Localization and electron-interaction effects in a two-dimensional metal with strong spin-orbit scattering: Pd films

We observe positive, anisotropic, strongly-temperature-dependent magnetoresistance in ultrathin [(6-55)-{}] Pd films. Interpreted in the light of recent theory, we find that localization effects dominate, but that electron-interaction effects are present as well. A strong spin-orbit scattering (symplectic limit) causes the localization-induced magnetoresistance to be positive. The inelastic scattering rate varies as T², although its magnitude is considerably larger than expected for electron-electron scattering. In some films we find a low-temperature drooping of the magnetoresistance which cannot be explained in the conventional localization---plus---electron-interaction theory.