Characterization of Certain T-ideals from the view point of representation theory of the Symmetric Groups

2010 Mathematics Subject Classification: 08B20, 16R10, 16R40, 20C30.Let K[X] be a free associative algebra (without identity) over a field K of characteristic 0 with free generators X = (X1, X2, ...), and let Pn be the set of all multilinear elements of degree n in K[X]. Then Pn is a KSn-module, where KSn is the group algebra of the symmetric group Sn. An ideal of K[X] stable under all endomorphisms of K[X] is called a T-ideal. If L is an arbitrary T-ideal of K[X] then Ln := Pn ∩ L is a KSn-module too. An important task in the theory of varieties of algebras is to reveal general regularities in the behavior of the sequence A n for various T-ideals A. In certain cases, given a property P, say, of the sequence, one can find a T-ideal L(P) such that a T-ideal L′ satisfies P if and only if L′ contains L(P). The results of this paper have to be regarded from this point of view

Spectral dependence of photoinduced spin precession in DyFeO3

Spin precession was nonthermally induced by an ultrashort laser pulse in orthoferrite DyFeO3 with a pump-probe technique. Both circularly and linearly polarized pulses led to spin precessions; these phenomena are interpreted as the inverse Faraday effect and the inverse Cotton-Mouton effect, respectively. For both cases, the same mode of spin precession was excited; the precession frequencies and polarization were the same, but the phases of oscillations were different. We have shown theoretically and experimentally that the analysis of phases can distinguish between these two mechanisms. We have demonstrated experimentally that in the visible region, the inverse Faraday effect was dominant, whereas the inverse Cotton-Mouton effect became relatively prominent in the near-infrared region.Comment: 27 pages, 8 figure

Optical Properties of Cu(In, Ga)(S, Se)2 Films for Solar Cells

In this paper, we present structural and optical properties of single-phase Cu(In, Ga)(S, Se)2 alloys, which have been prepared using a novel selenization/sulfurization growth process to react copper-indium-gallium alloy films. The grown scheme differs critically from standard two-step grown processes and was carried out without toxic H2S and H2Se gases. The calculated band gap values for layers with varying sulfur content (i.e. S/(S+Se) = 0.16 and 0.19), determined from optical transmission and reflectance measurements, were found to be 1.17 and 1.23 eV respectively. The low temperature PL measurements also confirmed the shift in the band gap of the CIGSS absorber films with sulfur incorporation. In summary, this reaction process produced single-phase CIGSS thin films with controlled sulfur amount suitable for photovoltaic application

Cadmium-free Thin-Film Cu(In,Ga)Se2(In2S3) Heterophotoelements Fabrication and Properties

The method of heat treatment of metallic Cu–In–Ga layers in the N2 inert atmosphere in the presence of selenium and sulfur vapors was used to grow homogeneous films of Cu(In,Ga)(S,Se)2 alloys onto which the CdS or In2S3 films were deposited and, on the basis of these structures, the thin-film glass/Mo/p-Cu(In,Ga)(S,Se)2/n-(In2S3,CdS)/n-ZnO/Ni–Al photoelements were fabricated. The mechanisms of charge transport and the processes of photosensitivity in the obtained structures subjected to irradiation with natural and linearly polarized light are discussed. The broadband hotosensitivity of thin-film heterophotoelements and the induced photopleochroism were detected; these findings indicate that there is an interference-related blooming of the structures obtained. It is concluded that it is possible to use ecologically safe cadmium-free thin-film heterostructures as high-efficiency photoconverters of solar radiation