arXiv:1612.05841 · Physical Review E
Time-dependent Monte Carlo simulations of critical and Lifshitz points of the axial-next-nearest-neighbor Ising model
Roberto da Silva, Nelson A. Alves, J. R. Drugowich de Felício
Abstract
In this work, we study the critical behavior of second-order points, specifically the Lifshitz point (LP) of a three-dimensional Ising model with axial competing interactions [the axial-next-nearest-neighbor Ising (ANNNI) model], using time-dependent Monte Carlo simulations. We use a recently developed technique that helps us localize the critical temperature corresponding to the best power law for magnetization decay over time: ${\ensuremath{\langle}M\ensuremath{\rangle}}_{{m}_{0}=1}\ensuremath{\sim}{t}^{\ensuremath{-}\ensuremath{\beta}/\ensuremath{\nu}z}$, which is expected of simulations starting from initially ordered states. We obtain original results for the dynamic critical exponent $z$, evaluated from the behavior of the ratio ${F}_{2}(t)={\ensuremath{\langle}{M}^{2}\ensuremath{\rangle}}_{{m}_{0}=0}/{\ensuremath{\langle}M\ensuremath{\rangle}}_{{m}_{0}=1}^{2}\ensuremath{\sim}{t}^{3/z}$, along the critical line up to the LP. We explore all the critical exponents of the LP in detail, including the dynamic critical exponent $\ensuremath{\theta}$ that characterizes the initial slip of magnetization and the global persistence exponent ${\ensuremath{\theta}}_{g}$ associated with the probability $P(t)$ that magnetization keeps its signal up to time $t$. Our estimates for the dynamic critical exponents at the Lifshitz point are $z=2.34(2)$ and ${\ensuremath{\theta}}_{g}=0.336(4)$, values that are very different from those of the three-dimensional Ising model (the ANNNI model without the next-nearest-neighbor interactions at the $z$ axis, i.e., ${J}_{2}=0$), i.e., $z\ensuremath{\approx}2.07$ and ${\ensuremath{\theta}}_{g}\ensuremath{\approx}0.38$. We also present estimates for the static critical exponents $\ensuremath{\beta}$ and $\ensuremath{\nu}$, obtained from extended time-dependent scaling relations. Our results for static exponents are in good agreement with previous works.