Defect accommodation in off-stoichiometric (SrTiO3)<i>n</i>SrO Ruddlesden–Popper superlattices studied with positron annihilation spectroscopy

Dawley, Natalie M.; Egger, Werner; Barone, Matthew R.; Kourkoutis, Lena F.; Keeble, D. J.; Schlom, D. G.

doi:10.1063/5.0011136

Cited by 13 publications

(6 citation statements)

References 51 publications

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“…Errors in composition, on the other hand, can be accommodated via the formation of extended defects such as rock salt faults: half unit cell stacking faults formed by additional AO inclusions [50][51][52] . In homoepitaxial Sr n+1 Ti n O 3n+1 , for example, up to 5% excess strontium can be accommodated by the formation of additional SrO rock salt layers, while strontium deficiency results in missing rock salt layers [53][54][55][56][57] .…”

Section: Mbe Synthesis Of Ruddlesden-popper Nickelatesmentioning

confidence: 99%

Limits to the strain engineering of layered square-planar nickelate thin films

et al. 2023

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The layered square-planar nickelates, Ndn+1NinO2n+2, are an appealing system to tune the electronic properties of square-planar nickelates via dimensionality; indeed, superconductivity was recently observed in Nd6Ni5O12 thin films. Here, we investigate the role of epitaxial strain in the competing requirements for the synthesis of the n = 3 Ruddlesden-Popper compound, Nd4Ni3O10, and subsequent reduction to the square-planar phase, Nd4Ni3O8. We synthesize our highest quality Nd4Ni3O10 films under compressive strain on LaAlO3 (001), while Nd4Ni3O10 on NdGaO3 (110) exhibits tensile strain-induced rock salt faults but retains bulk-like transport properties. A high density of extended defects forms in Nd4Ni3O10 on SrTiO3 (001). Films reduced on LaAlO3 become insulating and form compressive strain-induced c-axis canting defects, while Nd4Ni3O8 films on NdGaO3 are metallic. This work provides a pathway to the synthesis of Ndn+1NinO2n+2 thin films and sets limits on the ability to strain engineer these compounds via epitaxy.

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Section: Mbe Synthesis Of Ruddlesden-popper Nickelatesmentioning

confidence: 99%

Limits to the strain engineering of layered square-planar nickelate thin films

et al. 2023

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“…In principle, MBE enables one to precisely control the monolayer deposition times and hence synthesize a generic Ruddlesden-Popper compound of arbitrary order n. There are key differences however between the Ruddlesden-Popper nickelates and other Ruddlesden-Popper systems such as the more commonly studied Sr n+1 Ti n O 3n+1 which make the direct translation of other synthetic calibration techniques onto the nickelates difficult. In Sr n+1 Ti n O 3n+1 compounds, deviations from perfect stoichiometry by as much as 5+% often result in imperfect superlattices with rock salt intergrowths or missing rock salt layers but without substantial phase segregation [21,22]. Errors in monolayer dosing times can then be quantitatively estimated and adjusted for purely based on x-ray diffraction spectra of the superlattice phase [23].…”

Section: A Synthesis Via Mbementioning

confidence: 99%

Synthesis and electronic properties of Nd$_{n+1}$Ni$_{n}$O$_{3n+1}$ Ruddlesden-Popper nickelate thin films

Pan,

Song,

Segedin

et al. 2022

Preprint

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The rare-earth nickelates possess a diverse set of collective phenomena including metal-toinsulator transitions, magnetic phase transitions, and, upon chemical reduction, superconductivity. Here, we demonstrate epitaxial stabilization of layered nickelates in the Ruddlesden-Popper form, Ndn+1NinO3n+1, using molecular beam epitaxy. By optimizing the stoichiometry of the parent perovskite NdNiO3, we can reproducibly synthesize the n = 1−5 member compounds. X-ray absorption spectroscopy at the O K and Ni L edges indicate systematic changes in both the nickel-oxygen hybridization level and nominal nickel filling from 3d 8 to 3d 7 as we move across the series from n = 1 to n = ∞. The n = 3 − 5 compounds exhibit weakly hysteretic metal-to-insulator transitions with transition temperatures that depress with increasing order toward NdNiO3 (n = ∞).

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“…Ruddlesden-Popper thin films were grown by molecular beam epitaxy (MBE) as described previously. 9,19,20 Cross-sectional STEM specimens were prepared using the standard focused ion beam (FIB) lift-out process on a Thermo Scientific Helios G4 UX FIB or FEI Strata 400 FIB equipped with an Omniprobe AutoProbe 200 nanomanipulator. HAADF-STEM images were acquired on an aberration-corrected FEI Titan Themis operating at 120 kV (Sr…”

Section: A Data Collectionmentioning

confidence: 99%

Atomic-scale mapping and quantification of local Ruddlesden-Popper phase variations

Fleck¹,

Barone²,

Nair³

et al. 2022

Preprint

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The Ruddlesden-Popper (A n+1 B n O 3n+1 ) compounds are a highly tunable class of materials whose functional properties can be dramatically impacted by their structural phase n. The negligible energetic differences associated with forming a sample with a single value of n versus a mixture of n makes the growth of these materials difficult to control and can lead to local atomic-scale structural variation arising from small stoichiometric deviations. In this work, we present a Python analysis platform to detect, measure, and quantify the presence of different n-phases based on atomic-resolution scanning transmission electron microscopy (STEM) images in a statistically rigorous manner. We employ phase analysis on the 002 Bragg peak to identify horizontal Ruddlesden-Popper faults which appear as regions of high positive compressive strain within the lattice image, allowing us to quantify the local structure. Our semi-automated technique offers statistical advantages by considering effects of finite projection thickness, limited fields of view, and precise sampling rates. This method retains the real-space distribution of layer variations allowing for a spatial mapping of local n-phases, enabling both quantification of intergrowth occurrence as well as qualitative description of their distribution, opening the door to new insights and levels of control over a range of layered materials.

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Defect accommodation in off-stoichiometric (SrTiO3)nSrO Ruddlesden–Popper superlattices studied with positron annihilation spectroscopy

Cited by 13 publications

References 51 publications

Limits to the strain engineering of layered square-planar nickelate thin films

Limits to the strain engineering of layered square-planar nickelate thin films

Synthesis and electronic properties of Nd$_{n+1}$Ni$_{n}$O$_{3n+1}$ Ruddlesden-Popper nickelate thin films

Atomic-scale mapping and quantification of local Ruddlesden-Popper phase variations

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