Обобщенная нуль-эллипсометрия в схеме "поляризатор-образец-анализатор"

The null-method in generalized ellipsometry with the use of the compensator-free “polarizer ‒ sample ‒ analyzer” scheme is considered for the case of s- and p-polarized incident light on an anisotropic system. Analytical expressions are given that connect the measured angular value — the analyzer azimuth at the detected radiation intensity minimum — with the (2x2) anisotropic Jones matrix elements. To determine the optical and geometric parameters of the studied anisotropic systems, it is proposed to use this value’s dependence on the sample orientation (azimuth). The method sensitivity is estimated. It was found that it is comparable to the sensitivity of the “polarizer‒compensator‒sample‒analyzer” scheme. A comparative analysis of this method and the known photometric method of generalized ellipsometry in the “polarizer-sample-analyzer” scheme based on measuring the dependence of the reflected light intensity on the sample azimuth at the fixed polarizer and analyzer positions is carried out. It is estimated that, to obtain the same sensitivity of these two methods, the one arc minute error in the proposed method corresponds to the 0.05% relative error in determining the energy reflection coefficient in the photometric method.

Конденсация (псевдо)магнонов в двумерной анизотропной S=1 (псевдо)спиновой системе

—A 2D anisotropic system of S = 1 centers of the charge triplet type in systems with variable valence or “semi-hard-core” boson systems with a limitation for the occupation of lattice sites n = 0, 1, 2 is studied in the framework of the pseudospin formalism. Assuming that the ground state is a quantum paramagnet, the pseudo-spin wave spectrum and also the conditions of the condensation of pseudomagnons with a phase transition to a superconducting state have been found using the Schwinger boson method.

Exciton binding energies in GaAs films on AlxGa1−xAs substrates

We use the fractional–dimensional approach (FDA) to study exciton binding energies in GaAs films on [Formula: see text] substrates. In this approach, the Schrödinger equation for a given anisotropic system is solved in a noninteger-dimensional space where the interactions are assumed to occur in an isotropic effective environment. The heavy-hole and light-hole exciton binding energies are calculated as functions of the film thickness and substrate thickness. The numerical results show that both the heavy-hole and light-hole exciton binding energies decrease monotonously as the film thickness increases. When the film thickness and the substrate thickness is relatively small, the change of substrate thickness has comparatively remarkable influence on both heavy-hole and light-hole exciton binding energies. As the substrate thickness increases, both the heavy-hole and light-hole exciton binding energies increase gradually. When the film thickness or the substrate thickness is relatively large, the change of substrate thickness has no significant influence on both heavy-hole and light-hole exciton binding energies.