Monte Carlo simulation of a mixed spin 2 and spin Ising ferrimagnetic system

Abstract

The critical behaviour of a mixed ferrimagnetic Ising system on a square lattice in which the two interpenetrating square sublattices have spins σ (± 1 2 ) and S (±2, ±1, 0) has been studied. We carried out exact ground state calculations and performed Monte Carlo simulations to obtain the finite-temperature phase diagram of the model. We found that the system that includes only a nearest-neighbour interaction and the crystal field does not have a compensation point. Also, our study seems to indicate that, contrary to effective-field predictions, there is no tricritical point at nonzero temperature for this model; however a more elaborate analysis will be needed to draw a definite conclusion on this point.

The critical behaviors and the phase diagram of the mixed spin‐1/2 and spin‐2 Ising system on the Bethe lattice

“…While these lines start from about q d ¥ where d = -0.5 is the critical value of the reduced crystal field separating the ferrimagnetic region from the paramagnetic region at zero temperature, ends on a higher value of the reduced temperature and d on the second-order phase transition lines. The existence of the compensation temperature of this work shows disagreement with the results of Monte Carlo study [31], since where it was told that the system does not present any compensation temperature. It should also be mentioned that in [30] no discussion is given about the existence of the compensation temperature, as a result no comparison is possible with this work.…”

“…As we mentioned above the existence of a tricritical point for 4 q = [30] is in disagreement with this work and of [31]. The Monte Carlo calculations [31] are carried out only on a square lattice, i.e. 4 q = , and no triciritcal point is observed, which also means that the system does not yield a tricritical point for 3 q = , in agreement with this work.…”

“…We have obtained tricritical points for q = 5 and 6, which is in agreement with the results of [30], since the effective field calculations [30] yield a tricritical point for q = 4, even if the calculations are not carried out for higher coordination numbers, means that the system does exhibit tricritical points for 4 q ≥ , therefore agreeing with the result of this work about the existence of tricritical point. As we mentioned above the existence of a tricritical point for 4 q = [30] is in disagreement with this work and of [31]. The Monte Carlo calculations [31] are carried out only on a square lattice, i.e.…”

“…Since for a certain coordination numbers of the system, both second-and first-order phase transition lines exist, where they combine to each other is called the tricritical point indicated with a filled triangle and exist as seen in the figure when 5 q ≥ . As shown in the figure, the system does not present any tricritical points for q = 3 and q = 4, which should be compared with the results of the studies using an effective-field theory [30] and a Monte Carlo simulation [31]. In the first one of these two work [30], the calculations are done for q = 3 and 4 and the obtained results are depicted in their Fig.…”

Dependence on dilution of critical and compensation temperatures of a two-dimensional mixed spin-1/2 and spin-1 system

“…(1) does not play a role on the compensation temperature, whereas observation of the compensation temperature depends on the parameters J 4 and D. This point has been discussed in Refs. [13,14]. Therefore, in this study, we have particularly focused on the effect of the different dilution rates with non-magnetic atoms N for arbitrary fixed J 1 , J 4 and D. On the other hand, to analyze the effect of the non-magnetic atoms on the critical and compensation temperatures, for fixed J 1 ¼ À2, the second zero denotes the temperature value at which M is zero which corresponds to critical temperature point.…”