TY  - JOUR
A1  - Jeschke, Harald O.
A1  - Shen, Juan
A1  - Valentí, Roser
T1  - Localized versus itinerant states created by multiple oxygen vacancies in SrTiO3
T2  - New Journal of Physics
N2  - Oxygen vacancies in strontium titanate surfaces (SrTiO3) have been linked to the presence of a two-dimensional electron gas with unique behavior. We perform a detailed density functional theory study of the lattice and electronic structure of SrTiO3 slabs with multiple oxygen vacancies, with a main focus on two vacancies near a titanium dioxide terminated SrTiO3 surface. We conclude based on total energies that the two vacancies preferably inhabit the first two layers, i.e. they cluster vertically, while in the direction parallel to the surface, the vacancies show a weak tendency towards equal spacing. Analysis of the nonmagnetic electronic structure indicates that oxygen defects in the surface TiO2 layer lead to population of Ti ${{t}_{2g}}$ states and thus itinerancy of the electrons donated by the oxygen vacancy. In contrast, electrons from subsurface oxygen vacancies populate Ti eg states and remain localized on the two Ti ions neighboring the vacancy. We find that both the formation of a bound oxygen-vacancy state composed of hybridized Ti 3eg and 4p states neighboring the oxygen vacancy as well as the elastic deformation after extracting oxygen contribute to the stabilization of the in-gap state.
KW  - perovskite oxides
KW  - oxygen vacancies
KW  - density functional theory
KW  - electronic structure
Y1  - 2015
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/79357
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-793574
SN  - 1367-2630
VL  - 17
IS  - 023034
PB  - IOP Publishing
CY  - [London]
ER  -