skip to main content

DOE PAGESDOE PAGES

Title: Valence-state reflectometry of complex oxide heterointerfaces

Emergent phenomena in transition-metal-oxide heterostructures such as interface superconductivity and magnetism have been attributed to electronic reconstruction, which, however, is difficult to detect and characterise. Here we overcome the associated difficulties to simultaneously address the electronic degrees of freedom and distinguish interface from bulk effects by implementing a novel approach to resonant X-ray reflectivity (RXR). Our RXR study of the chemical and valance profiles along the polar (001) direction of a LaCoO3 film on NdGaO3 reveals a pronounced valence-state reconstruction from Co3+ in the bulk to Co2+ at the surface, with an areal density close to 0.5 Co2+ ions per unit cell. An identical film capped with polar (001) LaAlO3 maintains the Co3+ valence over its entire thickness. As a result, we interpret this as evidence for electronic reconstruction in the uncapped film, involving the transfer of 0.5e per unit cell to the subsurface CoO2 layer at its LaO-terminated polar surface.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [5] ;  [10]
  1. IFW-Dresden, Dresden (Germany); Univ. of British Columbia, Vancouver, BC (Canada)
  2. Univ. of British Columbia, Vancouver, BC (Canada); Max Planck Institute for Solid State Research, Stuttgart (Germany)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sungkyunkwan Univ., Suwon (Korea)
  4. Canadian Light Sources, Inc., Saskatoon, SK (Canada)
  5. Univ. of British Columbia, Vancouver, BC (Canada)
  6. Univ. of British Columbia, Vancouver, BC (Canada); Max-Planck Institute for Chemical Physics of Solids, Dresden (Germany)
  7. Max-Planck Institute for Chemical Physics of Solids, Dresden (Germany)
  8. Univ. Wurzburg, Wurzburg (Germany)
  9. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  10. Univ. of British Columbia, Vancouver, BC (Canada); Univ. Wurzburg, Wurzburg (Germany)
Publication Date:
OSTI Identifier:
1329159
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
npj Quantum Materials
Additional Journal Information:
Journal Volume: 1; Journal ID: ISSN 2397-4648
Publisher:
Nature Publishing Group
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE electronic properties and materials; optical spectroscopy; surfaces; interfaces and thin films; two-dimensional materials