Lattice relaxations around individual dopant atoms in 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>SrTi</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>

Salmani-Rezaie, Salva; Kim, Honggyu; Ahadi, Kaveh; Stemmer, Susanne

doi:10.1103/physrevmaterials.3.114404

Cited by 8 publications

(6 citation statements)

References 40 publications

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“…Large, random displacements are therefore associated with the Sm dopant atoms. The complex displacement fields around the dopant atoms are similar to those analyzed in detail in ref for unstrained Sm-doped SrTiO 3 films and involve Ti–O columns moving away from the Sm dopants. This is not a size effect but due to electronic/electrostatic interactions .…”

Section: Resultssupporting

confidence: 72%

“…This is not a size effect but due to electronic/electrostatic interactions . In keeping with the expected behavior of a point defect, − the displacements due to the Sm dopants do not form correlated nanodomains but only affect the atom columns in their immediate vicinity (see also ref ). We also note that the Sm dopants are the main point defect in these films.…”

Section: Resultsmentioning

confidence: 55%

“…The polarization (displacement) vector is defined as the difference between the center of mass of four neighboring Sr columns and the Ti–O column position obtained by Gaussian fitting. As shown previously, quantitative analysis of HAADF images allows for determining the positions of individual dopant atoms in SrTiO 3 , and the displacement of the Ti–O columns around them …”

Section: Methodsmentioning

confidence: 68%

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Polar Nanodomains in a Ferroelectric Superconductor

2020

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The mechanisms by which itinerant carriers compete with polar crystal distortions are a key unresolved issue for polar superconductors, which offer new routes to unconventional Cooper pairing. Strained, doped SrTiO 3 films undergo successive ferroelectric and superconducting transitions, making them ideal candidates to elucidate the nature of this competition. Here, we reveal these interactions using scanning transmission electron microscopy studies of the evolution of polar nanodomains as a function of doping. These nanodomains are a precursor to the ferroelectric phase and a measure of long-range Coulomb interactions. With increasing doping, the magnitude of the polar displacements, the nanodomain size, and the Curie temperature are systematically suppressed. In addition, we show that disorder caused by the dopant atoms themselves presents a second contribution to the destabilization of the ferroelectric state. The results provide evidence for two distinct mechanisms that suppress the polar transition with doping in a ferroelectric superconductor.

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Section: Resultssupporting

confidence: 72%

Section: Resultsmentioning

confidence: 55%

Section: Methodsmentioning

confidence: 68%

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Polar Nanodomains in a Ferroelectric Superconductor

2020

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“…Images of polar regions above the Curie temperature of ferroelectric SrTiO 3 would provide the most direct evidence of an order-disorder transition. Atomic resolution high-angle annular dark-field imaging in scanning transmission electron microscopy (HAADF-STEM) is a powerful technique that is capable of determining the atomic column positions with picometer precision [40][41][42][43] and, consequently, should be able to detect regions that contain Ti columns that are off-centered from their nonpolar positions. Here, we use HAADF-STEM to measure static Ti-column displacement vectors at room temperature in the paraelectric phase of compressively strained SrTiO 3 films, which undergo a ferroelectric transition below 140 K [26,27,44].…”

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confidence: 99%

Order-Disorder Ferroelectric Transition of Strained SrTiO3

et al. 2020

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SrTiO 3 is an incipient ferroelectric that is believed to exhibit a prototype displacive, soft mode ferroelectric transition when subjected to mechanical stress or alloying. We use high-angle annular darkfield imaging in scanning transmission electron microscopy to reveal local polar regions in the roomtemperature, paraelectric phase of strained SrTiO 3 films, which undergo a ferroelectric transition at low temperatures. These films contain nanometer-sized domains in which the Ti columns are displaced. In contrast, these nanodomains are absent in unstrained films, which do not become ferroelectric. The results show that the ferroelectric transition of strained SrTiO 3 is an order-disorder transition. We discuss the impact of the results on the nature of the ferroelectric transition of SrTiO 3 .

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“…Figure 2 highlights the effect of doping and free charge carriers on the formation of polar domains in the strained and doped films. Sm dopants cause local lattice distortion in SrTiO3 films [3]. Color contour maps of Sm doped samples show the increase in lattice distortion caused by the Sm dopant (~0.5% (a), ~1%(b) and ~2%(c)).…”

mentioning

confidence: 99%