Issue 38, 2019

Strain analysis from M-edge resonant inelastic X-ray scattering of nickel oxide films

Abstract

Electronic structure modifications due to strain are an effective method for tailoring nano-scale functional materials. Demonstrated on nickel oxide (NiO) thin films, Resonant Inelastic X-ray Scattering (RIXS) at the transition-metal M2,3-edge is shown to be a powerful tool for measuring the electronic structure modification due to strain in the near-surface region. Analyses from the M2,3-edge RIXS in comparison with dedicated crystal field multiplet calculations show distortions in 40 nm NiO grown on a magnesium oxide (MgO) substrate (NiO/MgO) similar to those caused by surface relaxation of bulk NiO. The films of 20 and 10 nm NiO/MgO show slightly larger differences from bulk NiO. Quantitatively, the NiO/MgO samples all are distorted from perfect octahedral (Oh) symmetry with a tetragonal parameter Ds of about −0.1 eV, very close to the Ds distortion from octahedral (Oh) symmetry parameter of −0.11 eV obtained for the surface-near region from a bulk NiO crystal. Comparing the spectra of a 20 nm film of NiO grown on a 20 nm magnetite (Fe3O4) film on a MgO substrate (NiO/Fe3O4/MgO) with the calculated multiplet analyses, the distortion parameter Ds appears to be closer to zero, showing that the surface-near region of this templated film is less distorted from Oh symmetry than the surface-near region in bulk NiO. Finally, the potential of M2,3-edge RIXS for other investigations of strain on electronic structure is discussed.

Graphical abstract: Strain analysis from M-edge resonant inelastic X-ray scattering of nickel oxide films

Article information

Article type
Paper
Submitted
26 Jun 2019
Accepted
22 Aug 2019
First published
20 Sep 2019
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2019,21, 21596-21602

Strain analysis from M-edge resonant inelastic X-ray scattering of nickel oxide films

P. S. Miedema, N. Thielemann-Kühn, I. A. Calafell, C. Schüßler-Langeheine and M. Beye, Phys. Chem. Chem. Phys., 2019, 21, 21596 DOI: 10.1039/C9CP03593A

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