Depth-dependent atomic valence determination by synchrotron techniques

Robbyn Trappen, Jinling Zhou, Vu Thanh Tra, Chih Yeh Huang, Shuai Dong, Ying-hao Chu, Mikel B. Holcomb*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The properties of many materials can be strongly affected by the atomic valence of the contained individual elements, which may vary at surfaces and other interfaces. These variations can have a critical impact on material performance in applications. A non-destructive method for the determination of layer-by-layer atomic valence as a function of material thickness is presented for La0.7Sr0.3MnO3 (LSMO) thin films. The method utilizes a combination of bulk- and surface-sensitive X-ray absorption spectroscopy (XAS) detection modes; here, the modes are fluorescence yield and surface-sensitive total electron yield. The weighted-average Mn atomic valence as measured from the two modes are simultaneously fitted using a model for the layer-by-layer variation of valence based on theoretical model Hamiltonian calculations. Using this model, the Mn valence profile in LSMO thin film is extracted and the valence within each layer is determined to within an uncertainty of a few percent. The approach presented here could be used to study the layer-dependent valence in other systems or extended to different properties of materials such as magnetism.

Original languageEnglish
Pages (from-to)1711-1718
Number of pages8
JournalJournal of Synchrotron Radiation
Volume25
Issue number6
DOIs
StatePublished - 1 Nov 2018

Keywords

  • Hamiltonian calculations
  • manganites
  • thin films
  • valence
  • X-ray absorption

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