99 research outputs found
Phase transitions in exactly solvable decorated model of localized Ising spins and itinerant electrons
A hybrid lattice-statistical model of doubly decorated two-dimensional
lattices, which have localized Ising spins at its nodal sites and itinerant
electrons delocalized over decorating sites, is exactly solved with the help of
a generalized decoration-iteration transformation. Under the assumption of a
quarter filling of each couple of the decorating sites, the ground state
constitutes either spontaneously long-range ordered ferromagnetic or
ferrimagnetic phase in dependence on whether the ferromagnetic or
antiferromagnetic interaction between the localized Ising spins and itinerant
electrons is considered. The critical temperature of the spontaneously
long-range ordered phases monotonically increases upon strengthening the ratio
between the kinetic term and the Ising-type exchange interaction.Comment: 4 pages, 3 figures, presented at International Conference on
Magnetism 2009 to be held on July 26-31 in Karlsruhe, Germany. submitted to
J. Phys.: Conf. Se
Spontaneous order in the highly frustrated spin-1/2 Ising-Heisenberg model on the triangulated Kagome lattice due to the Dzyaloshinskii-Moriya anisotropy
The spin-1/2 Ising-Heisenberg model on the triangulated Kagome
(triangles-in-triangles) lattice is exactly solved by establishing a precise
mapping correspondence to the simple spin-1/2 Ising model on Kagome lattice. It
is shown that the disordered spin liquid state, which otherwise occurs in the
ground state of this frustrated spin system on assumption that there is a
sufficiently strong antiferromagnetic intra-trimer interaction, is eliminated
from the ground state by arbitrary but non-zero Dzyaloshinskii-Moriya
anisotropy.Comment: 4 pages, 3 figures, to be presented at conference Highly Frustrated
Magnetism, 7-12 September 2008, Braunschweig, German
Effect of the Canting of Local Anisotropy Axes on Ground-State Properties of a Ferrimagnetic Chain with Regularly Alternating Ising and Heisenberg Spins
The effect of the canting of local anisotropy axes on the ground-state phase
diagram and magnetization of a ferrimagnetic chain with regularly alternating
Ising and Heisenberg spins is exactly examined in an arbitrarily oriented
magnetic field. It is shown that individual contributions of Ising and
Heisenberg spins to the total magnetization basically depend on the spatial
orientation of the magnetic field and the canting angle between two different
local anisotropy axes of the Ising spins.Comment: 3 pages, 3 figure
Thermodynamic properties of a tetramer ferro-ferro-antiferro-antiferromagnetic Ising-Heisenberg bond alternating chain as a model system for Cu(3-Clpy)(N)
Thermodynamic properties of a tetramer
ferro-ferro-antiferro-antiferromagnetic Ising-Heisenberg bond alternating chain
are investigated by the use of an exact mapping transformation technique. Exact
results for the magnetization, susceptibility and specific heat in the zero as
well as nonzero magnetic field are presented and discussed in detail. The
results obtained from the mapping are compared with the relevant experimental
data of Cu(3-Clpy)(N) (3-Clpy=3-Chloropyridine).Comment: 10 pages, 1 table, 14 figures, to be presented at CSMAG04 conferenc
Multiple frustration-induced plateaus in a magnetization process of the mixed spin-1/2 and spin-3/2 Ising-Heisenberg diamond chain
Magnetization process of the mixed spin-1/2 and spin-3/2 Ising-Heisenberg
diamond chain is examined by combining three exact analytical techniques: Kambe
projection method, decoration-iteration transformation and transfer-matrix
method. Multiple frustration-induced plateaus in a magnetization process of
this geometrically frustrated system are found provided that a relative ratio
between the antiferromagnetic Heisenberg- and Ising-type interactions exceeds
some particular value. By contrast, there is just a single magnetization
plateau if the frustrating Heisenberg interaction is sufficiently small
compared to the Ising one.Comment: 4 pages, 1 figure, presented at International Conference on Highly
Frustrated Magnetism (HFM 2008), 7-12 September, 2008, Braunschweig, Germany,
to be published in Journal of Physics: Conference Serie
Spin-1/2 Ising-Heisenberg model with the pair XYZ Heisenberg interaction and quartic Ising interactions as the exactly soluble zero-field eight-vertex model
The spin-1/2 Ising-Heisenberg model with the pair XYZ Heisenberg interaction
and quartic Ising interactions is exactly solved by establishing a precise
mapping relationship with the corresponding zero-field (symmetric) eight-vertex
model. It is shown that the Ising-Heisenberg model with the ferromagnetic
Heisenberg interaction exhibits a striking critical behavior, which manifests
itself through re-entrant phase transitions as well as continuously varying
critical exponents. The changes of critical exponents are in accordance with
the weak universality hypothesis in spite of a peculiar singular behavior to
emerge at a quantum critical point of the infinite order, which occurs at the
isotropic limit of the Heisenberg interaction. On the other hand, the
Ising-Heisenberg model with the antiferromagnetic Heisenberg interaction
surprisingly exhibits less significant changes of both critical temperatures as
well as critical exponents upon varying a strength of the exchange anisotropy
in the Heisenberg interaction.Comment: 11 pages, 9 figure
Potts and percolation models on bowtie lattices
We give the exact critical frontier of the Potts model on bowtie lattices.
For the case of , the critical frontier yields the thresholds of bond
percolation on these lattices, which are exactly consistent with the results
given by Ziff et al [J. Phys. A 39, 15083 (2006)]. For the Potts model on
the bowtie-A lattice, the critical point is in agreement with that of the Ising
model on this lattice, which has been exactly solved. Furthermore, we do
extensive Monte Carlo simulations of Potts model on the bowtie-A lattice with
noninteger . Our numerical results, which are accurate up to 7 significant
digits, are consistent with the theoretical predictions. We also simulate the
site percolation on the bowtie-A lattice, and the threshold is
. In the simulations of bond percolation and site
percolation, we find that the shape-dependent properties of the percolation
model on the bowtie-A lattice are somewhat different from those of an isotropic
lattice, which may be caused by the anisotropy of the lattice.Comment: 18 pages, 9 figures and 3 table
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