Produção Nacional
Revisado por pares
The spin-3/2 Blume–Capel model with competing short- and long-range interactions
2016; Elsevier BV; Volume: 464; Linguagem: Inglês
10.1016/j.physa.2016.07.057
ISSN1873-2119
AutoresOctavio D. Rodrı́guez Salmon, José Ricardo de Sousa, Minos A. Neto, Igor T. Padilha, J. Roberto Viana Azevedo, Francisco Dinóla Neto,
Tópico(s)Complex Systems and Time Series Analysis
ResumoThe phase diagrams of the spin-3/2 Blume–Capel model with competing short and long-range interactions were studied through the free energy density obtained by analytical methods. The competition emerges when positive short-range interactions of strength K arranged in a linear chain tend to establish an anti-parallel spin order, whereas negative long-range interactions −J tend to align them in parallel. Thus, no ferromagnetic order exists for K/J>0.25. So, the phase-diagrams were scanned by varying the values of K, for 0<K/J<0.25. As in other similar study done for the spin-1 case, the second-order frontier separating the ferromagnetic and the paramagnetic phases is transformed gradually into a first-order line when K/J is greater than a certain critical value. Accordingly, there is a sub interval of K, for which two tricritical points appear restricting the length of the second-order frontier. Nevertheless, for greater values of K/J, the ferromagnetic–paramagnetic frontier becomes wholly of first order. Also, the typical line of coexistence of the spin-3/2 Blume–Capel model, which divides two different ferromagnetic phases of magnetization m=3/2 and m=1/2, becomes more complex by giving rise to another first-order line with a reentrant behavior that encloses a third ordered phase. In this case, the competition is such that there is a region in the phase diagram, where for each spin i with Si=3/2 (Si=−3/2), there is another spin j, where j=i+1 and Sj=1/2 (Sj=−1/2), such that the absolute value of the magnetization per spin is one.
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