superconductor-dielectric interface. An expression for the complex permittivity of a superconductor is derived in the approximation of a two-component plasma containing “normal” and “superconducting” electrons. Basic relations are obtained in the general case at temperatures T≤T _c (where T _c is the critical temperature) and in the limiting case at T?T _c, when the contribution from normal electrons to the permittivity of the superconductor can be disregarded.     

Dispersion of electromagnetic waves in the presence of magnetic monopoles of electron mass in a uniform magnetic field

The dispersion relation of electromagnetic waves in the presence of magnetic monopoles of electron mass in a uniform magnetic field is obtained. The waves of the frequencyω in the range ω_ϱi<Ω_i<ω<Ω _e <ω_ϱa are analysed. It is shown that the monopole charges lead to observable effects. Finally, the results are applied to a typical pulsar.     

Surface electromagnetic waves in Faraday media

The effect of unidirectional propagation of surface electromagnetic waves on the interface between an isotropic Faraday medium and isotropic optically inactive medium is predicted. Such waves can be excited when the intensity of an external magnetic field exceeds a certain threshold. Solutions to the dispersion relation are analyzed, and existence conditions for the surface waves are established.     

Eigen electromagnetic waves of a coaxial waveguiding structure filled by a non‐uniform dissipative plasma with azimuthal magnetic field

This paper studies the propagation and spatial attenuation of high‐frequency eigen‐symmetric and dipolar electromagnetic waves along a coaxial plasma–metal waveguiding structure that contains a slightly axial and strong radial non‐uniform cylindrical plasma slab in an external azimuthal non‐uniform magnetic field. The influence of such parameters as the effective electron collision frequency, the direct current value producing the external azimuthal magnetic field, parameters that characterize plasma density radial profile, and waveguide geometric parameters on the dispersion, spatial attenuation, and radial field structure of the waves is considered. The regions of waveguiding structure parameters where the electromagnetic wave properties can be effectively controlled are studied and analyzed.