Coercivity induced by random field at ferromagnetic and antiferromagnetic interfaces

In the presence of random fields at an interface between a ferromagnetic an d an antiferromagnetic layer, the domain walls in the ferromagnetic layer a re pinned by local minimum energy. To move the domain walls, an applied mag netic field must be large enough to overcome statistically fluctuating ener gy. We have calculated this energy and found that the coercivity can be as large as a few kOe for a thin ferromagnetic layer. It is also found that th e coercive held at low temperature scales as 1/t(3/2) where t is the F laye r thickness, and the coercive field decreases strongly with temperature. (C ) 1999 Elsevier Science B.V. All rights reserved.