Power factor of very thin thermoelectric layers of different thickness prepared by laser ablation

Room temperature conductivity and the Seebeck coefficient of thin layers prepared by laser ablation from Bi₂Te₃ target were explored. The power factor was calculated for samples prepared at substrate temperature of 360°C with the density of the laser beam 5 J cm⁻² and at substrate temperature of 410°C with the density of the laser beam 2 J cm⁻² during the deposition. Oscillations of the conductivity and the power factor with the layer thickness were observed at room temperature. The oscillations of conductivity were also verified at the temperature of 77 K. The period of oscillations depends on the preparation conditions. This behavior has been theoretically explained by the quantum size effect in the layers containing different phases and in addition, it was demonstrated by the X-ray Diffraction measurement. The behavior of the power factor of the layers is compared to the behavior of the figure of merit of the layers published earlier.     

Path and phase determination for an interfering photon with orbital angular momentum

A polarized photon with well-defined orbital angular momentum that emerges from a Mach-Zehnder interferometer (MZI) is shown to seemingly circumvent wave-particle duality constraints. For certain phase differences between the MZI arms, this pattern yields both reliable which-path information and high phase sensitivity.     

Thermal and non-radiative transitions of electrons at imperfections in ionic crystals

The theory of non-radiative and thermal transitions of electrons at imperfections in ionic crystals is elaborated. The results obtained are used to confirm Mott's and Gurney's theories on the detachment process in two steps of electrons from F centres during the absorption of light in the F band and to explain theoretically the temperature dependence of quantum efficiency. Good agreement with experiment was obtained. The possibility of the luminescence of alkali halide crystals containing F centres at sufficiently low temperatures was also determined.     

The diffusion of the excitation energy in molecular crystals

A theory of the coefficient of diffusion of an exciton in molecular crystals is elaborated, based on the conception of the exciton as the excited state of the molecule of a crystal propagating through the crystal by chance transition from one molecule to another. The theoretical results are compared with the experimental data for an anthracene crystal.     

Knight shift and paramagnetic susceptibility study in U3P4

The Knight shift and paramagnetic susceptibility have been measured on one sample of U₃P₄ in a rather wide temperature region. Observed deviations from the Curie-Weiss law are ascribed to the conduction electrons. The s-f coupling constantΓ=?2·4 eV has been obtained from the experimental data in the approximation of homogeneously polarized conduction electrons.     

Irreducibility of associated matrices

For an n by n matrix A, let K(A) be the associated matrix corresponding to a permutation group (of degree m) and one of its characters. Let D_r(A) be the coefficient of x^m?r in K(A+xI). If A is reducible, then D_r(A) is reducible. If A is irreducible and the character is identically one, then D₁(A) is irreducible. If A is row stochastic and the character is identically one, then D_r(A) is essentially row stochastic. Finally, the results motivate the definition of group induced diagraphs.