Surface phase, morphology, and charge distribution transitions on vacuum and ambient annealed<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>(100)

Dagdeviren, Omur E.; Simon, Géza; Zou, Ke; Walker, Frederick J.; Ahn, Charles; Altman, Eric I.; Schwarz, Udo D.

doi:10.1103/physrevb.93.195303

Cited by 36 publications

(38 citation statements)

References 71 publications

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“…Along [001] the material is constructed of alternating TiO 2 and SrO planes with the SrO planes resembling a single (001) plane of rock salt‐structured SrO. Under the preparation conditions employed here, the surface displays a predominant TiO 2 termination . Meanwhile, SnTe forms a rock salt structure with a 0.6325 nm lattice constant at room temperature.…”

Section: Resultsmentioning

confidence: 99%

“…The pattern in Figure a for the SrTiO 3 substrate reveals strong (1 × 1) spots with a trace of a c (2 × 2) reconstruction. This pattern was recorded after subliming away a thick SnTe film at 800 K; since the SrTiO 3 surface is unaffected by annealing at 800 K in UHV (ultra‐high vacuum) for 30 min, the pattern reflects the surface state prior to growth even though the measurement was not performed in the growth chamber. The LEED pattern for a 400 uc SnTe film before it was sublimed away in Figure b shows that the substrate spots are replaced by a new, more compressed square pattern; there is no longer any evidence of a reconstruction; the [10] direction of the film surface matches that of the substrate; and that the diffraction features appear as arcs with an ≈15° spread.…”

Section: Resultsmentioning

confidence: 99%

“…This article describes the surface properties of SnTe films grown by molecular beam epitaxy (MBE) on undoped and unreduced, insulating SrTiO 3 (001), a common and inexpensive substrate for epitaxial growth . Although a better lattice match is typically desired, chalcogenides with closer fits to SnTe typically have small bandgaps, which would interfere with transport measurements and there are no widely available insulating oxide substrates that offer a substantially better lattice match.…”

Section: Introductionmentioning

confidence: 99%

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Length Scale and Dimensionality of Defects in Epitaxial SnTe Topological Crystalline Insulator Films

Dagdeviren

Zhou

Zou

et al. 2017

Adv Materials Inter

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surface states of topological insulators are protected by time reversal symmetry, which makes them impervious to nonmagnetic perturbations and restricts scattering. [1,3,4] For these reasons, topological insulators have garnered great interest. [1,2] Topological crystalline insulators (TCIs) are a subset of topological materials that are narrow band gap semiconductors in the bulk with gapless surface states; however, the topological surface states are protected by lattice symmetry rather than time reversal symmetry. [2,[5][6][7][8][9][10][11][12][13][14][15][16] Topological crystalline insulators have been theoretically predicted and experimentally realized on compounds with orbital degrees of freedom playing a similar role to spin in topological insulators; [2,[5][6][7][8][9][10][11][12][13][14][15][16] one such material is SnTe. [5][6][7][8][9][10][11][12][13][14][15][16] The key role played by surface symmetry in protecting the topological states suggests that the TCI properties can be manipulated by introducing symmetry breaking surface features. As a first step toward this goal, we have studied the epitaxial growth of SnTe films and characterized their structural and electronic properties. It will be shown that the growth process and subsequent postgrowth treatment creates characteristic defects that can alter the local electronic properties of the surface down to the atomic scale.Topological crystalline insulators (TCIs) are new materials with metallic surface states protected by crystal symmetry. The properties of molecular beam epitaxy grown SnTe TCI on SrTiO 3 (001) are investigated using scanning tunneling microscopy (STM), noncontact atomic force microscopy, low-energy and reflection high-energy electron diffraction, X-ray diffraction, Auger electron spectroscopy, and density functional theory. Initially, SnTe (111) and (001) surfaces are observed; however, the (001) surface dominates with increasing film thickness. The films grow island-by-island with the [011] direction of SnTe (001) islands rotated up to 7.5° from SrTiO 3 [010]. Microscopy reveals that this growth mechanism induces defects on different length scales and dimensions that affect the electronic properties, including point defects (0D); step edges (1D); grain boundaries between islands rotated up to several degrees; edge-dislocation arrays (2D out-of-plane) that serve as periodic nucleation sites for pit growth (2D in-plane); and screw dislocations (3D). These features cause variations in the surface electronic structure that appear in STM images as standing wave patterns and a nonuniform background superimposed on atomic features. The results indicate that both the growth process and the scanning probe tip can be used to induce symmetry breaking defects that may disrupt the topological states in a controlled way.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Length Scale and Dimensionality of Defects in Epitaxial SnTe Topological Crystalline Insulator Films

Dagdeviren

Zhou

Zou

et al. 2017

Adv Materials Inter

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“…In this work we follow the process of 30 min vacuum annealing steps as thoroughly investigated by Dagdeviren et al. 1 Under these conditions no changes in the step density of the STO(001) surface was observed, while the increased density of oxygen vacancies lead to a change in surface reconstructions. In contrast to this work we did not perform extensive ex-situ cleaning steps involving either oxygen annealing and/or acid treatment required to achieve large, regular terraces.…”

Section: S5 Sto Surface Characterisationmentioning

confidence: 99%

Ultrathin magnetite inFe3O4/MgOsuperlattices: Investigating the enhanced thin film magnetic moment

et al. 2017

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“…In the following, we focus on stoichiometry changes of the very surface of SrTiO 3 upon thermal reduction. It has been reported that annealing under reducing conditions leads to the evolution of a Ti‐rich surface with new reconstruction and eventually Ti 2 O 3 or TiO islands can form on the surface . In general, two different channels changing the chemical composition of the surface have to be taken into account, namely segregation and sublimation .…”

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confidence: 99%

Stability and Decomposition of Perovskite-Type Titanates upon High-Temperature Reduction

Rodenbücher

Meuffels

Speier

et al. 2017

Phys. Status Solidi RRL

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Controlling the properties of the surface region of ternary perovskite‐type titanates is of high importance in the field of future energy and information technologies. A common method to modify the surface of perovskite oxides such as SrTiO3 is annealing under vacuum conditions. Here we show that the local oxygen partial pressure near to the surface plays a crucial role during annealing. While the oxide is found to be macroscopically stable during high‐temperature reduction under standard vacuum conditions and only segregation effects on the nanoscale seem to take place, surface decomposition due to incongruent sublimation occurs as soon as an oxygen getter such as Ti is positioned close to the oxide. In consequence, owing to the high volatility of Sr‐containing species at very low oxygen pressures, a Sr‐depleted TiOx surface layer is formed. This effect might reveal an alternative possibility to tailor composition and structure of perovskite‐type titanate surfaces.

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Surface phase, morphology, and charge distribution transitions on vacuum and ambient annealedSrTiO3(100)

Cited by 36 publications

References 71 publications

Length Scale and Dimensionality of Defects in Epitaxial SnTe Topological Crystalline Insulator Films

Length Scale and Dimensionality of Defects in Epitaxial SnTe Topological Crystalline Insulator Films

Ultrathin magnetite inFe3O4/MgOsuperlattices: Investigating the enhanced thin film magnetic moment

Stability and Decomposition of Perovskite-Type Titanates upon High-Temperature Reduction

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