Electronic structure, magnetic and optical properties of intermetallic compounds R2Fe17 (R=Pr,Gd)

In this paper we report comprehensive experimental and theoretical investigation of magnetic and electronic properties of the intermetallic compounds Pr2Fe17 and Gd2Fe17. For the first time electronic structure of these two systems was probed by optical measurements in the spectral range of 0.22-15 micrometers. On top of that charge carriers parameters (plasma frequency and relaxation frequency) and optical conductivity s(w) were determined. Self-consistent spin-resolved bandstructure calculations within the conventional LSDA+U method were performed. Theoretical interpetation of the experimental s(w) dispersions indicates transitions between 3d and 4p states of Fe ions to be the biggest ones. Qualitatively the line shape of the theoretical optical conductivity coincides well with our experimental data. Calculated by LSDA+U method magnetic moments per formula unit are found to be in good agreement with observed experimental values of saturation magnetization.Comment: 16 pages, 5 figures, 1 tabl

Detection of mechanical resonance of a single-electron transistor by direct current

We have suspended an Al based single-electron transistor whose island can resonate freely between the source and drain leads forming the clamps. In addition to the regular side gate, a bottom gate with a larger capacitance to the SET island is placed underneath to increase the SET coupling to mechanical motion. The device can be considered as a doubly clamped Al beam that can transduce mechanical vibrations into variations of the SET current. Our simulations based on the orthodox model, with the SET parameters estimated from the experiment, reproduce the observed transport characteristics in detail.Comment: 4 pages, 3 figure

Термодинамическая стабильность изомеров моно и дианионов дикарба-нидо-ундекаборатов

The structural and thermodynamic parameters of isomers of mono- and dianions of dicarba-nido-undecaborates were calculated by DFT (B3LYP/6-31G**, B3LYP/6-311+G**, M062X/6-311+G**, PCM/B3LYP/6-311+G**), MP2 (MP2/6-311+G**), G2MP2, G2 approximations.В приближениях B3LYP/6-31G**, B3LYP/6-311+G** M062X/6-311+G**, MP2/6-311+G**, PCM/B3LYP/6-311+G**, G2MP2 и G2 рассчитаны структурные и термодинамические параметры изомеров моно- и дианионов дикарба-нидо-ундекаборатов

Перегруппировки в ряду дикарба-нидо-ундекаборатов

The thermal and chemically initiated thermal rearrangements of dicarba-nido-undecaborates was explored by computational chemistry. It was shown that the kinetic stability of dianions of these compounds is reduced in the series 2,9 > 7,8 > 1,7 > 2,4 > 2,8 > 1,2 >2,7 > 2,3.Методами квантовой химии исследованы термические и химически инициируемые термические пере-группировки изомеров дикарба-нидо-ундекаборатов. Показано, что кинетическая стабильность дианионов этих соединений уменьшается в ряду: 2,9 > 7,8 > 1,7 > 2,4 > 2,8 > 1,2 >2,7 > 2,3

H-alpha Survey of the Local Volume: Isolated Southern Galaxies

We present our H-alpha observations of 11 isolated southern galaxies: SDIG, PGC 51659, E 222-010, E 272-025, E 137-018, IC 4662, Sag DIG, IC 5052, IC 5152, UGCA 438, and E149-003, with distances from 1 to 7 Mpc. We have determined the total H-alpha fluxes from these galaxies. The star formation rates in these galaxies range from 10^{-1} (IC 4662) to 10^{-4}_{\odot}/yr (SDIG) and the gas depletion time at the observed star formation rates lies within the range from 1/6 to 24 Hubble times H_0^{-1} .Comment: 9 pages, 3 figure