  We have explored the possibility to orient spins in antiferromagnetic thin
films with low magnetocrystalline anisotropy via the exchange coupling to
adjacent antiferromagnetic films with high magnetocrystalline anisotropy. We
have used MnO as a prototype for a system with negligible single-ion
anisotropy. We were able to control its spin direction very effectively by
growing it as a film on antiferromagnetic CoO films with different
predetermined spin orientations. This result may pave the way for tailoring
antiferromagnets with low magnetocrystalline anistropy for applications in
exchange bias systems. Very detailed information concerning the exchange
coupling and strain effects was obtained from the Mn $L_{2,3}$ soft x-ray
absorption spectroscopy.
