SPIN REVERSAL IN BILAYER ULTRATHIN MAGNETIC-FILMS

We discuss the micromagnetics of two coupled layers of ultrathin films . The spins change from a closure domain arrangement to mostly aligned as the interlayer spacing is decreased. There are remanent domains at the edges which serve as nucleation centers and control the switching behavior in a field. The domain patterns are often changed after a hy steresis cycle, consistent with recent measurement of the giant magnet oresistance in multilayer structures. Different vorticity of the edge domains can lead to very different zero-field remanent domain structur es.