The waveguiding in thin planar structures with quadratic magneto-optical medium is analysed. The permittivity tensor elements with quadratic magneto-optical constants are specified. From synchronous condition for guided modes in layered system with magnetic ordering the dispersion relation of waveguide is presented. The reflection coefficients for s-polarized light at transversal, longitudinal, and polar configurations as incidence angle function are described. The influence of quadratic magneto-optical effect on the resonant character of the waveguiding term is described in detail. The theory covers the situation in which the optical response of the structure is linear in the amplitude of the incident wave.
Magnetoreflectance from GaAs:Mn was measured in the free exciton range for B ≤ 5 T and T = 2.0 K. Combining optical results with magnetization data the value for the exchange parameter N_{0}α-N_{0}β =-(2.3 ± 0.6) eV was obtained. Assuming that N_{0}α ≈ +0.2 eV, the ferromagnetic p-d exchange interaction was found with the magnitude N_{0}β ≈ +2.5 eV.
Recent developments in physics of large gap II-VI Diluted Magnetic Semiconductors (DMS) studied by means of magnetooptical methods are reviewed. Applicability of the Heisenberg Hamiltonian to describe the ion-carrier interaction in new DMS materials is discussed. The paper includes anisotropy related phenomena, new type of bound magnetic polarons found in Van Vleck paramagnetic (Cd,Fe)Se and discusses application of magnetic field to study kinetics of Raman cascades in DMS.
We consider a new magneto-optic effect based upon spin-orbit interaction of the conducting electrons in ferromagnetic metal with the electric field of plane polarized light wave. We calculated off-diagonal components of conductivity tensor for this mechanism of a.c. conductivity. These components determine the current induced by the light wave in the direction perpendicular to the plane of the light polarization. Numerical evaluation shows that the conductivity for this new effect exceeds the off-diagonal components of conductivity tensor for ordinary magneto-optic effect. The components appear to be still considerably smaller than the diagonal elements of the conductivity tensor.
Magnetoreflectance of free exciton and magnetization in Zn_{1-x}Mn_{x}Se (0.0007 < x < 0.12) were measured. The evaluated proportionality factor between the exciton splitting and the magnetization showed a strong concentration dependence. This effect cannot be explained within the mean field approximation and the virtual crystal approximation and it was described within the model including chemical and magnetic disorder.
We present an optical investigation of novel heterostructures based on beryllium chalcogenides with a type-I and type-II band alignment. In the type-II quantum well structures (ZnSe/BeTe) we observed a strong exciton transition involving an electron confined in the conduction band well and a hole localized in the valence band barrier (both in ZnSe layer). This transition is drastically broadened by the temperature increase due to enhanced exciton-acoustic phonon interaction.
Strong optical polarization anisotropy observed previously in the exciton photoluminescence from [100]-oriented quantum wells subjected to the in-plane magnetic field is described within microscopic approach. Developed theory involves two sources of optical polarization anisotropy. The first of them is due to correlation between ψ-functions phases of electron and heavy hole which arise owing to electron Zeeman spin splitting and joint manifestation of low-symmetrical and Zeeman interactions of heavy holes in an in-plane magnetic field. Other optical polarization anisotropy source stems from the admixture of light-holes states to heavy-holes ones by low-symmetry interactions. The heavy hole splitting caused by these interactions separately and the effects of their interference are analyzed. The domination of C_{2v} low-symmetry interaction connected with quantum wells interfaces and/or in-plane deformations takes place in relatively low magnetic field. The directions of this perturbation determine main directions of the π-periodical optical polarization anisotropy. The cubic anisotropy of valence band can add the π/2-periodical contribution to the optical polarization anisotropy. In the case of quantum wells with semimagnetic barriers the Zeeman term contribution can reach value, which dominates the C_{2v} ones, and crossover to polarization connected with magnetic field direction may be observed in low temperature.
Faraday rotation in Hg_{1-x}Mn_{x}Te (x = 0.11) has been investigated experimentally over the temperature range from T = 8 K to 250 K using a Q-switched CO_{2} laser. Due to the exchange interaction between mobile carriers and localized Mn ions, dramatic enhancement of Verdet coefficient at low temperatures has been observed. The values of Verdet coefficient V = 5585 rad T^{-1} m^{-1} at 8 K and V = 1745 rad T^{-1} m^{-1} at 80 K have been obtained for Hg_{0.89}Mn_{0.11}Te at 10.6 μm. The dependence of Faraday rotation on intensity of laser radiation has been observed. Intensity dependent Faraday rotation shows saturation for high laser power. Intensity induced rotation is qualitatively attributed to the dispersion associated with saturable absorption of laser radiation. The results obtained in this work indicate that Hg_{1-x}Mn_{x}Te is a suitable material for Faraday rotator at CO_{2} laser wavelengths for high power laser beam.
The low-temperature far-infrared reflectivity spectra of HgSe and HgSeS are measured and analysed. The results suggest the one-mode behavior of phonon excitations in HgSeS mixed crystals.
Reflectivity and Faraday rotation measurements were carried out on Cd_{1-x}Mn_{x}Te bulk crystals in the complete zinc-blende range of composition 0 < x ≤ 0.71. From a comparison of the results of these two experiments for samples with x ≤ 0.3, we demonstrate that the Faraday angle Θ, measured in limited spectral range, is proportional to the energy splitting of exciton states ΔE, measured at the same temperature (2 K) and magnetic field B (up to 5 T). The determined proportionality constant was used to calculate ΔE values also for x > 0.3. This allowed us to find an empirical description of ΔE values for the whole range of compositions as a function of B and x.
