Resonant x-ray diffraction near the ironKedge in hematite (α-Fe2O3)

Abstract

An unexpected resonant enhancement in x-ray diffraction occurs at a forbidden reflection in the antiferromagnetic hematite. This fifty-fold increase in the diffracted signal, 10 eV below the iron K edge, exhibits a rotation in the x-ray polarization and a 60° azimuthal symmetry as the crystal is rotated about the reflection vector. The effect is explained to result from electronic quadrupole transitions in the anomalous scattering from iron and demonstrates that diffraction can be a sensitive probe of the electronic environment at specific atomic sites in the crystal.