3,100 research outputs found
Magnetization plateaux in the classical Shastry-Sutherland lattice
We investigated the classical Shastry-Sutherland lattice under an external
magnetic field in order to understand the recently discovered magnetization
plateaux in the rare-earth tetraborides compounds RB. A detailed study of
the role of thermal fluctuations was carried out by mean of classical spin
waves theory and Monte-Carlo simulations. Magnetization quasi-plateaux were
observed at 1/3 of the saturation magnetization at non zero temperature. We
showed that the existence of these quasi-plateaux is due to an entropic
selection of a particular collinear state. We also obtained a phase diagram
that shows the domains of existence of different spin configurations in the
magnetic field versus temperature plane.Comment: 4 pages, proceedings of HFM200
Quantum kagome antiferromagnet in a magnetic field: Low-lying non-magnetic excitations versus valence-bond crystal order
We study the ground state properties of a quantum antiferromagnet on the
kagome lattice in the presence of a magnetic field, paying particular attention
to the stability of the plateau at magnetization 1/3 of saturation and the
nature of its ground state. We discuss fluctuations around classical ground
states and argue that quantum and classical calculations at the harmonic level
do not lead to the same result in contrast to the zero-field case. For spin
S=1/2 we find a magnetic gap below which an exponential number of non-magnetic
excitations are present. Moreover, such non-magnetic excitations also have a
(much smaller) gap above the three-fold degenerate ground state. We provide
evidence that the ground state has long-range order of valence-bond crystal
type with nine spins in the unit cell.Comment: 5 pages including 4 figures, uses REVTeX4; final version with some
small extensions; to appear in Phys. Rev.
Symbolic capital as a resource of promotion of provincial cities: An analysis of place branding strategies of ural urban destinations
The article analyzes the concept of the symbolic capital of a territory and substantiates the importance of its identification and its use for the promotion of three provincial cities in Russia: Shadrinsk, Chebarkul, and Chelyabinsk. Based on the approach of symbolic interactionism and the use of semiotic analysis, the authors of the article propose to group the resources of the symbolic capital of a territory in three ways. They use signs or symbols, images of the territory, and archetypes. The capital of a provincial city can be perceived symbolically both by external (investors and tourists) and internal (local residents) audiences. They serve as a means of shaping the image and reputation of the place. Both P. Bourdieu’s concept of symbolic capital and V. Radaev’s classification for different types of capital allow us to give examples of conversion from the cultural resources of a territory into symbolic capital. The analysis of the communication resonance of a particular mega event (the meteorite fall on the territory of the Southern Urals in 2013) and the study of cultural heritage of the provincial Russian city of Shadrinsk make it possible to identify the actual directions for converting the intangible resources of cities into their symbolic capital. © 2020, FB and Media Group of Estonian Literary Museum. All rights reserved
Magnetization Process of the Classical Heisenberg Model on the Shastry-Sutherland Lattice
We investigate classical Heisenberg spins on the Shastry-Sutherland lattice
and under an external magnetic field. A detailed study is carried out both
analytically and numerically by means of classical Monte-Carlo simulations.
Magnetization pseudo-plateaux are observed around 1/3 of the saturation
magnetization for a range of values of the magnetic couplings. We show that the
existence of the pseudo-plateau is due to an entropic selection of a particular
collinear state. A phase diagram that shows the domains of existence of those
pseudo-plateaux in the plane is obtained.Comment: 9 pages, 11 figure
High-Order Coupled Cluster Method Study of Frustrated and Unfrustrated Quantum Magnets in External Magnetic Fields
We apply the coupled cluster method (CCM) in order to study the ground-state
properties of the (unfrustrated) square-lattice and (frustrated)
triangular-lattice spin-half Heisenberg antiferromagnets in the presence of
external magnetic fields. Here we determine and solve the basic CCM equations
by using the localised approximation scheme commonly referred to as the
`LSUB' approximation scheme and we carry out high-order calculations by
using intensive computational methods. We calculate the ground-state energy,
the uniform susceptibility, the total (lattice) magnetisation and the local
(sublattice) magnetisations as a function of the magnetic field strength. Our
results for the lattice magnetisation of the square-lattice case compare well
to those results of QMC for all values of the applied external magnetic field.
We find a value for magnetic susceptibility of for the
square-lattice antiferromagnet, which is also in agreement with the results of
other approximate methods (e.g., via QMC). Our estimate for the
range of the extent of the () magnetisation plateau for the
triangular-lattice antiferromagnet is , which is in good
agreement with results of spin-wave theory () and
exact diagonalisations (). The CCM value for the
in-plane magnetic susceptibility per site is , which is below the
result of the spin-wave theory (evaluated to order 1/S) of .Comment: 30 pages, 13 figures, 1 Tabl
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Hubbard ladders in a magnetic field
The behavior of a two leg Hubbard ladder in the presence of a magnetic field is studied by means of Abelian bosonization. We predict the appearance of a new (doping dependent) plateau in the magnetization curve of a doped 2-leg spin ladder in a wide range of couplings. We also discuss the extension to N-leg Hubbard ladders
Coupled Ising models with disorder
In this paper we study the phase diagram of two Ising planes coupled by a
standard spin-spin interaction with bond randomness in each plane. The whole
phase diagram is analyzed by help of Monte Carlo simulations and field theory
arguments.Comment: 9 pages and 3 figure
Magnetization plateaux in the classical shastry-sutherland lattice
We investigated the classical Shastry-Sutherland lattice under an external magnetic field in order to understand the recently discovered magnetization plateaux in the rare-earth tetraborides compounds RB4. A detailed study of the role of thermal fluctuations was carried out by mean of classical spin waves theory and Monte-Carlo simulations. Magnetization quasi- plateaux were observed at 1=3 of the saturation magnetization at non zero temperature. We showed that the existence of these quasi-plateaux is due to an entropic selection of a particular collinear state. We also obtained a phase diagram that shows the domains of existence of different spin configurations in the magnetic field versus temperature plane.Departamento de Físic
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