Electrical conduction in metal foils

Abstract

The most popular theory concerning the electrical resistivity of metal foils is that given by Fuchs, despite the presence of a physically more realistic theory developed by Soffer. It is shown that as a result of using Fuchs' theory experimentalists have been led to erroneous conclusions regarding both the surface-induced deviations from Mathiessen's rule (DMR) and the temperature dependence of the product of the bulk resistivity and the bulk electron mean free path rho _infinity lambda _infinity . It is shown that Soffer's theory may be well fitted to the available data on aluminium foils using a temperature-independent rho _infinity lambda _infinity whilst also satisfactorily explaining surface-produced DMR. Consequently surface scattering is shown to be better characterised by Scoffer's model, which involves an angle-dependent scattering parameter, than by Fuchs' model which assumes that surface scattering is independent of angle of incidence. The two theories are shown to be equivalent only when the sample thickness is greater than the bulk electron mean free path.