Coexistence of trapped and free excess electrons in SrTiO3

Autor(en)

Xianfeng Hao, Zhiming Wang, Michael Schmid, Ulrike Diebold, Cesare Franchini

Abstrakt

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(en)

Computergestützte Materialphysik

Externe Organisation(en)

Yanshan University, Technische Universität Wien, Universität Wien

Journal

Physical Review B

Band

91

Anzahl der Seiten

6

ISSN

1098-0121

DOI

https://doi.org/10.1103/PhysRevB.91.085204

Publikationsdatum

02-2015

Peer-reviewed

Ja

ÖFOS 2012

103025 Quantenmechanik, 103036 Theoretische Physik, 103015 Kondensierte Materie, 103009 Festkörperphysik

Schlagwörter

ASJC Scopus Sachgebiete

Electronic, Optical and Magnetic Materials, Condensed Matter Physics

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/5f09d006-273a-4b67-8052-5c3bea507a1d