  We present magnetoresistance measurements performed on ultrathin films of
amorphous Ni and Fe. In these films the Curie temperature drops to zero at
small thickness, making it possible to study the effect of ferromagnetism on
localization. We find that non-ferromagnetic films are characterized by
positive magnetoresistance. This is interpreted as resulting from weak
antilocalization due to strong Bychkov-Rashba spin orbit scattering. As the
films become ferromagnetic the magnetoresistance changes sign and becomes
negative. We analyze our data to identify the individual contributions of weak
localization, weak antilocalization and anisotropic magnetoresistance and
conclude that the magnetic order suppresses the influence of spin-orbit effects
on localization phenomena in agreement with theoretical predictions.
