Determination of the lowest unoccupied orbital in the layered perovskite LaSrMnO4 using polarized oxygen K edge absorption spectroscopy

Using polarized oxygen It edge spectroscopy, the first unoccupied orbital o f LaSrMnO4 was investigated. The lowest unoccupied orbital is of minority s pin d(xz), d(yz) character instead of the majority spin d(x2-y2) character. The d(x2-y2) orbital would be expected based on Hund's rule and the strong exchange interaction of the one-electron addition d(5) system. The explana tion is a strong ligand field splitting caused by the strong local site dis tortion of the Mn site which raises the energy of the majority spin d(x2-y2 ) orbital and lowers the energy of the d(xz), d(yz) orbitals. At the same t ime the two-electron integrals, which are responsible for the exchange inte raction, are screened because of covalency.