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Title: Insulating ferromagnetic oxide films: the controlling role of oxygen vacancy ordering

The origin of ferromagnetism in strained epitaxial LaCoO3 films has been a long-standing mystery. Here, we combine atomically resolved Z-contrast imaging, electron-energy-loss spectroscopy, and density-functional calculations to demonstrate that, in epitaxial LaCoO3 films, oxygen-vacancy superstructures release strain, control the film s electronic properties, and produce the observed ferromagnetism via the excess electrons in the Co d states. Although oxygen vacancies typically dope a material n-type, we find that ordered vacancies induce Peierls-like minigaps which, combined with strain relaxation, trigger a nonlinear rupture of the energy bands, resulting in insulating behavior.
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [4] ;  [5] ;  [6] ;  [1]
  1. ORNL
  2. Universidad Complutense de Madrid, Spain
  3. University of California, Berkeley
  4. Stanford University
  5. University of Tennessee, Knoxville (UTK)
  6. Vanderbilt University, Nashville
Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 112
Research Org:
Oak Ridge National Laboratory (ORNL)
Sponsoring Org:
SC USDOE - Office of Science (SC)
Country of Publication:
United States