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Thermodynamic Properties of Random Transverse Field Mixed Spin
System in the Presence of Single-Ion Anisotropy 总被引:1,自引:0,他引:1
ZHANGYa-Nan YANShi-Lei 《理论物理通讯》2003,40(3):375-380
We study the thermodynamic properties of random transverse field mixed spin system in the presence of single-ion anisotropy on a square lattice. By making use of the effective field theory and a cutting approximation, the detailed phase diagrams are described and some interesting results are found under trimodal random transverse field distribution. A small single-ion anisotropy can magnify magnetic ordering region at low temperatures and existence of a large transverse field can assist the occurrence of reentrant phenomena. With increasing disorder, second-order phase transitions are shown to change into first-order phase transitions. The trajectory of the tricritical point in the phase space as a function of disorder is presented. These indicate a strong correlation with the corresponding to trimodal transverse field distribution. 相似文献
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The trimodal random-field spin-
Ising system in a transverse field is investigated by combining the pair approximation with the discretized path-integral representation by introducing a parameter p to simulate the fractions of the spins not exposed to the external longitudinal magnetic field. The variation of the critical reduced transverse field and longitudinal magnetic field with the parameter p is studied for different coordination numbers and it is found that the system does not exhibit any tricritical points for p>0.22. The phase diagrams with respect to the external longitudinal random-field and the second-order phase transition temperature are obtained for given values of the transverse field, coordination numbers and the parameter p. It is found that for appropriate values of the system parameters the system does present tricritical points and reentrant phase transitions, which may be caused by the competition between the quantum effects and randomness. 相似文献
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We study the thermodynamic properties of random transverse field mixed spin system in the presence ofsingle-ion anisotropy on a square lattice. By making use of the effective field theory and a cutting approximation, thedetailed phase diagrams are described and some interesting results are found under trimodal random transverse fielddistribution. A smallsingle-ion anisotropy can magnify magnetic ordering region at low temperatures and existence ofa large transverse field can assist the occurrence of reentrant phenomena. With increasing disorder, second-order phasetransitions are shown to change into first-order phase transitions. The trajectory of the tricritical point in the phasespace as a function of disorder is presented. These indicate a strong correlation with the corresponding to trimodaltransverse field distribution. 相似文献
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Within the framework of an effective field approximation, the effects of single-ion anisotropy and different trimodal transverse fields of two sublattices on the critical properties of the mixed spin-1/2 and spin-1 Ising system are investigated on the simple cubic lattice. A smaller single-ion anisotropy can magnify magnetic ordering
phases and a larger one can depress magnetic ordering phase for
T-Ω1/2 space at low temperatures, while a smaller single-ion
anisotropy can hardly change the value of critical transverse field for
T-Ω1 space. On the other hand, influences of two different trimodal transverse fields concentrations on tricritical points and magnetic ordering
phases take on some interesting results in T-D space. The main reason
comes from the common action of single-ion anisotropy, different transverse
fields and two trimodal distributions. 相似文献
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The ground-state magnetic properties of the spin-2 transverse Ising model with a longitudinal crystal field are studied within the framework of mean-field theory (MFT) and effective-field theory (EFT), respectively. The phase diagrams and magnetization curves are examined in detail. It is found that the system exhibits a tricritical behavior in the ground-state phase diagrams. Some interesting phenomena have been found, especially the first-order phase transition from one ordered phase to the other ordered phase, which is due to the high spin. The spin correlation has important effect on the magnetic properties of the system. We also find that the ground-state phase diagrams of the spin-2 transverse Ising model are very different from those of the spin-3/2 transverse Ising model. 相似文献
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The spin-
The transverse Ising model with four spin interactions is studied within the finite cluster approximation (FCA), on a honeycomb and a square lattice. We have investigated the influence of the four spin interactions on the phase diagrams of the system and on both longitudinal and transversal magnetizations. We have also shown that the tricritical phenomenon exists only for low values of the transverse field. 相似文献
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Random field spin-S Ising model with a transverse field has been studied by making use of the pair approximation with the discretized path-integral representation, and an analytical expression of second-order phase transition is derived for all the symmetric probability distributions of (longitudinal) random fields. The phase diagrams at T = 0 are obtained, and the conditions for existence of tricritical points are examined for an arbitrary number of nearest-neighbor spins. 相似文献
