Electrical Resistivity of Some Gold Alloys: A Search for Effects Due to Local Modes

If phonon-assisted electron scattering by impurities contributes appreciably to the electrical resistivity of alloys, localized modes about light impurities should lead to a resistance which increases faster than linearly at temperatures around $\frac{{\theta }_0}{2}$ where ${\theta }_0$ is the characteristic temperature of the local mode. The electrical resistivity of gold alloys containing 1.8 at.% Zn, 2.4 at.% Al and 2.6 at.% Cu was measured between 80 and 500°K. In these cases local modes are expected. Measurements were also made of alloys with 1.0 and 1.6 at.% Pt, where local modes should be absent. Substantial deviations from Matthiessen's rule were found, but not the temperature variation expected from local modes. It is suggested that this effect is obscured by deviations from Matthiessen's rule arising from the zone structure of gold. An unexplained discrepancy was found in the resistance of the 1.6% Pt alloy. The resistivity of pure gold between 80 and 480°K is tabulated in 20° steps.