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

Salafranca Laforga, Juan I; Salafranca, Juan; Biskup, Nevenko; Mehta, Virat; Oxley, Mark P; Suzuki, Yuri; Pennycook, Stephen J; Pantelides, Sokrates T.; Varela del Arco, Maria

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

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Abstract

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.

Authors:

Salafranca Laforga, Juan I ^[1]; Salafranca, Juan ^[2]; Biskup, Nevenko ^[1]; Mehta, Virat ^[3]; Oxley, Mark P ^[1]; Suzuki, Yuri ^[4]; Pennycook, Stephen J ^[5]; Pantelides, Sokrates T. ^[6]; Varela del Arco, Maria ^[1]

ORNL
Universidad Complutense de Madrid, Spain
University of California, Berkeley
Stanford University
University of Tennessee, Knoxville (UTK)
Vanderbilt University, Nashville

Publication Date:: Wed Jan 01 00:00:00 EST 2014

Research Org.:: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 1128995

DOE Contract Number:: DE-AC05-00OR22725

Resource Type:: Journal Article

Journal Name:: Physical Review Letters

Additional Journal Information:: Journal Volume: 112

Country of Publication:: United States

Language:: English

Citation Formats


                    Salafranca Laforga, Juan I, Salafranca, Juan, Biskup, Nevenko, Mehta, Virat, Oxley, Mark P, Suzuki, Yuri, Pennycook, Stephen J, Pantelides, Sokrates T., and Varela del Arco, Maria. Insulating ferromagnetic oxide films: the controlling role of oxygen vacancy ordering.  United States: N. p., 2014. 
        Web.

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                    Salafranca Laforga, Juan I, Salafranca, Juan, Biskup, Nevenko, Mehta, Virat, Oxley, Mark P, Suzuki, Yuri, Pennycook, Stephen J, Pantelides, Sokrates T., & Varela del Arco, Maria. Insulating ferromagnetic oxide films: the controlling role of oxygen vacancy ordering.  United States.

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                    Salafranca Laforga, Juan I, Salafranca, Juan, Biskup, Nevenko, Mehta, Virat, Oxley, Mark P, Suzuki, Yuri, Pennycook, Stephen J, Pantelides, Sokrates T., and Varela del Arco, Maria. 2014.  
        "Insulating ferromagnetic oxide films: the controlling role of oxygen vacancy ordering".  United States.

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@article{osti_1128995,

  title        = {Insulating ferromagnetic oxide films: the controlling role of oxygen vacancy ordering},

  author       = {Salafranca Laforga, Juan I and Salafranca, Juan and Biskup, Nevenko and Mehta, Virat and Oxley, Mark P and Suzuki, Yuri and Pennycook, Stephen J and Pantelides, Sokrates T. and Varela del Arco, Maria},

  abstractNote = {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.},

  doi          = {},

  url          = {https://www.osti.gov/biblio/1128995},
  journal      = {Physical Review Letters},
number       = ,

  volume       = 112,

  place        = {United States},

  year         = {Wed Jan 01 00:00:00 EST 2014},

  month        = {Wed Jan 01 00:00:00 EST 2014}

}

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