Mean-field solution of the mixed spin-1 and spin- Ising system with different single-ion anisotropies

The Effect of a Random Crystal-Field on the Mixed Ising Spins (1/2, 3/2)

“…2d, the system exhibits two first-order transition lines, at very low temperature, terminated by two isolated critical points: the first at d = −1, t = 0.11 and the second located at d = 2 , m S = 1), respectively. It is worthwhile to note that our results concerning the appearance, at low temperature, of first-order transition line terminated by an isolated critical point is in agreement with other works as MFA [6] and Monte Carlo [32,33]. To give more details concerning the first-order transition lines, the free energy and entropy of the system are calculated at low temperature.…”

“…In fact, crystal-field interaction effects on the transition temperature have been investigated by several methods such as effective field theory [1][2][3][4], finite cluster approximation [5], mean field theory [6], MigdalKadanof renormalisation group method [7] and cluster variational method [8]. Nevertheless, some disagreements between theoretical studies, such as the existence of tricritical points, have occurred.…”

The Possibility of Many Compensation Points in a Mixed-Spin Ising Ferrimagnetic System

“…The central idea of the mean-field theory is very simple: we treat the nearest neighbour Ising model in zero field on a lattice containing two sublattices , having sites, each site 2 ISRN Condensed Matter Physics having nearest neighbour. The Hamiltonian of the system in a zero field, with = 3/2 and = 5/2, can be written as follows [3,9]:…”

“…Important advance has been directed to the two-sublattice mixed-spin systems with single-ion anisotropies. These systems have been investigated by a variety of techniques, such as exact, mean-field approximation, and effective field theory [3][4][5][6]. For example, the authors [3] have investigated one constituent having spin-1 and the other constituent having spin-3/2.…”

“…In the first type, the spin compensation temperature of the system ( ) can be obtained by requiring the total magnetization to be equal to zero for various values of anisotropies though the reduced magnetization of the sublattices forming the system is not equal to zero [3,[7][8][9][10]. The second class of work is the phase transitions which demand the Landau expansion of the free energy in the order parameter [3,8,11]. However, we firstly determine the ground-state phase diagram and study sublattice magnetizations of the mixed-spin ferrimagnetic Ising system with various values of the anisotropies on the basis of the mean-field theory.…”