110 research outputs found
Proximity effect in atomic-scaled hybrid superconductor/ferromagnet structures: crucial role of electron spectra
We study the influence of the configuration of the majority and minority spin
subbands of electron spectra on the properties of atomic-scaled
superconductor-ferromagnet S-F-S and F-S-F hybrid structures. At low
temperatures, the S/F/S junction is either a 0 or junction depending on the
energy shift between S and F materials and the anisotropy of the Fermi
surfaces. We found that the spin switch effect in F/S/F system can be reversed
if the minority spin electron spectra in F metal is of the hole-like type
Critical Current Oscillations in Strong Ferromagnetic Pi-Junctions
We report magnetic and electrical measurements of Nb Josephson junctions with
strongly ferromagnetic barriers of Co, Ni and Ni80Fe20 (Py). All these
materials show multiple oscillations of critical current with barrier thickness
implying repeated 0-pi phase-transitions in the superconducting order
parameter. We show in particular that the Co barrier devices can be accurately
modelled using existing clean limit theories and so that, despite the high
exchange energy (309 meV), the large IcRN value in the pi-state means Co
barriers are ideally suited to the practical development of superconducting
pi-shift devices.Comment: 4 pages 3 figures 1 table. Revised version as accepted for
publication. To appear in Physical Review Letter
Formation of the microstructure of rapidly solidified alloys for the system Sn-Bi
The results of microstructural study of rapidly solidified Sn-Bi alloys obtained at the melt cooling rate of 105 K/s with the compositions of Sn-X wt. % Bi (X = 13, 20, 30, 43) are presented. Microstructural studies are carried out using scanning electron microscopy; a grain structure is analyzed by an electron backscatter diffraction technique. It is found out that the crystallization of all investigated alloys proceeds by a chemically partionless mechanism which results in the formation of a supersaturated solid solution of bismuth in a tin lattice with the original composition. Observations of the solid solution decomposition process at room temperature shows that decomposition proceeds by both continuous and discontinuous mechanisms in alloys with bismuth concentration not higher than the limit of solubility of bismuth in a tin (20 wt. %). Needle-like coherent bismuth inclusions are formed in the volume of a tin grain as a result of continuous decomposition. Discontinuous decomposition rate increases with the increasing concentration of bismuth in the alloy. In hipoeutectic alloys with bismuth concentration higher than the solubility limit, decomposition occurs by discontinuous mechanism. Complete decomposition proceeds by several stages and results in formation of areas with different degrees of microstructure fineness
Evolution of the local superconducting density of states in ErRhB close to the ferromagnetic transition
We present local tunneling spectroscopy experiments in the superconducting
and ferromagnetic phases of the reentrant superconductor ErRhB. The
tunneling conductance curves jump from showing normal to superconducting
features within a few mK close to the ferromagnetic transition temperature,
with a clear hysteretic behavior. Within the ferromagnetic phase, we do not
detect any superconducting correlations. Within the superconducting phase we
find a peculiar V-shaped density of states at low energies, which is produced
by the magnetically modulated phase that coexists with superconductivity just
before ferromagnetism sets in.Comment: 5 pages, 4 figure
Properties of tunnel Josephson junctions with a ferromagnetic interlayer
We investigate superconductor/insulator/ferromagnet/superconductor (SIFS)
tunnel Josephson junctions in the dirty limit, using the quasiclassical theory.
We formulate a quantitative model describing the oscillations of critical
current as a function of thickness of the ferromagnetic layer and use this
model to fit recent experimental data. We also calculate quantitatively the
density of states (DOS) in this type of junctions and compare DOS oscillations
with those of the critical current.Comment: 9 pages, 8 figures, to be published in Phys. Rev.
Issues of financial assurance of economy greening in the regions
The relevance of the analyzed issue is caused by the need to internalize environmental externalities in the modern world. The purpose of the article is to examine the issue of financial support of the green economy using the example of the regions included in the Volga Federal District (VFD). The leading methods to the study of this issue is a comparative analysis of environmental taxes and charges in Russia and countries of the European Union (EU) and the analysis of environmental problems in the regions of the Volga Federal District, which allow identifying the shortcomings of the existing environmental payment system and proposing measures to modernize the system of financial support of the green economy. The key shortcomings of the existing environmental payment system: low rates of environmental payments; the inappropriate use of funds received from environmental payments; concentration of 97% of revenues from environmental payments in the federal budget. The contents of the article may be helpful for public authorities of general and special competence to develop the principal directions of environmental policy and plan activities aimed at improving the green economy. © 2016 Shekhova et al
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