Real-time magneto-optical indicator film images reveal distinct asymmetry in 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 antiferromagnetic layer. Magnetization reversal from the ground state begins at the thick end of the wedge where the exchange anisotropy field (HE) is minimal and the magnetostatic field (HMS) is maximal, whereas reversal into the ground state begins from the thin end where HE is maximal and HMS is minimal.

Macroscopic domain structures have been realized in wedged-permalloy (Py)/uniform-FeMn bilayers during magnetization reversal. When the exchange anisotropy is established perpendicular or parallel to the wedge direction, two macroscopic domains are observed. Separating these domains are a 180° wall in the perpendicular geometry and an intermediate band containing large density of stripe-type microdomains in the parallel geometry. While the exchange field remains practically the same in both geometries, the coercivity and squareness of the loop are much less in the parallel geometry.