Resonant X-ray diffraction: multipole interpretation.
Résumé
A review. The aim of this work is to provide a crit. review of the multipole interpretation of resonant x-ray diffraction. After a brief historical introduction, we focus on the general formalism of electromagnetic multipole expansion in condensed matter. We then introduce the anomalous scattering amplitude from perturbation theory in the low-energy limit of the Dirac Hamiltonian. Finally, we merge the two previous sections by showing how the anomalous scattering amplitude can be interpreted in terms of elec. and magnetic multipoles. Some examples are then discussed, concerning the elec. quadrupole in manganites, "exotic" polar and axial toroidal multipoles in transition-metal oxides and polarization anal. allowing the disentanglement of nearby-lying multipoles in the energy spectrum. [on SciFinder(R)]