Possible absence of critical thickness and size effect in ultrathin perovskite ferroelectric films

Gao, Peng; Zhang, Zhangyuan; Li, Mingqiang; Ishikawa, Ryo; Feng, Bin; Liu, Heng Jui; Huang, Ying; Shibata, Naoya; Ma, Xiumei; Chen, Shulin; Zhang, Jingmin; Liu, Kaihui; Wang, En Ge; Yu, Dapeng; Liao, Lei; Chu, Ying‐Hao; Ikuhara, Yuichi

doi:10.1038/ncomms15549

Cited by 119 publications

(95 citation statements)

References 42 publications

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“…In a perovskite structure, the rigid oxygen octahedron exhibits various structural distortions driven by stain and electrostatic conditions, underpinning vast functionalities. Many efforts have been paid to precisely measure the local distortion in perovskite structures by various microscopy techniques [2-4, 26, 33-47] but not much in ABF-STEM imaging [13,14,29]. In our work, we use a probe corrected ARM300CF (JEOL Ltd.) microscope, operating at 300 kV, and we simultaneously record both ADF-and ABF-STEM images, where a convergence semi-angle is 24 mrad, detector collection semi-angles spanning from 65 to 200 mrad for ADF and 12 to 24 mrad for ABF imaging, respectively.…”

Section: Introductionmentioning

confidence: 99%

Picometer-scale atom position analysis in annular bright-field STEM imaging

et al. 2018

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We study the effects of specimen mistilt on the picometer-scale measurement of local structure by combing experiment and simulation in annular bright-field scanning transmission electron microscopy (ABF-STEM). A relative distance measurement method is proposed to separate the tilt effects from the scan noise and sample drift induced image distortion. We find that under a typical experimental condition a small specimen tilt (∼6 mrad) in 25 nm thick SrTiO along [001] causes 11.9 pm artificial displacement between O and Sr/TiO columns in ABF image, which is more than 3 times of scan noise and sample drift induced image distortion ∼3.2 pm, suggesting the tilt effect could be dominant for the quantitative analysis of ABF images. The artifact depends on the crystal mistilt angle, specimen thickness, defocus, convergence angle and uncorrected aberration. Our study provides useful insights into detecting and correcting tilt effects during both experiment operation and data analysis to extract the real structure information and avoid mis-interpretations of atomic structure as well as the properties such as oxygen octahedral distortion/shift.

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Section: Introductionmentioning

confidence: 99%

Picometer-scale atom position analysis in annular bright-field STEM imaging

et al. 2018

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“…For example, atomic thickness ferroelectricity has been found in monolayer chalcogenides: M (1) X, M (2) X 2 , and M 2 (3) X 3 (M (1) = Ge, Sn; M (2) = Mo, W; M (3) = Al, Ga, In; X = S, Se, Te). Fortunately, more and more atomic thickness spontaneous electric polarization has been discovered in ionic compound monolayer with the puckered lattice structure.…”

Section: Doi: 101002/aelm201800475mentioning

confidence: 99%

“…[1][2][3] For typical perovskite ferroelectrics, BaTiO 3 and PbTiO 3 , ferroelectricity will vanish when the films thickness are reduced respectively to six unit cells (24 Å) [1] and three unit cells (12 Å). Overcoming the critical thickness effect will clear the way for the further miniaturization of ferroelectric devices, which have been attracting extensive research interest for many years.…”

Section: Introductionmentioning

confidence: 99%

“…Overcoming the critical thickness effect will clear the way for the further miniaturization of ferroelectric devices, which have been attracting extensive research interest for many years. [3] In order to verify the absence of critical thickness, it is natural to look for evidence in 2D materials with atomic thickness, which are relatively small in size compared to ultrathin www.advelectronicmat.de while monolayer β-Se has a considerable in-plane spontaneous polarizations. [2] Recently, it was reported that the PbZr 0.2 Ti 0.8 O 3 has a residual polarization at 1.5 unit cells (6 Å), this means that the absence of critical thickness is possible due to the structural imperfection at the interface and surface.…”

Section: Introductionmentioning

confidence: 99%

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High Bipolar Conductivity and Robust In‐Plane Spontaneous Electric Polarization in Selenene

