286 research outputs found
The topology of systems of hyperspaces determined by dimension functions
Given a non-degenerate Peano continuum , a dimension function
defined on the family of compact subsets of ,
and a subset , we recognize the topological structure
of the system (2^X,\D_{\le\gamma}(X))_{\alpha\in\Gamma}, where is the
hyperspace of non-empty compact subsets of and is the
subspace of , consisting of non-empty compact subsets with
.Comment: 12 page
Nanoskyrmion engineering with -electron materials: Sn monolayer on SiC(0001) surface
Materials with -magnetism demonstrate strongly nonlocal Coulomb
interactions, which opens a way to probe correlations in the regimes not
achievable in transition metal compounds. By the example of Sn monolayer on
SiC(0001) surface, we show that such systems exhibit unusual but intriguing
magnetic properties at the nanoscale. Physically, this is attributed to the
presence of a significant ferromagnetic coupling, the so-called direct
exchange, which fully compensates ubiquitous antiferromagnetic interactions of
the superexchange origin. Having a nonlocal nature, the direct exchange was
previously ignored because it cannot be captured within the conventional
density functional methods and significantly challenges ground state models
earlier proposed for Sn/SiC(0001). Furthermore, heavy adatoms induce strong
spin-orbit coupling, which leads to a highly anisotropic form of the spin
Hamiltonian, in which the Dzyaloshinskii-Moriya interaction is dominant. The
latter is suggested to be responsible for the formation of a nanoskyrmion state
at realistic magnetic fields and temperatures.Comment: 4 pages, supplemental materia
Renormalized spectral function for Co adatom on the Pt(111) surface
The strong Coulomb correlations effects in the electronic structure of
magnetic Co adatom on the Pt(111) surface have been investigated. Using a
realistic five d-orbital impurity Anderson model at low temperatures with
parameters determined from first-principles calculations we found a striking
change of the electronic structure in comparison with the LDA results. The
spectral function calculated with full rotationally invariant Coulomb
interaction is in good agreement with the quasiparticle region of the STM
conductance spectrum. Using the calculated spin-spin correlation functions we
have analyzed the formation of the magnetic moments of the Co impurity
orbitals.Comment: 4 pages, 4 figure
Spatial inversion of gyrotropy parameter in conductivity tensor and charge transport peculiarities
Charge transfer is discussed for the case when gyrotropy parameter (Hall coefficient) varies along transport л-direction and inverses its sign. This situation takes place in contacts of the serially joined materials having electron and hole types of conductivity. Spatial inhomogeneity of conductivity and inversion of Hall coefficient sign are analyzed in terms of electric potential and current density distribution. It is shown that under inhomogeneous magnetic field the steady current skinning takes place in plate sample
Grain yield response of facultative and winter triticale for late autumn sowing in different weather conditions
Climate change is affecting the growing conditions of winter cereals. Peculiarities of
organogenesis and their impact in grain yield of facultative triticale depend on different nitrogen
fertilization can help to avoid adverse effects of unfavorable conditions. Field experiment was
conducted in zone of the Right-Bank Forest-Steppe of Ukraine. The experiment included 2 late
autumns sowing periods and fertilization system with few variants of nitrogen fertilization
applied in spring. Features of organogenesis of two winter varieties and facultative triticale
Pidzimok kharkivskiy were determined by apical meristem microscopy from emergence till
heading. Was established process of apical meristem differentiation in facultative triticale has
non-linear relation between temperature and number of spikelets. The efficiency of apical
meristem differentiation reaches its maximum at 12 °C. Grain yield of triticale varieties depend
on studied factors but main impact had weather conditions. Grain yield of facultative triticale
significantly exceeds winter varieties and had a lesser difference between sowing period than
winter cultivars. Crops in the first sowing period were more productive than in the second.
Facultative triticale has great productivity potential in late autumn sowing and can realize it in
various conditions. Reduced yields in late sowing are lower than in winter cultivars
Hybridization and spin-orbit coupling effects in quasi-one-dimensional spin-1/2 magnet Ba3Cu3Sc4O12
We study electronic and magnetic properties of the quasi-one-dimensional
spin-1/2 magnet Ba3Cu3Sc4O12 with a distinct orthogonal connectivity of CuO4
plaquettes. An effective low-energy model taking into account spin-orbit
coupling was constructed by means of first-principles calculations. On this
basis a complete microscopic magnetic model of Ba3Cu3Sc4O12, including
symmetric and antisymmetric anisotropic exchange interactions, is derived. The
anisotropic exchanges are obtained from a distinct first-principles numerical
scheme combining, on one hand, the local density approximation taking into
account spin-orbit coupling, and, on the other hand, projection procedure along
with the microscopic theory by Toru Moriya. The resulting tensors of the
symmetric anisotropy favor collinear magnetic order along the structural chains
with the leading ferromagnetic coupling J1 = -9.88 meV. The interchain
interactions J8 = 0.21 meV and J5 = 0.093 meV are antiferromagnetic. Quantum
Monte Carlo simulations demonstrated that the proposed model reproduces the
experimental Neel temperature, magnetization and magnetic susceptibility data.
The modeling of neutron diffraction data reveals an important role of the
covalent Cu-O bonding in Ba3Cu3Sc4O12.Comment: 11 pages, 12 figure
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