Crossover, locking-in, and intermittency of droplet growth rates in phase separation

Nonuniversal behavior in the dynamics of phase separation is discussed. An equation which exhibits a nonuniversal growth rate in a long-time limit is derived relying on the dynamic-scaling assumption. Two contradictory behaviors, a crossover to larger growth rate and a formation of a locked-in structure, are shown to be described by this equation in two limiting cases. The intermittent region lies between regions with these two contradictory behaviors. Two types of intermittent-growth-rate exponents are obtained. One, aI1, is valid at high temperatures, while the other, aI2, is valid at low temperatures. These two exponents are, respectively, aI1=w₁a₁+w₂a₂, and aI2=(w₁a₁+w₂a₂)^-1. Here wᵢ (i=1,2) are the probabilities of finding configuration associated, respectively, with the growth rates R∝t^a₁ and R∝t^a₂. a₁ is the largest exponent due to the curvature-driven force and a₂ is the next largest exponent; a₂=0 at zero temperature. Thus, for certain values of system parameters, the intermittent exponent aI varies from 0 to aI1 as the temperature is increased. Several aspects of the growth rates in parameter space are predicted. They are consistent with numerical simulations and fluid mixtures.