Observation of magnetic domains by neutron diffraction topography

Neutron diffraction topography is an observation technique in which Bragg reflection is used to produce images of single crystals. The magnetic interaction of neutrons with the material provides a unique possibility for observing magnetic domains of all kinds directly. The physical principle of this visualization and the limitations of the method are discussed. Work on the observation of ferromagnetic domains and, in antiferromagnets, of q (or T) and S domains in NiO, of 180° (or time-reversed) domains in MnF2, and of chirality domains in helimagnetic terbium is reviewed.