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Open AccessArticle

Electronic Structure of Oxygen-Deficient SrTiO3 and Sr2TiO4

Peter Grünberg Institut (PGI-1) and Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich and JARA, 52428 Jülich, Germany
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Crystals 2019, 9(11), 580; https://doi.org/10.3390/cryst9110580
Received: 18 October 2019 / Revised: 31 October 2019 / Accepted: 1 November 2019 / Published: 7 November 2019
(This article belongs to the Special Issue Electronic Phenomena of Transition Metal Oxides)
The conductive behavior of the perovskite SrTiO 3 is strongly influenced by the presence of oxygen vacancies in this material, therefore the identification of such defects with spectroscopic methods is of high importance. We use density functional theory to characterize the defect-induced states in SrTiO 3 and Sr 2 TiO 4 . Their signatures at the surface, the visibility for scanning tunneling spectroscopy and locally conductive atomic force microscopy, and the core-level shifts observed on Ti atoms in the vicinity of the defect are studied. In particular, we find that the exact location of the defect state (e.g., in SrO or TiO 2 planes relative to the surface) are decisive for their visibility for scanning-probe methods. Moreover, the usual distinction between Ti 3 + and Ti 2 + species, which can occur near defects or their aggregates, cannot be directly translated in characteristic shifts of the core levels. The width of the defect-induced in-gap states is found to depend critically on the arrangement of the defects. This also has consequences for the spectroscopic signatures observed in so-called resistive switching phenomena. View Full-Text
Keywords: perovskite oxides; defect states; density functional theory perovskite oxides; defect states; density functional theory
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Al-Zubi, A.; Bihlmayer, G.; Blügel, S. Electronic Structure of Oxygen-Deficient SrTiO3 and Sr2TiO4. Crystals 2019, 9, 580.

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