title: Resonant scattering and multiple Bragg X-ray diffraction in LaMnO3; a classical view.
abstract: The mechanism for resonant scattering in LaMnO(3) has been the subject of some controversy between two models. Model (A) is based on orbital ordering, whereas model (B) invokes the Jahn-Teller distortion. From the structural point of view, the two models lead to different d-electron densities. The forbidden reflection 300 is turned on by resonance, leading to a well defined scheme for the lobes of the Mn d electrons [model (A)]. It turns out that the same experimental results could have been interpreted according to model (B). The only difference is that this alternative interpretation would have required a structure factor F(300) of opposite sign. This is a typical example of a phase problem. An experimental technique has been applied for phase determination based on multiple Bragg scattering. This shows that the multiple-beam results are in agreement with model (B), not with model (A), laying to rest a long overdue controversy.
authors.affiliation: Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036, USA. colella@physics.purdue.edu
authors.forename: Roberto
authors.initials: R
authors.lastname: Colella
authors.forename: Qun
authors.initials: Q
authors.lastname: Shen