77 research outputs found
On the Ising-Heisenberg model with the doubly decorated network structure I
Using an exact mapping transformation method, magnetic properties of a
spin-1/2 and spin-1 doubly decorated Ising-Heisenberg model are investigated in
detail. By assuming that both interaction parameters are ferromagnetic, we
found in addition to an usual ferromagnetic phase another two phases with a
nontrivial long-range order.Comment: 3 pages, 2 figures, to be presented at conference ICM 200
Rise and Fall of Reentrant Phase Transitions in a Coupled Spin-Electron Model on a Doubly Decorated Honeycomb Lattice
Phase diagrams and spontaneous magnetization are rigorously calculated for a
coupled spin-electron model on a doubly decorated honeycomb lattice, which
accounts for a quantum-mechanical hopping of the mobile electrons on decorating
sites, the nearest-neighbor Ising coupling between mobile electrons and
localized spins, as well as, the further-neighbor Ising coupling between the
localized spins placed on nodal sites. The spontaneously ordered ferromagnetic
phase, spontaneously ordered antiferromagnetic phase and disordered
paramagnetic phase emerge in a phase diagram depending on an electron filling
of the decorating sites, a relative size of the hopping term and both
considered coupling constants. It is evidenced that a nature and size of the
further-neighbor Ising coupling between the localized spins basically
influences rise and fall of reentrant transitions close to a phase boundary
between the paramagnetic phase and both spontaneously ordered phases.Comment: 5 figure
Ground state, magnetization process and magnetocaloric effect of the exactly tractable spin-electron tetrahedral chain
A hybrid spin-electron system on one-dimensional tetrahedral chain, in which
the localized Ising spin regularly alternates with the mobile electron
delocalized over three lattice sites, is exactly investigated using the
generalized decoration-iteration transformation. The system exhibits either the
ferromagnetic or antiferromagnetic ground state depending on whether the
ferromagnetic or antiferromagnetic interaction between the Ising spins and
mobile electrons is considered. The enhanced magnetocaloric effect during the
adiabatic demagnetization suggests a potential use of the investigated system
for low-temperature magnetic refrigeration.Comment: 3 pages, 4 figures, contribution to proceedings of The European
Conference PHYSICS OF MAGNETISM 2014 (PM'14) in Poznan, Polan
- …