EFFECT OF QUENCHED DISORDER ON MOVING INTERFACES IN 2 DIMENSIONS

We consider the morphology and dynamics of an interface driven through a random two-dimensional medium by an applied force f. The onset of m otion is a critical phenomenon, with mean velocity upsilon approximate ly (f - f(c))zeta above the threshold force f(c). Fluctuations in the velocity exhibit a power law noise spectrum. At large length scales th e moving interfaces are self-affine with roughness exponent alpha = 0. 5. There is a crossover to different scaling behavior below the correl ation length, xi approximately (f - f(c))-nu. The type of scaling at s mall lengths depends upon the nature and strength of the disorder. Two examples are considered - a magnetic domain wall model exhibiting sel f-similar structure characteristic of percolation, and a fluid invasio n model which produces self-affine scaling.