The impact of crystal symmetry on the electronic structure and functional properties of complex lanthanum chromium oxides

Liang Qiao, Haiyan Xiao, Steve M Heald, Mark E Bowden, Tamas Varga, Gregory J Exarhos, Mike Biegalski, Ilia N Ivanov, William J Weber, Timothy Droubay, Scott A Chambers

    Research output: Contribution to journalArticlepeer-review


    Complex oxides exhibit a wide range of crystal structures, chemical compositions and physical properties. The underlying drivers determining the complicated structure-composition-property phase diagrams are the relative positions and orbital overlaps between the metal cations and the oxygen anions. Here we report a combined experimental and theoretical investigation of the structure and bonding in a series of lanthanum chromium oxides prepared by reactive molecular beam epitaxy. Of particular interest is the charge state and local coordination of the Cr. We have stabilized LaCrO3, LaCrO4 and La2CrO6 films by controlling the three elemental fluxes during deposition, and have carried out x-ray diffraction, x-ray photoemission, and x-ray absorption spectroscopy, as well as first-principles calculations, to determine structure, charge state, chemical bonding, and electronic structure. Significant changes in bonding character and orbital interaction are revealed with decreasing ligand symmetry from octahedral to tetrahedral Cr coordination. Both LaCrO4 and La2CrO6 with tetrahedrally coordinated Cr show strong pre-edge features in the Cr K-edge near-edge structure whereas LaCrO3 with octahedrally coordinated Cr exhibits very weak pre-edge features. The origin of these pre-edge features is discussed based on various selection rules and ligand symmetry. We also demonstrate an increase in cation-anion orbital hybridization and a decrease in long-range ligand coupling induced by this symmetry reduction. These in turn result in dramatic modifications of the macroscopic optical and magnetic properties.
    Original languageEnglish
    JournalJournal of Materials Chemistry C
    Publication statusPublished - 2013


    Dive into the research topics of 'The impact of crystal symmetry on the electronic structure and functional properties of complex lanthanum chromium oxides'. Together they form a unique fingerprint.

    Cite this