Resonant scattering and multiple Bragg X-ray diffraction in LaMnO3; a classical view

• Published in: Acta crystallographica. Section A, Foundations of crystallography Vol. 62; no. 6; pp. 459 - 462
• Main Authors: Colella, Roberto, Shen, Qun
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England Blackwell Publishing Ltd 01.11.2006; Blackwell; Wiley Subscription Services, Inc
• Subjects: Comparative studies; Condensed matter: structure, mechanical and thermal properties; Crystalline state (including molecular motions in solids); Crystallography; Diffraction; Exact sciences and technology; LaMnO3; multiple Bragg X-ray diffraction; Physics; resonant scattering; Scattering; Structure of solids and liquids; crystallography; Theory of crystal structure, crystal symmetry; calculations and modeling; X-ray diffraction; X-rays; Lanthanum oxides; Inorganic compounds; Structure factors; Bragg diffraction; Transition element compounds; Theoretical study; Distortion; XRD; Multiple scattering; Rare earth compounds; Resonance scattering; Manganese oxides; Experimental result; Ordering; Electron density
• ISSN: 0108-7673; 1600-5724; 2053-2733
• DOI: 10.1107/S010876730603889X

The mechanism for resonant scattering in LaMnO3 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 F300 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.