%0 Journal Article
%A Biskup Zaja, Nevenko
%A Salafranca, Juan
%A Mehta, Virat
%A Oxley, Marrk P.
%A Suzuki, Yuri
%A Pennycook, Stephen J.
%A Pantelides, Sokrates T.
%A Varela Del Arco, María
%T Insulating ferromagnetic LaCoO_(3−δ) films: a phase induced  by ordering of oxygen vacancies
%D 2014
%@ 0031-9007
%U https://hdl.handle.net/20.500.14352/91493
%X The origin of ferromagnetism in strained epitaxial LaCoO_(3) 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 LaCoO_(3) 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.
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