Using an apparatus in which thin films can be deposited and then
immediately transferred without exposure to air into an adjoining
cryostat, we present results on the disorder-induced changes in
conductivity and magnetic behavior of thin-film ferromagnets. The
experiments are motivated by the question of how disorder, which is
known to localize spin-oriented carriers, affects magnetism in itinerant
(band) ferromagnets. For Fe films we find a weak-localization quantum
correction to the anomalous Hall effect, whereas in Gd films we
observe an additional localizing, linear in temperature quantum
correction to the conductivity due to scattering off spin waves.
At higher stages of disorder, evidence will be presented for two
distinct and rather surprising behaviors: for Gd films, a
scale-dependent conductivity that collapses onto separate curves on each
side of a metal-insulator transition, and for Fe and Co films, an
anomalous Hall insulator behavior that can be ascribed to granularity.
To begin viewing slides, click on the first slide below. (Or, view as pdf.)