Electronic structure of Nd1−xYxMnO3 from Mn K edge absorption spectroscopy and DFT methods

• Reduction in the pre-edge intensity of Mn K edge spectrum with doping.
• DFT based LMTO calculations are consistent with experimental observations.
• Increase in the band gap and decrease in the magnetic moment as seen from experiments.
• Signature of orbital ordering seen in density of states of pure compound, not seen in doped compound.
• Greater hybridization and delocalization of the Mn 3d–Mn 4p orbitals.

The electronic structure of Nd1−xYxMnO3 (x=0–0.5) is studied using x-ray absorption near-edge structure (XANES) spectroscopy at the Mn K-edge along with the DFT-based LSDA+U and real space cluster calculations. The main edge of the spectra does not show any variation with doping. The pre-edge shows two distinct features which appear well-separated with doping. The intensity of the pre-edge decreases with doping. The theoretical XANES were calculated using real space multiple scattering methods which reproduces the entire experimental spectra at the main edge as well as the pre-edge. Density functional theory calculations are used to obtain the Mn 4p, Mn 3d and O 2p density of states. For x=0, the site-projected density of states at 1.7 eV above Fermi energy shows a singular peak of unoccupied eg (spin-up) states which is hybridized Mn 4p and O 2p states. For x=0.5, this feature develops at a higher energy and is highly delocalized and overlaps with the 3d spin-down states which changes the pre-edge intensity. The Mn 4p DOS for both compositions, show considerable difference between the individual px, py and pz states. For x=0.5, there is a considerable change in the 4p orbital polarization suggesting changes in the Jahn–Teller effect with doping.