Effects of a random crystal field on the spin-2 Blume-Capel model

“…Experimentally, the spins of Fe II ions are spin-2, and it is found that these ions have anisotropy (Mathonière et al , 1996). Theoretically, various magnetic properties of spin-2 BC systems have been studied by well-known methods in the equilibrium statistical physics such as the mean field approximation (Bahmad et al , 2007; Plascak and Moreira, 1993), the effective field theory with correlations (Ertaş et al , 2012; Jiang et al , 2000; Liang et al , 2004; Yigit and Albayrak, 2012), the Glauber-type stochastic dynamics (Temizer et al , 2016; Temizer and Korkmaz, 2012), the Monte Carlo simulation (Lara and Plascak, 1998; Iwashita et al , 2010), the exact recursion relations on the Bethe lattice (Erdinç et al , 2006), the four-spin model approximation (Iwashita et al , 2000) and the renormalization group method (Hachem et al , 2017; Yang and Xie, 2016).…”

Section: Introductionmentioning

confidence: 99%

The mixed spin-3/2 and spin-2 Blume-Capel model by renormalization group approach

Kihel

Saadi

Aharrouch

et al. 2021

MMMS

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PurposeThe authors investigate the magnetic properties of a mixed spin-3/2 and spin-2 Blume-Capel model on square and cubic lattices with two different single-ion anisotropies.Design/methodology/approachTo study the critical behavior of a mixed spin-3/2 and spin-2 system, the authors have used a real space renormalization group approximation and specifically the Migdal-Kadanoff technique. The authors give the phase diagrams for two different cases: (1) on the (Δ/|J|, 1/|J|) plane with ΔA = ΔB = Δ, and (2) on the (ΔA/|J|, 1/|J|) and (ΔB/|J|, 1/|J|) planes for selected values of ΔB/|J| and ΔA/|J|, respectively.FindingsThe phase diagrams obtained show that the system exhibits both second- and first-order phase transitions as well as tricritical points for some values of the anisotropies. Moreover, using the variation of the free energy and its derivative at low temperatures, the authors have seen the appearance of first-order transitions at very low temperatures.Originality/valueFew investigations of mixed spin-3/2 and spin-2 systems with crystal field have been realized. For this reason, the authors use the renormalization group approach to complete the work done on these systems. In absence of an exact solution, this contributes to the synthesis of the approximation results on mixed spins models.

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“…The exchange interaction parameter J is assumed to be positive. The first summation is carried out only over nearest pairs of spins and ∆ i is a quenched random crystal field distributed according to the probability distribution [22][23][24][25]:…”

Section: Model and Methodsmentioning

confidence: 99%

“…on the other hand, we have shown in some of our recent works [22,23] the existence of interesting properties in the magnetization behavior and phase diagrams in the presence of a random crystal-field.…”

Section: Introductionmentioning

confidence: 99%