2-DIMENSIONAL WEAK LOCALIZATION IN COMBINED PERPENDICULAR AND PARALLEL MAGNETIC-FIELDS

We have studied the magnetoresistance of thin films of Au, Ag, and Au(Fe) (Au doped with small concentrations of Fe) at low temperatures. Magnetic fields both perpendicular and parallel to the plane of the film were employed, and in some experiments these two fields were applied simultaneously and independently. Our results are compared in detail with the predictions of weak-localization theory. The agreement between theory and experiment for purely perpendicular fields is reasonably good, but some of the behavior in parallel fields, especially for Au(Fe), cannot be reconciled with the usual theory. Our results can be qualitatively understood if one assumes that the spin-orbit-scattering length is field dependent, or that the phase-breaking length becomes shorter in large parallel fields. Either of these results would be contrary to conventional beliefs.