Localization and electron-electron interaction effects in thin Au-Pd films and wires

Abstract

We have conducted extensive measurements of the low-temperature magnetoresistance of thin Au-Pd films and very-small-diameter Au-Pd wires. These results have been used to determine the importance of localization and electron-electron interaction effects in these systems. The magnetoresistance in the small magnetic fields employed in this work (<10 kG) appears to be due predominantly to localization. However, both localization and interactions contribute to the variation of the resistance with temperature in zero field, with interactions generally being dominant. From the measurements as a function of magnetic field, we have determined the inelastic scattering time, ${\tau }_i$, the magnetic impurity scattering time, ${\tau }_s$, and have placed an upper limit on the spin-orbit scattering time, ${\tau }_{\mathrm{so}}$. We find that ${\tau }_s$ is essentially the same for the films and wires, as expected since this is predicted to be a material (i.e., bulk) property which should be independent of dimensionality. The upper limits on ${\tau }_{\mathrm{so}}$ in one and two dimensions are also consistent. In contrast ${\tau }_i$ depends on the dimensionality of the sample, and has distinctly different temperature dependences in the two cases. In the films it appears to be due to electron-electron scattering in the presence of disorder in the two-dimensional limit, while in the wires it is due to the one-dimensional version of this scattering mechanism.