4,003 research outputs found
The Neel temperature and sublattice magnetization for the stacked triangular-lattice antiferromagnet with a weak interlayer coupling
The quantum Heisenberg antiferromagnet on the stacked triangular lattice with
the intralayer nearest-neighbor exchange interaction J and interlayer exchange
J' is considered within the non-linear -model with the use of the
renormalization group (RG) approach. For J' << J the asymptotic formula for the
Neel temperature and sublattice magnetization are obtained. RG turns
out to be insufficient to describe experimental data since it does not take
into account the -vortices. Therefore is estimated
using the Monte-Carlo result for the 2D correlation length [10] which has a
Kosterlitz-type behavior near the temperature where the vortices are
activated.Comment: 4 pages, 1 figur
Strong fluctuations near the frustration point in cubic lattice ferromagnets with localized moments
Thermodynamic properties of cubic Heisenberg ferromagnets with competing
exchange interactions are considered near the frustration point where the
coefficient in the spin-wave spectrum
vanishes. Within the Dyson-Maleev formalism it is found that at low
temperatures thermal fluctuations stabilize ferromagnetism by increasing the
value of . For not too strong frustration this leads to an unusual "concave"
shape of the temperature dependence of magnetization, which is in agreement
with experimental data on the europium chalcogenides. The phase diagram is
constructed by means of Monte Carlo simulation, and suppression of
magnetization and Curie temperature is found in comparison with the results of
the spin-wave theory. This effect is explained by the the presence of
non-analytical corrections to the spin-wave spectrum which are represented in
the lowest order by the term .Comment: 5 pages, 5 figures; updated versio
Realization of anisotropic compass model on the diamond lattice of Cu in CuAlO
Spin-orbit (SO) Mott insulators are regarded as a new paradigm of magnetic
materials, whose properties are largely influenced by SO coupling and featured
by highly anisotropic bond-dependent exchange interactions between the
spin-orbital entangled Kramers doublets, as typically manifested in
iridates. Here, we propose that a very similar situation can be realized in
cuprates when the Cu ions reside in a tetrahedral environment, like in
spinel compounds. Using first-principles electronic structure calculations, we
construct a realistic model for the diamond lattice of the Cu ions in
CuAlO and show that the magnetic properties of this compound are
largely controlled by anisotropic compass-type exchange interactions that
dramatically modify the magnetic ground state by lifting the spiral spin-liquid
degeneracy and stabilizing a commensurate single- spiral
Assessment of the Size of Rocks in Benchs and Lumpiness of the Blasted Mountain Mass on Pits with Use of Gis Geomix
On the basis of natural researches in career of SC Kovdorsky MCP and computer processing of their results in GIS GEOMIX was developed the photometric method of assessment of blocks (sizes) of breeds in the slope of ledges of a pit, the existing version of this method intended for assessment of lumpiness of mountain mass is improve
Integral pattern of bench stability on all adjacent rock of open-pit mine in solid rocks
The article presents the integrated image of bench stability across the entire adjacent pit area on the basis of a probabilistic method to predict the azimuthangular parameters of cracks that limit the potential prisms of the pit bench collapse that are put in the final position, as well as those planned to be set to the limiting contour in the form of a software component as the part of the specialized geoinformation GIS system "Stability
Strong short-range magnetic order in a frustrated FCC lattice and its possible role in the iron structural transformation
We investigate magnetic properties of a frustrated Heisenberg antiferromagnet
with a face-centered cubic (FCC) lattice and exchange interactions between the
nearest- and next-nearest neighbours, J1 and J2. In a collinear phase with the
wave vector Q = (pi,pi,pi) the equations of the self-consistent spin-wave
theory for the sublattice magnetization and the average short range order
parameter are obtained and numerically solved. The dependence of the Neel
temperature T_N on the ratio J2/J1 is obtained. It is shown, that at strong
enough frustration there is a wide temperature region above T_N with strong
short range magnetic order. Application of this result to description of
