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

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

Physical Review E

American Physical Society

Año: 2016 vol. 94

2470-0045

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 δ. The obtained results indicate that the h1-TL phase transition line is continuous up to δ=1.2585, while for the h2-TL line a weak first-order character is found in the interval 1.2585≤δ≤1.36 and becomes continuous for 1.37≤δ≤1.9. This result suggests the existence of a tricritical point close to δ=1.37. When it is appropriate, the complete set of critical exponents is obtained, and in all the studied cases they depend on δ 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 δ=1.2585, the critical phase corresponding to the h1-TL transition coexists with the h2 phase.