  We report direct observation of charge accumulation effect on magnetization
reversal in a Pt/Co(0.5 nm)/Pt(0.5 nm)/Al2O3 structure with perpendicular
anisotropy. By imaging magnetic domain with polar Kerr microscopy, we evidence
that positive charges accumulating at the Pt/Al2O3 interface result in favoring
magnetic domain wall propagation, while negative charges hinder domain wall
nucleation and propagation. Our results suggest that magnetic properties in Co
layer can be strongly influenced by 5d electron accumulation/depletion in an
ultrathin Pt layer.