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The phase diagram of mixed spin-3/2 and spin-2 Ising ferromagnetic model with different single-ion anisotropies is investigated by the use of a mean-field theory based on the Bogoliubov inequality for the Gibbs free energy. Global phase diagrams are obtained in the temperature-anisotropy plane. In particular, by changing values of the single-ion anisotropies, several different types of phase diagrams of first-order transition between two ordered phases, are studied in detail. A variety of multicritical points such as tricritical points, isolated critical points, and triple points are obtained. 相似文献
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A spin-1/2 and spin-3/2 mixed Ising system in a random field is studied by the use of effective-field theory with correlations. The phase diagrams and thermal behaviours of magnetizations are investigated numerically for the honeycomb lattice (z=3) and square lattice (z=4) respectively. The tricritical behaviours for both honeycomb and square lattices, as well as the reentrant behaviour for the square lattice are found. 相似文献
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In this paper, we propose a model to study the thermal and dielectric properties of a monolayer naphthalene-like nanoisland. The ferrielectric mixed spin (1, 7/2) Blume-Capel Ising model has been studied, using Monte Carlo simulations under the Metropolis algorithm. The ground state phase diagrams, in the absence of temperature, are investigated. Moreover, we illustrated the thermal and dielectric properties as a function of temperature, for fixed values of the other parameters. On the other hand, we examine the effects of the exchange coupling interactions on the compensation and blocking temperatures. In addition, we explore the effects of crystal and external longitudinal electric fields on total polarizations. 相似文献
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Erhan Albayrak 《中国物理 B》2017,26(2):20502-020502
The magnetic behaviors of the Fe–Mn–Al alloy are simulated on the Bethe lattice by using a trimodal random bilinear exchange interaction(J) distribution in the Blume–Capel(BC) model. Ferromagnetic(J 0) or antiferromagnetic(J 0)bonds or dilution of the bonds(J = 0) are assumed between the atoms with some probabilities. It is found that the secondor the first-order phase boundaries separate the ferromagnetic(F), antiferromagnetic(AF), paramagnetic(P), or spin-glass(SG) phases from the possible other one. In addition to the tricritical points, the special points at which the second- and the first-order and the spin-glass phase lines meet are also found. Very rich phase diagrams in agreement with the literature are obtained. 相似文献
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Y.F. Zhang 《Physics letters. A》2008,372(15):2696-2700
The phase diagrams and compensation behaviors of mixed spin-1/2 and spin-1 Blume-Capel model in a trimodal magnetic field are investigated in the framework of the effective field theory on simple cubic lattice. The change of negative crystal field and trimodal concentration can affect the TCP, the second-order phase and the magnetic field degeneration at ground state in T-H space. In T-D space, the trajectory of the TCP takes on the acre curve and there exist the two TCPs under certain condition. In addition to giving one or two compensation temperature points in M-T space, the mixed spin Blume-Capel model also provides one or two novel compensation magnetic field points in M-H space. Some results are not revealed in previous works. 相似文献
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Phase diagrams and magnetic properties of the mixed spin-1 and spin-3/2 Ising ferromagnetic thin film: Monte Carlo treatment 下载免费PDF全文
《中国物理 B》2019,(2)
Phase diagrams and magnetic properties of the mixed spin-1 and spin-3/2 Ising film with different single-ion anisotropies are investigated, by the use of Monte Carlo simulation based on heat bath algorithms. The effects of the crystal-fields and the surface coupling on the phase diagrams are investigated in detail and the obtained phase diagrams are presented. Depending on the Hamiltonian parameters, the system exhibits both second-and first-order phase transitions besides tricritical point, triple point, and isolated critical end point. 相似文献
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R. Pirc 《Physics letters. A》1983,94(8):364-366
The existence of a tricritical point is demonstrated for a classical n-vector model with annealed random transverse fields, and the corresponding tricritical temperature Tt and distribution width σt are evaluated within Landau theory for continuous spin dimensionality -2 < n < 10. 相似文献
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A. Jabar 《Phase Transitions》2017,90(11):1112-1120
In this paper, the magnetic properties of ternary mixed spins (σ,S,q) Ising model on a dendrimer nanostructure are studied using Monte Carlo simulations. The ground state phase diagrams of dendrimer nanostructure with ternary mixed spins σ = 1/2, S = 1 and q = 3/2 Ising model are found. The variation of the thermal total and partial magnetizations with the different exchange interactions, the external magnetic fields and the crystal fields have been also studied. The reduced critical temperatures have been deduced. The magnetic hysteresis cycles have been discussed. In particular, the corresponding magnetic coercive filed values have been deduced. The multiples hysteresis cycles are found. The dendrimer nanostructure has several applications in the medicine. 相似文献