Coexistence of trapped and free excess electrons in SrTiO3
- Author(s)
- Xianfeng Hao, Zhiming Wang, Michael Schmid, Ulrike Diebold, Cesare Franchini
- Abstract
The question whether excess electrons in SrTiO3 form free or trapped carriers is a crucial aspect for the electronic properties of this important material. This fundamental ambiguity prevents a consistent interpretation of the puzzling experimental situation, where results support one or the other scenario depending on the type of experiment that is conducted. Using density functional theory with an on-site Coulomb interaction U, we show that excess electrons form small polarons if the density of electronic carriers is higher than approximate to 10(20) cm(-3). Below this value, the electrons stay delocalized or become large polarons. For oxygen-deficient SrTiO3, small polarons confined to Ti3+ sites are immobile at low temperature but can be thermally activated into a conductive state, which explains the metal-insulator transition observed experimentally.
- Organisation(s)
- Computational Materials Physics
- External organisation(s)
- Yanshan University, Technische Universität Wien, University of Vienna
- Journal
- Physical Review B
- Volume
- 91
- No. of pages
- 6
- ISSN
- 1098-0121
- DOI
- https://doi.org/10.1103/PhysRevB.91.085204
- Publication date
- 02-2015
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103025 Quantum mechanics, 103036 Theoretical physics, 103015 Condensed matter, 103009 Solid state physics
- Keywords
- ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials, Condensed Matter Physics
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/5f09d006-273a-4b67-8052-5c3bea507a1d