Reflectance and degree of polarization of reflectance of the free exciton in Zn_{1-x}Fe_{x}Te (x ≈ 0.002) was measured at T = 1.9 K and magnetic field up to 5 T. Combining the exciton splitting with the magnetization data we estimated the exchange constant N_{0}(α-β) = 2.1 eV.
We studied the spectral properties of the matrices describing multiple scattering of electromagnetic waves from randomly distributed point-like magneto-optically active scatterers under an external magnetic field B. We showed that the complex eigenvalues of these matrices exhibit some universal properties such as the self-averaging behavior of their real parts, as in the case of scatterers without magneto-optical activity. However, the presence of magneto-optically active scatterers is responsible for a striking particularity in the spectra of these matrices: the splitting of the values of the imaginary part of their eigenvalues. This splitting is proportional to the strength of the magnetic field and can be interpreted as a consequence of the Zeeman splitting of the energy levels of a single scatterer.
The magnetic and magneto-optical properties of the typical representatives of three rare-earth iron garnets (RIG) groups: with heavy rare-earth elements Yb, Er, Dy, Tb; with elements from the middle of lanthanide series Gd, Sm, and with light rare-earth element Nd are presented. In contradistinction to other work on the Faraday rotation, which were done only at 1152 nm (8696 cm^{-1}), here we present FR spectra obtained in the energy region 5500-20000 cm^{-1} with high optical resolution. The investigations have been done at temperatures of 5, 82, 130, 295 K using magnetic field up to 25 kOe applied parallel to the [111] crystallographic axis of the crystals. It has been shown that the contribution proportional to the magnetic field and independent of temperature to the mixing of the ground state multiplets exceeds the paramagnetic contribution in YbIG, ErIG, GdIG, SmIG. In Tb and Dy iron garnets contributions from the two mechanisms have opposite signs, and the paramagnetic mechanism gives the greatest contribution to the Faraday rotation. Nevertheless, the contribution of the diamagnetic mechanism, caused by the influence of the exchange field in the iron sublattices on rare-earth ions, is significant, and it is necessary to take it into account. Anomalously large magneto-optical activity is observed in NdYIG. This is the result of contributions of the same sign and approximately equal in magnitude from the paramagnetic and diamagnetic mechanisms.
We analyse the magneto-photoluminescence of triply negatively charged excitons coupled to a continuum of states. The excitonic complex is confined to a Stranski-Krastanow InAs/GaAs quantum dot embedded in a Schottky diode. Different orientations of the magnetic field have been investigated. A modelling of the Coulomb blockade together with the calculation of the electron Fock-Darwin spectrum has allowed us to predict the magnetic fields of anticrossing between the quantum dot energy states and the wetting layer Landau levels. Good agreement between the theoretical model and the experimental results has been obtained.
In the present work we have shown the efficiency of complex investigation of the ion implanted garnet surface region by magneto-optical and optical methods. We have investigated the optical and magneto-optical properties of the ion-implanted (YBiCaSm)₃(FeGeSi)₅O₁₂ garnet films. It has shown that ion implantation influences significantly the magneto-optical properties of the garnet films and practically does not change its optical characteristics. We have also determined the spectral dependences of the component of the tensor of dielectric permittivity for the surface of ion implanted (YBiCaSm)₃(FeGeSi)₅O₁₂ ferrite-garnet films before and after implantation process. These calculations let us evaluate the influence of implantation on an electronic energy structure of the surface layer for the sample.
We report on the results of first measurements of the Faraday rotation of modulated n-doped multiple quantum wells of GaAs/Al_{x}Ga_{1-x}As (x = 0.312). The measurements have been performed in the magnetic fields up to 13 T at the temperature of 2 K, in the spectral region of interband transitions. A rich structure of magneto-excitons has been found in the measured spectra. Faraday rotation (phase) measurements are proposed as an alternative method to photoluminescence excitation for investigations of magneto-excitons in quantum wells. The dependence of the measured Faraday rotation on magnetic field and hypothetical connections with quantum Hall effect are also discussed.
We demonstrated coherent control of spin precession motion due to the ferromagnetic resonance induced by magnetic field component of ultrashort terahertz pulses. The amplitude of the precession can be controlled by the pulse separation time of the double pulse excitation technique. We succeeded in observing the energy transfer between spin and photon systems, and the energy of the spin system is returned to the second terahertz pulses instantaneously when the precession amplitude is cancelled.
The density of states for ballistic electrons in the presence of an electric field of almost arbitrary shape is calculated for one, two, and three dimensions using the semiclassical quantization in a finite sample. The semiclassical results are compared with these of the complete quantum treatment for a constant electric field. The case of crossed electric and magnetic fields is also considered and it is demonstrated that in this configuration the density of states exhibits a transition between magnetic and electric types of motion. Implications of this transition for the quantum Hall effect are mentioned.
In the photoluminescence excitation spectra of two-dimensional valence holes with large spin gap and strong disorder we find evidence for quantum Hall ferromagnetism and small skyrmions around the Landau level filling factorν=1. This interpretation is supported by numerical calculations.
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