3 research outputs found
An exact solution on the ferromagnetic Face-Cubic spin model on a Bethe lattice
The lattice spin model with --component discrete spin variables restricted
to have orientations orthogonal to the faces of -dimensional hypercube is
considered on the Bethe lattice, the recursive graph which contains no cycles.
The partition function of the model with dipole--dipole and
quadrupole--quadrupole interaction for arbitrary planar graph is presented in
terms of double graph expansions. The latter is calculated exactly in case of
trees. The system of two recurrent relations which allows to calculate all
thermodynamic characteristics of the model is obtained. The correspondence
between thermodynamic phases and different types of fixed points of the RR is
established. Using the technique of simple iterations the plots of the zero
field magnetization and quadrupolar moment are obtained. Analyzing the regions
of stability of different types of fixed points of the system of recurrent
relations the phase diagrams of the model are plotted. For the phase
diagram of the model is found to have three tricritical points, whereas for there are one triple and one tricritical points.Comment: 20 pages, 7 figure
Magnetic and quantum entanglement properties of the distorted diamond chain model for azurite
We present the results of magnetic properties and entanglement of the
distorted diamond chain model for azurite using pure quantum exchange
interactions. The magnetic properties and concurrence as a measure of pairwise
thermal entanglement have been studied by means of variational mean-field like
treatment based on Gibbs-Bogoliubov inequality. Such a system can be considered
as an approximation of the natural material azurite, Cu3(CO3)2(OH)2. For values
of exchange parameters, which are taken from experimental results, we study the
thermodynamic properties, such as azurite specific heat and magnetic
susceptibility. We also have studied the thermal entanglement properties and
magnetization plateau of the distorted diamond chain model for azurite