Effects of agglomeration and magnetic boundary scattering on the electrical resistivity of nickel films

Abstract

The electrical resistivity of vacuum-evaporated nickel films has been studied as a function of thickness (166–3432 Å) and temperature (30–150 °C). The measurements have been performed in situ using the four-probe technique. The thicknesses of the films have been measured by a multiple-beam interferometer. The electrical resistivity ρ of a ferromagnetic metal film can be expressed as ρtotal=ρid+ργ+ρt +ρmω, where ρid, ργ, ρt, and ρmω are, respectively, the lattice, residual, surface, and magnetic wall resistivities. The thin films of nickel are known to have agglomerated structure below 400 Å and because of its ferromagnetic nature the magnetic domains should also play a role in its electrical properties. By studying the effects of change of resistivity with temperature on films of different thicknesses the role of the factors mentioned above has been identified. It has been concluded that to obtain nickel films of reproducible electrical properties, the deposition has to be done above the Curie temperature or the deposited film has to be annealed above the Curie temperature.