Consequences of Spin-Flop Coupling in Exchange Biased Films

Using a microscopic Heisenberg model which includes magnetostatic interactions, the Landau-Lifshitz-Gilbert equation of motion is solved in order to study several magnetic properties of ferromagnetic/antiferromagnetic bilayers. For perfectly flat interfaces, it is shown that spin-flop coupling does not lead to exchange bias as has been proposed, but rather gives rise to a uniaxial anisotropy which in turn causes the large coercivities observed in exchange biased films. The introduction of interfacial defects leads to exchange bias of the correct order of magnitude. copyright 1998 The American Physical Society