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arXiv · 1311.5160

Electron Correlation in Oxygen Vacancy in SrTiO$_3$

Chungwei Lin·Alexander A. Demkov
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Abstract

Oxygen vacancies are an important type of defect in transition metal oxides. In SrTiO$_3$ they are believed to be the main donors in an otherwise intrinsic crystal. At the same time, a relatively deep gap state associated with the vacancy is widely reported. To explain this inconsistency we investigate the effect of electron correlation in an oxygen vacancy (OV) in SrTiO$_3$. When taking correlation into account, we find that the OV-induced localized level can at most trap one electron, while the second electron occupies the conduction band. Our results offer a natural explanation of how the OV in SrTiO$_3$ can produce a deep in-gap level (about 1 eV below the conduction band bottom) in photoemission, and at the same time be an electron donor. Our analysis implies an OV in SrTiO$_3$ should be fundamentally regarded as a magnetic impurity, whose deep level is always partially occupied due to the strong Coulomb repulsion. An OV-based Anderson impurity model is derived, and its implications are discussed.

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Chungwei Lin, Alexander A. Demkov. 2013-11-20. Electron Correlation in Oxygen Vacancy in SrTiO$_3$. https://doi.org/10.1103/physrevlett.111.217601

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