Investigation of local symmetry effects on the electronic structure of manganites: Hexagonal YMnO3 versus orthorhombic LaMnO3

Abstract

The local site symmetry effects on electronic structure of manganites were investigated by using theoretical analyses in terms of the cluster model calculations for the O K- and Mn L-2,L-3-edge x-ray-absorption spectroscopy (XAS) results of hexagonal YMnO3 and orthorhombic LaMnO3. YMnO3, which has an unusual MnO5 (D-3h) site symmetry, exhibits remarkably different electronic structure and XAS line shape from those of LaMnO3 with the conventional MnO6 (D-4h) site symmetry, despite the same Mn3+ (3d(4)) trivalent ionic state. We developed an algebraic formalism, which takes into account the crystal-field energies and hybridization strengths of the D-3h Mn 3d orbital in YMnO3. The deduced values are very consistent with the first-principles local-density approximation plus Hubbard U calculation results. The cluster model calculations involving the different site symmetries well reproduce the O K-edge and Mn L-2,L-3-edge spectra of both manganites. In the analyses of the O K-edge spectra, we also took into account the Y 4d and La 4f/5d orbital states.