Antiferromagnetic Structure and Domains in Single Crystal NiO

Abstract

Single crystals of NiO have been annealed and stressed at room temperature to sweep out twin boundaries. Neutron diffraction and rotational torque studies have been made on a crystal which had only 1.3% of the twin orientation. The ferromagnetic sheet structure originally proposed in which the atomic moments lie in (111) planes is found to be correct. The anisotropy in the (111) plane is extremely small and at low fields the spins in the ferromagnetic sheet are locked in domains and the susceptibility is nearly isotropic. Rotation of the spins in (111) takes place at fields above 2400 oe.