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The effect of a variety of intrinsic defects and defect clusters in bulk and thin films of SrTiO$_3$ on ferroelectric polarization and switching mechanism is investigated by means of density-functional-theory (DFT) based calculations and the Berry phase approach. Our results show that both the titanium Ti$_mathrm{Sr}^{bullet bullet}$ and strontium Sr$_mathrm{Ti}^{}$ antisite defects induce ferroelectric polarization in SrTiO$_3$, with the Ti$_mathrm{Sr}^{bullet bullet}$ defect causing a more pronounced spontaneous polarization and higher activation barriers of polarization reversal than Sr$_mathrm{Ti}^{}$. 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 SrTiO$_3$ 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 SrTiO$_{3}$.
Ionic crystals terminated at oppositely charged polar surfaces are inherently unstable and expected to undergo surface reconstructions to maintain electrostatic stability. Essentially, an electric field that arises between oppositely charged atomic p
We study a model SrTiO$_3$ interface in which conduction $t_{2g}$ electrons couple to the ferroelectric (FE) phonon mode. We treat the FE mode within a self-consistent phonon theory that captures its quantum critical behavior, and show that proximity
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