Resonant x-ray scattering from LaSr2Mn2O7 at the MnK edge -: art. no. 024414

We have investigated Mn K edge resonant scattering from a single crystal of the bilayered manganite LaSr2Mn2O7 in the charge/orbital ordered state (T= 170 K). A strong intensity enhancement of the tetragonal superlattice reflection ( -1/4, 1/4, 10) has been observed as the x-ray energy is tuned to the Mn K edge. In recent years a strong controversy arose regarding the nature of these kinds of superlattice reflections, i.e., whether their origin is due to Jahn-Teller distortion, orbital ordering, or both. We have thus performed realistic calculations to simulate the resonant signal, based on multiple-scattering theory and the finite difference method. We have found that Jahn-Teller distortion alone correctly describes the main features of the experimental data, the orbital ordering contribution being one order-of-magnitude smaller in amplitude.