Suchergebnisse

Makhnev and Samoilenko have found parameters of strongly regular graphs with no more than 1000 vertices, which may be neighborhoods of vertices in antipodal distance-regular graph of diameter 3 and with λ=μ. They proposed the program of investigation vertex-symmetric antipodal distance-regular graphs of diameter 3 with λ=μ, in which neighborhoods of vertices are strongly regular. In this paper we consider neighborhoods of vertices with parameters (25,8,3,2). ; This work is partially supported by RSF, project 14-11-00061-P (Theorem 1) and by the program of the government support of leading universities of Russian Federation, agreement 02.A03.21.0006 from 27.08.2013 (Corollary 1).

The role of actors of the innovation process and the role of government in creating congenial innovation climate in the region are considered in the article. A project approach in order to solve problems of regional development is proposed in the article

WTe2 and MoTe2 single crystals were grown, and their electrical resistivity in the temperature range from 80 K to 300 K, optical properties at room temperature in the spectral range of 0.17-5.0 eV were studied as well as theoretical calculations of the electronic structure were performed. It is shown that the temperature dependence of the electrical resistivity of orthorhombic WTe2 has a metallic type with resistivity value of (0.5-1) mOhmcm, while hexagonal MoTe2 has a semiconductor one and resistivity value (0.5-1) Ohmcm, which is three orders of magnitude larger than the resistivity of WTe2. Optical properties indicated that there is no contribution from free carriers in the entire spectral range studied. The calculated densities of the electronic states of MoTe2 and WTe2 showed the presence of a bunch of the molybdenum and tungsten electronic states in a wide energy interval with strong admixing of tellurium states. In the WTe2 compound, the larger number of the electronic states is located near the Fermi energy, characterizing a more metallic state in this compound as compared to MoTe2. © Published under licence by IOP Publishing Ltd. ; Government Council on Grants, Russian Federation: 02, 211 ; Russian Foundation for Basic Research, RFBR: 17-52-52008 ; Ministry of Education and Science of the Russian Federation, Minobrnauka: АААА-А18-118020190098-5 ; The research was carried out within the state assignment of Ministry of Education and Science of the Russian Federation (theme "Spin" No. АААА-А18-118020290104-2 and theme "Electron" No. АААА-А18-118020190098-5), supported in part by RFBR (Project No. 17-52-52008) and the Government of Russian Federation (Decree No. 211, Contract No. 02.A03.21.0006).

The effect of quenching on the electrical resistivity and optical properties of MoTe2 compound was studied. Significant changes were detected in the behaviour and value of the electrical resistivity, indicating an increase in the metallic (conductive) properties of the compound, which is in good agreement with the data of optical measurements. © 2019 Published under licence by IOP Publishing Ltd. ; Government Council on Grants, Russian Federation: 211 ; Russian Foundation for Basic Research, RFBR: 17-52-52008 ; Ministry of Education and Science of the Russian Federation, Minobrnauka: АААА-А18-118020190098-5 ; The research was carried out within the state assignment of the Ministry of Education and Science of the Russian Federation (theme "Spin", No. АААА-А18-118020290104-2, and theme "Electron", No. АААА-А18-118020190098-5), supported in part by RFBR (Project No. 17-52-52008) and the Government of Russian Federation (Decree No. 211, Contract No. 02.A03.21.0006).

A topological semimetal PtSn4 single crystal was grown by method of crystallization from a solution in a melt. Then the electrical resistivity and galvanomagnetic properties (magnetoresistivity and the Hall effect) were studied in the temperature range from 4.2 to 80 K and in magnetic fields up to 100 kOe. The optical measurements were carried out at room temperature. The residual resistivity is shown to be low enough and amount to ∼ 0.5 μOhm•cm. The temperature dependence of the electrical resistivity has a metallic type, increasing monotonically with temperature. A sufficiently large magnetoresistance of 750% is observed. The majority carriers are supposed to be holes with a concentration of ∼ 6.8•10 21 cm -3 and mobility of ∼ 1950 cm 2 /Vs at T = 4.2 K as a result of the Hall effect studies. The optical properties of PtSn 4 have features characteristic of "bad" metals. © 2019 Published under licence by IOP Publishing Ltd. ; This work was partly supported by the state assignment of Russia (theme "Spin" No. АААА-А18-18020290104-2 and theme "Electron" No. АААА-А18-118020190098-5), by the RFBR (project No.17-52-52008) and by the Government of the Russian Federation (state contract No. 02.A03.21.0006).