Dynamic behavior of driven interfaces in models with two absorbing states

We study the dynamics of an interface (active domain) between different abs orbing regions in models with two absorbing states in one dimension: probab ilistic cellular automata models and interacting monomer-dimer models. Thes e models exhibit a continuous transition from an active phase into an absor bing phase, which belongs to the directed Ising (DI) universality class. In the active phase, the interface spreads ballistically into the absorbing r egions and the interface width diverges linearly in time. Approaching the c ritical point, the spreading velocity of the interface vanishes algebraical ly with a DI critical exponent. Introducing a symmetry-breaking field h tha t prefers one absorbing state over the other drives the interface to move a symmetrically toward the unpreferred absorbing region. In Monte Carlo simul ations, we find that the spreading velocity of this driven interface shows a discontinuous jump at criticality. We explain that this unusual behavior is due to a finite relaxation time in the absorbing phase. The crossover be havior from the symmetric case (DI class) to the asymmetric case (directed percolation class) is also studied. We find the scaling dimension of the sy mmetry-breaking field y(h)=1.21(5). [S1063-651X(99)05805-5].