Transport properties of metallic granular metal thin films

Granular metals (or "cermets"), consisting of small metal particles imbedded in an insulating matrix, are of interest from a basic scientific standpoint, as well as for their potential technological applications. In particular, they offer an opportunity to explore fundamental questions about the roles of disorder and finite particle size in electrical transport. Sputter deposited films are well-suited for such studies because of the range of particle sizes and metal volume fractions possible. As a result, materials can be prepared with electrical properties which vary continuously from those of weakly disordered metals to excellent insulators. Since electron localization effects depend strongly on system dimensionality, additional information can be obtained by varying film thickness. The results of a study of the electrical resistivity and magnetoresistance of a series of granular Ni films in the metallic regime are reported.