Work

Chiral properties of hematite α -Fe 2 O 3 inferred from resonant Bragg diffraction using circularly polarized x rays

Year: 2013

Type: article

Abstract: Chiral properties of the two phases---collinear motif (below Morin transition temperature, ${T}_{M}\ensuremath{\approx}250$ K) and canted motif (above ${T}_{M}$)---of magnetically ordered hematite ($\ensuremath{\alpha}$-Fe${}_{2}$O${}_{3}$) have been identified in single-crystal resonant x-ray Bragg diffraction using circular polarized incident x rays tuned near the iron $K$ edge. Magnetoelectric multipoles, including an anapole, fully characterize the high-temperature canted phase, whereas the low-temperature collinear phase supports both parity-odd and parity-even multipoles that are time odd. Orbital angular momentum accompanies the collinear motif, whereas it is conspicuously absent with the canted motif. Intensities have been successfully confronted with analytic expressions derived from an atomic model fully compliant with chemical and magnetic structures. Values of Fe atomic multipoles previously derived from independent experimental data are shown to be completely trustworthy.

Source: Physical Review B

DOI: 10.1103/physrevb.88.094437