Mechanism of resonant X-ray scattering to observe the orbital ordering

Abstract Resonant X-ray scattering (RXS) has been developed as a powerful technique to observe the orbital ordering in correlated electron systems. However, the scattering mechanism has been controversial, especially in K -absorption edge resonance of transition metal oxides. We have made it clear by measuring the interference terms between the resonant scattering term and the Thomson scattering term, or between the resonant terms of dipolar ( E 1) and quadrupolar ( E 2) transition processes. The results indicate that the Jahn–Teller mechanism is more responsible than the Coulomb mechanism in an e g electron system (La 0.5 Sr 0.5 MnO 3 thin films) of 3d transition metal oxide, but it is the opposite way in a t 2g electron system (YTiO 3 ) of 3d transition metal oxides and a 4f electron system (DyB 2 C 2 ).