structural phase transition between alpha and gamma-phase of Fe is considered
Algal and cyanobacterial diversity in saline rivers of the Elton Lake Basin (Russia) studied via light microscopy and next-generation sequencing
Naturally saline rivers are known in various regions of the world. Saline rivers with a salinity gradient from the source to the mouth are particularly interesting, because the range of salinity is the structure-forming factor of the hydrobiont assemblage. Such rivers are represented by saline rivers of the Elton Lake Basin in Volgograd region of Russia (the Bolshaya Samoroda River and the Malaya Samoroda River). Herein, we analyzed taxonomic structure and species diversity of microalgae and Cyanobacteria of the saline rivers flowing into the Elton Lake by light microscopy and next-generation sequencing. The differences and possible causes of inconsistencies in the results obtained by these methods are discussed. In total, 91 taxa of microorganisms were identified by integrated approach in the assemblages of microalgae and Cyanobacteria in the middle course of the Bolshaya Samoroda River, and 60 taxa – in the river mouth. The species diversity of those assemblages in the hypersaline Malaya Samoroda River was lower: 27 taxa from the middle course and 23 taxa from the mouth. Next-generation sequencing allowed us to refine and expand the list of microalgae taxa in the studied saline rivers due to detection of species which were hard to identify, low-abundance taxa, as well as extremely small-cell forms. Some discrepancies between the data obtained by light microscopy and next-generation sequencing indicate the advantage of simultaneous use of both methods for study of the algae communities. Such a comprehensive approach provides the most accurate and correct list of taxa added with the morphological descriptions and 18S rRNA and 16S rRNA partial sequences. Generally, 18 taxa have been recorded for the first time in the Bolshaya Samoroda River, belonging to the phyla Chlorophyta (Borodinellopsis sp., Chlorochytrium lemnae Cohn, Caespitella sp., Halochlorococcum sp., Tetraselmis cordiformis (H. J. Carter) F. Stein), Ochrophyta (Pseudocharaciopsis ovalis (Chodat) D. J. Hibberd, Characiopsis sp., Poterioochromonas stipitata Scherffel, Chrysolepidomonas sp.), Euglenozoa (Euglena bucharica I. Kisselev, Lepocinclis tripteris (Dujardin) B. Marin & Melkonian, Phacus orbicularis K. Hübner, P. parvulus G. A. Klebs), Cryptophyta (Hemiselmis cryptochromatica C. E. Lane & J. M. Archibald, Rhodomonas sp., Hanusia phi J. A. Deane), Haptophyta (Pavlova sp.), Cyanobacteria (Johanseninema constrictum (Szafer) Hasler, Dvorák & Poulícková). Seven taxa have been detected for the first time in the algal and cyanobacterial assemblages of the Malaya Samoroda River from the phyla Chlorophyta (Tetraselmis cordiformis, T. arnoldii (Proschkina-Lavrenko) R. E. Norris, Hori & Chihara, T. tetrathele (West) Butcher, Pyrobotrys elongatus Korshikov), Cryptophyta (Hanusia phi), and Cyanobacteria (Synechococcus elongatus (Nägeli) Nägeli, Oscillatoria simplicissima Gomont)
Voluntary Refusal to Commit a Crime: Significance, General and Special Signs
The article describes and examines the significance of the rule of the voluntary refusal to commit a crime, as well as explores its general and special signs. It is noted that the voluntary refusal to commit a crime is the rule contained in any modern, progressive law. In this vein, there are different theoretical approaches to the determination of its value and signs. The signs are debatable in nature, and their establishment by the law enforcer may cause difficulties. The difference between voluntary refusal to commit a crime, which is implemented in three functions, is determined, definitions of general signs of voluntary refusal are proposed, their content is clarified. Special signs of voluntary refusal are disclosed
Progress Towards Achieving SDG 13 «Combating Climate Change» in Belarus
10995/27938В статье рассмотрено такое глобальное изменение в природе как климат. Климат в Беларуси играет важную роль, так как любая его инверсия не обходится без последствий. Так же в данной статье приведены пути решения проблемы, связанной с преобразованием климата.The article examines such a global change in nature as climate. The climate in Belarus plays an important role, as any inversion of it is not without consequences. This article also provides solutions to the problem of climate change
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