Diffraction of X-rays by magnetic materials. II. Measurements on antiferromagnetic Fe₂O₃

Abstract

Two of the magnetic superlattice Bragg reflections of a single crystal of hematite (Fe2O3) have been measured by diffraction of X-rays produced from a conventional source, and compared to the intensities expected from the photon-spin scattering. Several orientations of the spins relative to the beams have been realized by rotating the crystal and by changing its temperature through the Morin (spin-flip) transition; in some of the measurements, the polarization produced by the monochromator was enhanced and this produced a visible asymmetry in the dependence of the intensities on the spin direction. The variations of the intensities during these changes of configuration are characteristic of magnetic scattering; the observed variations, as well as the absolute intensities, agree with the theory apart from some discrepancies. These may be due to intense multiple-scattering effects, and to some possible anomalies in the spin direction near the sample surface. As an application of this technique, changes of the direction of magnetization when a magnetic field is applied to the weakly ferromagnetic room-temperature phase have been investigated.