Polar magnetization unveiled by polarized neutron diffraction

Polar magnetism is present when ions occupy sites that are not centres of inversion symmetry. Fortunately, such magnetization contributes to neutron scattering that is the bedrock of magnetic structure determinations. Experiments in which the scattered neutron polarization is analysed are not a novelty. Simulations of polarized neutron scattering amplitudes for room temperature haematite (alpha-Fe2O3) demonstrate the wealth of information on offer. Two magnetic motifs distinguished by the orientation of their bulk ferromagnetism are considered. Additionally, the symmetry-inspired simulations challenge a recent claim to have determined the absolute direction of the Dzyaloshinskii-Moriya (D-M) interaction.