Multicritical Behavior in the Ising Model with Dipolar Interactions

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

Buenos Aires

Congreso; Fronteirs in Physical Sciences Humboldt Kolleg; 2016

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 the stripe-orderedwith 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?TLphase 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 the critical exponents is obtained, and in all the studied cases they depend on δbut do not belong to the Ising universality class. Furthermore, short-time dynamic studies reveal that at the point where the mentioned lines meet with the h1-h2 line, i.e.,at δ= 1.2585, the critical phase corresponding to the h1?TL transition coexists with the h2 phase.