Incomplete AFM interface moment flipping in AFM/FM bilayers

Summary form only given. In antiferromagnet/ferromagnet (AFM/FM) bilayer systems, the induced unidirectional anisotropy of the ferromagnetic layer comes from the net moment of the AFM at the interface. It is commonly assumed that the net AFM interface moment from all AFM grains is aligned parallel to the annealing field direction. However, our model shows that this may not be the case for PtMn/CoFe bilayers. At an annealing temperature T/sub anneal/, the AFM grains that have energy barriers larger than the threshold value of k/sub B/T/sub anneal//spl times/ln(f/sub 0//spl times/t/sub anneal/) cannot flip their interface moment to reach the global energy minimum during the annealing process and therefore still have random interface moment f/sub 0/(=10/sup 9/ Hz) is the attempt rate and t/sub anneal/ is the annealing time.