APPROACHING THE NI PERCOLATION-THRESHOLD BY THIN-FILM IRRADIATION

We have reproduced a percolating structure in thin Ni films by an inho mogeneous sputtering process. The morphological disorder has been stud ied using TEM and 'in situ' transport measurements during ion irradiat ion. The fluence dependence of the resistance shows a singularity foll owing a 2D percolation law. The formation of the hole structure is con sistent with a Poisson mechanism. A computer simulation developed usin g a code based on a Poisson statistics allows us to account for the ex perimental values of the percolation threshold (p(c) = 0.37) and the o verall shape of the infinite cluster.