Coercive mechanisms in ferromagnetic-antiferromagnetic bilayers

The magnetization reversal of polycrystalline ferromagnetic-antiferromagnetic bilayers is investigated by employing the Landau-Lifshitz-Gilbert equation. The magnetic interaction at the interface is modeled by a random field. It is found that the random field breaks the ferromagnetic layer into domains during magnetization reversal. The domain size is usually much smaller than that without the underlying antiferromagnetic layers. We quantitatively determine the enhanced coercivity as a function of the thickness of the ferromagnetic layer, the grain size, and the interface random field.