  Thin Co/Pd multilayers, with room temperature perpendicular anisotropy and an
enhanced surface scattering, were studied for the possible use in the
extraordinary Hall effect (EHE) - based magnetic memory devices. Polarity of
the EHE signal was found to change from negative in thick samples to positive
in thin ones. Reversal of EHE sign was also observed in thick samples with
aging. The effect is argued to be related to the dominance of surface
scattering having the EHE polarity opposite to that of the bulk.
