Polarization-dependent nickel 2p x-ray-absorption spectra of La{sub 2}NiO{sub 4+{delta}}

Journal Article · Thu Jan 01 04:00:00 EST 1998 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.57.1552· OSTI ID:567059

Kuiper, P ^[1]; van Elp, J ^[2]; Rice, D E; Buttrey, D J ^[3]; Lin, H; Chen, C T ^[4]

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1. Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden)
2. ISA, Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)
3. Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716 (United States)
4. ATT Bell Laboratories, Murray Hill, New Jersey 07974 (United States)

We present polarization dependent x-ray-absorption spectra at nickel L edges of well-characterized La{sub 2}NiO{sub 4+{delta}} single crystals. In the stoichiometric compound the splitting between the x{sup 2}{minus}y{sup 2} and the 3z{sup 2}{minus}r{sup 2} orbitals is 0.7 eV, according to a fit of the 2p{sup 5}3d{sup 9} multiplet to the spectra. This value is in agreement with an assignment of dd excitations of the optical spectrum. The Ni L edges of the doped compound are consistent with the isotropic prepeak observed at the oxygen 1s edge. Theory does not predict holes on the apex oxygens, but we argue that doping causes a polaronic deformation which reduces the tetragonal distortion of the NiO{sub 6} octahedra, and delocalizes the hole over all six ligands. {copyright} {ital 1998} {ital The American Physical Society}

• OSTI ID: 567059
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 3 Vol. 57; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
ABSORPTION SPECTRA
L SHELL
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
LIGANDS
MONOCRYSTALS
MULTIPLETS
NICKEL OXIDES
POLARONS
STOICHIOMETRY
X-RAY SPECTROSCOPY