Phase transitions and multicritical behavior in the Ising model with dipolar interactions

M. A. BAB; C. M. HOROWITZ; M. L. RUBIO PUZZO; G. P. SARACCO

PHYSICAL REVIEW E

AMER PHYSICAL SOC

Lugar: New York; Año: 2016 vol. 94 p. 421041 - 421048

1539-3755

In this work, the phase diagram of the ferromagnetic Ising model with dipole interactions is revisited with the aim of determining the nature of the phase transition between stripe-ordered phases with width n (hn ) and tetragonal liquid (TL) phases. Extensive Monte Carlo simulations are performed in order to study the short-time dynamic behavior of the observables for selected values of the ratio between the ferromagnetic exchange and dipolar constants $delta$. The obtained results indicate that the h1-TL phase transition line is continuous up to $delta = 1.2585$, while for the h2 -TL line a weak first-order character is found in the interval $1.2585leq delta leq 1.36$ and becomes continuous for $1.37leq delta leq 1.9$. This result suggests the existence of a tricritical point close to $delta = 1.37$.When it is appropriate, the complete set of critical exponents is obtained, and in all the studied cases they depend on $delta$ but do not belong to the Ising universality class. Furthermore, short-time dynamic studies reveal that at the point where the mentioned lines meet the h1-h2 line, i.e., at $delta = 1.2585$, the critical phase corresponding to the h1 -TL transition coexists with the h2 phase.