Wang

Tang

Jiang

et al. 2018

Adv Elect Materials

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perovskite films. Fortunately, more and more atomic thickness spontaneous electric polarization has been discovered in ionic compound monolayer with the puckered lattice structure. For example, atomic thickness ferroelectricity has been found in monolayer chalcogenides: M (1) X, M (2) X 2 , and M 2 (3) X 3 (M (1) = Ge, Sn; M (2) = Mo, W; M (3) = Al, Ga, In; X = S, Se, Te). [4][5][6][7] Fascinatingly more, ferroelectricity was also discovered in the 2D elemental materials, such as phosphorene nanoribbons, [8] group-V (As, Sb, Bi) monolayer [9] and tellurium multilayers, [10] which was previously thought impossible because of the stabilized high symmetry in elemental bulk structures and the equal distribution of charge per atom. In other words, bulk element cannot satisfy the two main mechanisms of ferroelectric polarization: ion-displacement and electronic polarization. Therefore, the study of elemental ferroelectricity involved in structural reconstruction is a fundamental question and will undoubtedly expand the application of ferroelectrics in device miniaturization.In the last decade, intensive efforts have been devoted to discover the potential 2D materials for the application of micro-nano electronic devices. [11][12][13][14][15] Common 2D materials have a layered 3D structure with covalently bonded, atomically thin layers held together by weak van der Waals forces. Through high-throughput computations, however, more than a thousand 2D materials with various functions have been verified or predicted, even including elemental 2D metals. [16,17] Among elemental 2D materials, group-VI elements have been predicted and successfully fabricated at last year. [18][19][20][21] In the new study, Jia and co-workers point out the underlying formation mechanism of tellurene is inherently rooted in the multi valency nature of Te, and further predict the importance of multivalency in the layering behavior of Se. [18] Motivated by this discovery, we have performed a systematic densityfunctional study on various dimension elemental tellurium, and found that the atomic structure and electronic properties of 2D monolayers and bilayers of tellurene close related to the multivalency of Te. [22] In this paper, we found that the charge transfer from the central to the outer atoms amounts to 0.18 and 0.04 e in aand β-Se, respectively. Se has the multivalent nature with both metal and nonmetal characteristics as the previously reported. In addition, we have demonstrated that monolayer a-Se possesses a rather high carrier mobility, Selenene has been predicted as a new member of an atomically thin 2D crystalline material family as of last year. With first principle calculations, two different stable phases of selenene, one with the 1T-MoS 2 -like structure (α-Se) and the other with alternating arrangement structure of deformed four-membered and six-membered rings (b-Se) are identified. Further research indicates that monolayer α-Se exhibits excellent bipolar conductivity, possessing rather high hole mobility close to that of graphene,...

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“…Bismuth ferrite (BiFeO 3 ) is a prototypical room temperature multiferroic, and barium titanate (BaTiO 3 ) , on the other hand, is a ferroelectric . Previous study has shown that at some critical thickness (maximum thickness) in perovskite ferroelectric films, the localized enhancement of the electromagnetic field vanishes . The limit of the localized enhancement field in ultrathin film has been therefore established experimentally and theoretically and was found to be dependent on the material .…”

Section: Introductionmentioning

confidence: 99%

Near‐field enhancements and surface plasmon polaritons with multifunctional oxide thin films

Dab

Thomas

Hajlaoui

et al. 2018

J Raman Spectroscopy

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The thickness of multifunctional oxide films directly affects the localized enhancement of the electromagnetic field and hence is a key factor for realizing novel photonic or optoelectronic devices. To this end, we theoretically exploit the principle of tip‐enhanced Raman spectroscopy on the surface of multifunctional oxide films (bismuth ferrite and barium titanate) on a gold substrate. An electromagnetic field enhancement of up to 104 in close proximity of the tip apex was obtained. The good agreement between simulation and experiment of spatial resolution of the tip supports the validity of our model. By investigation of surface plasmon polaritons that propagates at the interface between the multifunctional film and the gold substrate, we demonstrated a thickness dependent propagation length and amplitude. This study indicates a critical thickness of the films above which neither a considerable near‐field nor a tip‐mediated excitation are observed. This confirms the validity, promise, and power of tip‐enhanced Raman spectroscopy technique for the analysis of various electro‐optic materials.

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Possible absence of critical thickness and size effect in ultrathin perovskite ferroelectric films

Cited by 119 publications

References 42 publications

Picometer-scale atom position analysis in annular bright-field STEM imaging

Picometer-scale atom position analysis in annular bright-field STEM imaging

High Bipolar Conductivity and Robust In‐Plane Spontaneous Electric Polarization in Selenene

Near‐field enhancements and surface plasmon polaritons with multifunctional oxide thin films

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