Metastable states in a two-dimensional Ising model with dipolar interactions

The equilibrium phase diagram of a two-dimensional Ising model with competing exchange and dipolar interactions is analyzed using a Monte Carlo simulation technique. We consider the low temperature region of the (3, T) phase diagram (6 being the ratio between the strengths of the exchange and dipolar interactions) for the range of values of 8 where striped phases with widths h = 1 and 2 are present. We show that the transition line between both phases is a first order one. We also show that, associated with the first-order phase transition, there appear metastable states of the phase h = 2 in the region where the phase h = 1 is the thermodynamically stable one and vice versa. (C) 2002 Elsevier Science B.V. All rights reserved.