PERCOLATION-LIKE TRANSITION IN DLA WITH 2 SPECIES

We introduce a DLA model with two species in order to simulate the gro wth of alternate clusters. We perform intensive numerical simulations in two dimensions in which the proportions of the two species are vari ed. A critical point, analogous to a percolation threshold, is found a nd a new class of critical exponents is obtained for this transition. Within numerical accuracy, the fractal dimension of the clusters is fo und to be the same as in the usual DLA model, independent of the speci es concentrations. Possible connections with the growth of two-dimensi onal ionic crystals are discussed.