PERPENDICULAR COUPLING AT FE-FEF2 INTERFACES

We have studied the exchange anisotropy of ferromagnetic Fe films grow n on antiferromagnetic FeF2 single crystals. The behavior of the hyste resis loops of the Fe above and below the Neel temperature T-N of FeF2 indicates a 90 degrees rotation of the ferromagnetic easy axis due to the antiferromagnetic ordering. By examining the Fe hysteresis loops together with the FeF2 susceptibility behavior we infer that below T-N the ferromagnetic and antiferromagnetic spins are coupled perpendicul ar to each other. This behavior can be explained by recent micromagnet ic calculations on exchange bias systems, or by magnetoelastic effects . (C) 1998 American Institute of Physics.