Effect of intrinsic point defects on ferroelectric polarization behavior of SrTiO₃

Authors

Konstantin Klyukin, University of Nebraska-LincolnFollow
Vitaly Alexandrov, University of Nebraska - LincolnFollow

Date of this Version

2017

Document Type

Article

Citation

PHYSICAL REVIEW B 95, 035301 (2017)

Comments

Copyright 2017 American Physical Society

Abstract

The effect of a variety of intrinsic defects and defect clusters in bulk and thin films of SrTiO₃ on ferroelectric polarization and switching mechanisms is investigated by means of density-functional-theory based calculations and the Berry phase approach. Our results show that both the titanium Ti••_Sr and strontium Srⁿ_Ti antisite defects induce ferroelectric polarization in SrTiO₃, with the Ti••_Sr defect causing a more pronounced spontaneous polarization and higher activation barriers of polarization reversal than Srⁿ_Ti. The presence of oxygen vacancies bound to the antisite defects can either enhance or diminish polarization depending on the configuration of the defect pair, but it always leads to larger activation barriers of polarization switching as compared to the antisite defects with no oxygen vacancies.We also show that the magnitude of spontaneous polarization in SrTiO₃ can be tuned by controlling the degree of Sr/Ti nonstroichiometry. Other intrinsic point defects such as Frenkel defect pairs and electron small polarons also contribute to the emergence of ferroelectric polarization in SrTiO₃.