On a Result of R. Turner

We study the similarity of perturbed compact operators to operators of block-diagonal structure with respect to some family of orthogonal projection operators, which allows us to refine and essentially strengthen results due to R. Turner. We obtain information about the operator realizing the similarity transformation, present estimates for the eigenvalues and eigenvectors of the perturbed operator, and also study the inverse problem of spectral analysis.     

Properties of InGaAs/GaAs quantum wells with a δ〈Mn〉-doped layer in GaAs

A method of formation of two-dimensional structures containing a δ〈Mn〉-doped layer in GaAs and an In_xGa_1?x As quantum well (QW) separated by a GaAs spacer of thickness d = 4–6 nm is developed using laser evaporation of a metallic target during MOS hydride epitaxy. It is shown that, up to room temperature, these structures have ferromagnetic properties most likely caused by MnAs clusters. At low temperatures (T _m ～ 30 K), the anomalous Hall effect is revealed to occur. This effect is related to hole scattering by Mn ions in GaAs and to the magnetic exchange between these ions and QW holes, which determines the spin polarization of the holes. The behavior of the negative magnetoresistance of these structures at low temperatures indicates the key role of quantum interference effects.     

GaAsSb/GaAs quantum well growth by MOCVD hydride epitaxy with laser sputtering of antimony

A new method of obtaining quantum-size GaAs_1−x Sb_x (x⩽0.45) layers is proposed. The method consists in laser vaporization of solid metallic antimony near the substrate directly in the reactor. The antimony concentration is set by the antimony sputtering time with the arsine flux shut off. The polarization of the photoluminescence of the obtained layers indicates the formation of quantum wires. The heterostructures obtained are used to fabricate laser diodes. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 84–88 (10 July 1998)     

Spectral Analysis of Differential Operators with Involution and Operator Groups

We study the spectral properties of differential operators with involution of the following two types: operators with involution multiplying the potential and operators with involution multiplying the derivative. The similar operator method is used to obtain a refined asymptotics of the eigenvalues and eigenvectors of such operators. These asymptotics are used to derive asymptotic formulas for the operator groups generated by the operators in question. These operator groups can be used to describe mild solutions of the corresponding mixed problems.     

Spectral Properties of Classical Dirac Operators and Operators with Involution in Homogeneous Function Spaces

Differential Equations - We present spectrum localization theorems for Dirac operators and operators with involution in a class of function spaces introduced in [Contemp. Math., 2018, vol. 706, pp....     

On the spectral properties of a second-order differential operator with a matrix potential

By applying the method of similar operators to a second-order differential operator with a matrix potential and semiperiodic boundary conditions, we obtain asymptotic estimates for the weighted mean eigenvalue and spectral projections and prove the equiconvergence of spectral expansions.     

Investigation of the spatial orientation of the hydroxy group and the intramolecular hydrogen bond in stereoisomeric 2,9-dimethyl- and 1,2,9-trimethyldecahydro-4-quinolols and their 4-ethynyl-substituted derivatives by IR spectroscopy

The spatial orientation of the hydroxy group in stereoisomeric 2,9-dimethyl- and 1,2,9-trimethyldecahydro-4-quinolols and their 4-ethynyl-substituted derivatives was established by IR spectroscopy. The formation of an intramolecular hydrogen bond in the equatorial isomers of trans- and cis-2,9-dimethyl- and 1,2,9-trimethyldecahydro-4-quinolols and cis-2,9-dimethyl- and 1,2,9-trimethyl-4-ethynyldecahydro-4-quinolols, which leads to a small degree of distortion of the chair conformation of the heteroring, was demonstrated. The enthalpy of formation of the hydrogen bond was calculated. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 796–800, June, 1980.     

Dielectric and Thermal Properties of KNO3 Encapsulated in Carbon Nanotubes

Physics of the Solid State - The results of the study of phase transitions of KNO3 encapsulated in carbon nanotubes are presented. It is shown that the temperature range of existence of KNO3...