The Antiferromagnetic Domain Structure of Epitaxial Nickel Oxide

Epitaxially grown nickel oxide single crystals (thickness 10 to 200 mu m) have been examined below the Neel temperature (523 degrees K) by optical and X-ray diffraction topographic techniques. The antiferromagnetic domain structure in the as-grown crystals is extremely complex and sensitive to crystal thickness. Annealing simplifies the domain structure, but the presence of the magnesium oxide substrate is shown to inhibit the formation of the large domains observed in well-annealed Verneuil-grown crystals. The misorientation between adjacent domains has been measured by a direct technique and shown to be consistent with the theoretical value.