Critical properties of the frustrated Ising model on a honeycomb lattice: A Monte Carlo study

Abstract

Critical and in the highly frustrated regime also dynamical properties of the J 1 − J 2 Ising model with competing nearest-neighbor J 1 and second-nearest-neighbor J 2 interactions on a honeycomb lattice are investigated by standard Monte Carlo and parallel tempering simulations. The phase boundary is determined as a function of the coupling ratio for the phase transition between the paramagnetic and ferromagnetic states within R ≡2 the transition remains second-order and complies with the standard Ising universality class. In the highly frustrated regime of R < −0.2 and low temperatures the system tends to freeze to metastable domain states, separated by large energy barriers, which show extremely sluggish dynamics. The resulting huge equilibration and autocorrelation times hinder the analysis of critical properties by using standard Monte Carlo techniques. The parallel tempering approach facilitates much better tunneling through the energy barriers, nevertheless, the convergence to the equilibrium remains beyond the reach even for relatively small system sizes and thus the character of the transition in this region remains to be determined.