Near-field magnetooptics in resonant light scattering by a linear nanoprobe

A theory of the magnetooptical scattering of light by a near-field linear probe parallel to the surface of a magnet is presented. The probe is modeled by a cylindrical nanowire supporting long-lived surface plasmons. The scattering of light is considered in the longitudinal magnetooptical Kerr effect geometry (with magnetization parallel to the sample surface and the plane of light incidence). The resonant interaction of the probe + image system is taken into account in the self-consistent approximation of the multiple scattering theory, while the magnetooptical interaction is described in the linear approximation with respect to magnetization. Polarization characteristics of the scattered light and the magnetooptical modulation of light intensity, which are resonantly enhanced by the surface plasmons, have been studied.     

Plasmon-Excitonic Polaritons in Metal-Semiconductor Nanostructures with Quantum Wells

A theory of plasmon-exciton coupling and its spectroscopy is developed for metal-semiconductor nanostructures. Considered as a model is a periodic superlattice with cells consisting of a quantum well and a layer of metal nanoparticles. The problem is solved self-consistently using the electrodynamic Green’s functions taking account of resonant polarization. Coulomb plasmon-exciton interaction is associated with the dipole surface plasmons of particles and their image charges due to excitonic polarization of neighboring quantum well. Optical reflection spectra are numerically investigated for superlattices with GaAs/AlGaAs quantum wells and silver nanoparticles. Superradiant regime caused by one-dimensional Bragg diffraction is studied for plasmonic, excitonic and plasmon-excitonic polaritons depending on the number of supercells. The plasmon-excitonic Rabi splitting is shown to occur in reflectivity spectra of resonant Bragg structures.     

Optical Spectroscopy of Schottky Nanostructures Au/GaAs: Plasmon Resonances and Anisotropy

Semiconductors - The Schottky nanostructures Au/GaAs with Au nanoclusters are prepared by annealing of thin gold films deposited on nitridized GaAs(001) surface. The nanostructures are diagnosed...     

Excitons and polaritons in AlGaAs semiconductor alloys

For Al_xGa_1?x As semiconductor alloys with x = 0.15 and 0.21 at temperatures T = 1.7?380 K, the band-edge absorption spectra are measured and the temperature dependence of the integrated absorption coefficient is obtained. The results are analyzed in the context of two mechanisms of the exciton-polariton energy transfer that can lead to the variation of the integrated absorption in systems with random excitonic potential at low temperatures. In one case, the temperature anomaly in the absorption results from the competition between the excitonic and electromagnetic mechanisms of the energy transfer in a quasi-homogeneous medium (a virtual crystal) with spatial dispersion. In the other case, the effect is related to the reemission of light by resonance localized excitons along finite chains of quantum wells in the absence of excitonic transfer. The observation of a characteristic temperature dependence of the integrated absorption supports the existence of exciton polaritons in the samples under study. It is found that integrated absorption in Al_0.15Ga_0.85As alloy saturates above the critical temperature T _c = 155 K. It is demonstrated that, in the temperature range from 1.7 to 60 K, the inhomogeneous broadening due to the fluctuating potential is responsible for the dominant contribution to the width of the excition line in the alloys investigated and considerably exceeds the homogeneous broadening caused by the interaction of excitons with phonons and charged impurities.     

On the Theory of Plasmon–Excitons: An Estimate of the Coupling Constant and the Optical Spectrum

Semiconductors - The structure of the optical spectra related to the resonant interaction of quasi-two-dimensional excitons and localized plasmons is investigated theoretically. The constant of...     

On the theory of near-field magneto-optical microscopy via plasmonic modes of nanowire

The results of a theory of near-field magneto-optical microscopy with a linear probe scanning the near-surface region of a sample are presented. A cylindrical nanowire supporting surface plasmons is considered as a model of the probe. The polar magneto-optical Kerr effect is studied in scattering of light by near-surface nanowire and magnetic nanodomain. The problem is solved self-consistently in the dipolar interactions of the nanowire with the sample surface and in magnetization-linear approximation of magneto-optics. The near-field magneto-optical response depending on the distance between probe and domain is obtained, and the microscopy resolving power is estimated.     

Raman spectra of iron-modified amorphous carbon

Raman spectra of amorphous carbon films containing encapsulated iron (a-C:Fe) have been measured in the frequency range 200–1000 cm⁻¹. The concentration of encapsulated iron atoms (3, 26, 38, and 54 at. %) was controlled by changing the relative areas of iron and graphite targets during the film deposition by RF magnetron sputtering and checked by Rutherford backscattering. The Raman spectra of a-C:Fe films display a series of almost equidistant bands spaced by approximately 110 cm⁻¹. This character of the spectrum is explained in terms of the atomic vibrations in short carbon nanotubes formed during the introduction of iron into an amorphous carbon matrix.