Moloud Kaviani^1*, Ulrich Aschauer^1*

1 Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland

* Corresponding authors emails: moloud.kaviani@unibe.ch, ulrich.aschauer@unibe.ch

DOI10.24435/materialscloud:1y-q7 [version v1]

Publication date: Jan 18, 2022

How to cite this record

Moloud Kaviani, Ulrich Aschauer, Surface and interface effects in oxygen deficient SrMnO3 thin films grown on SrTiO3, Materials Cloud Archive 2022.6 (2022), https://doi.org/10.24435/materialscloud:1y-q7

Description

Complex oxide functionality, such as ferroelectricity, magnetism or superconductivity is often achieved in epitaxial thin-film geometries. Oxygen vacancies tend to be the dominant type of defect in these materials but a fundamental understanding of their stability and electronic structure has so far mostly been established in the bulk or strained bulk, neglecting interfaces and surfaces present in a thin-film geometry. We investigate here, via density functional theory calculations, oxygen vacancies in the model system of a SrMnO3 (SMO) thin film grown on a SrTiO3 (STO) (001) substrate. Structural and electronic differences compared to bulk SMO result mainly from undercoordination at the film surface. The changed crystal field leads to a depletion of subsurface valence-band states and transfer of this charge to surface Mn atoms, both of which strongly affect the defect chemistry in the film. The result is a strong preference of oxygen vacancies in the surface region compared to deeper layers. Finally, for metastable oxygen vacancies in the substrate, we predict a spatial separation of the defect from its excess charge, the latter being accommodated in the film but close to the substrate boundary. These results show that surface and interface effects lead to significant differences in stability and electronic structure of oxygen vacancies in thin-film geometries compared to the (strained) bulk.

Materials Cloud sections using this data

Files

File name	Size	Description
SMO-STO.tar.gz MD5md5:7a51f66e67cd4c050343c4e786303dd1	371.2 MiB	The compressed file contains the jupyter notebook and the folders with the data used in the jupyter notebook to produce figure 2 found in the publication.
README.txt MD5md5:09e98731778311c2ada4f0a029df55de	926 Bytes	The README file contains information on the notebook and data stored in the archive.

License

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External references

Keywords

SNSF CSCS thin film SrMnO3 SrTiO3 oxygen vacancy crystal field surface interface