Asymmetry in elementary events of magnetization reversal in a ferromagnetic/antiferromagnetic bilayer

Real-time magneto-optical indicator film images reveal distinct asymmetry i n the motion of a single domain wall in a wedged-NiFe/uniform-FeMn bilayer due to the nucleation and behavior of an exchange spring in the antiferroma gnetic layer Magnetization reversal from the round stare begins at the thic k. end of the wedge where the exchange anisotropy field (H-E) is minimal an d the magnetostatic field (H-MS) is maximal, whereas reversal into the grou nd state begins from the thin end where H-E is maximal and H-MS is minimal.