Reversal of the extraordinary Hall effect polarity in thin Co/Pd multilayers

TL;DR

This study investigates how the extraordinary Hall effect (EHE) polarity in Co/Pd multilayers can reverse due to surface scattering and aging, impacting their potential use in magnetic memory devices.

Contribution

It demonstrates the polarity reversal of EHE in thin Co/Pd multilayers caused by surface scattering and aging effects, revealing new insights into EHE behavior in these materials.

Findings

EHE polarity changes from negative to positive as multilayer thickness decreases.

Aging also causes EHE polarity reversal in thicker samples.

Surface scattering dominates EHE polarity in thin multilayers.

Abstract

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.