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Watanabe Y. Examination of permittivity for depolarization field of ferroelectric by ab initio calculation, suggesting hidden mechanisms. Sci Rep 2021; 11:2155. [PMID: 33495499 PMCID: PMC7835357 DOI: 10.1038/s41598-021-81237-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/01/2021] [Indexed: 11/16/2022] Open
Abstract
Electrostatics of depolarization field Ed in relation to the polarization is studied. In particular, the value of permittivity for Ed (εd) in prototypical situations of ferroelectrics, including Mehta formula, is examined by ab initio calculations. By using spontaneous polarization PS corresponding to accurate experiment ones, we show εd = 1, which suggests that the results of εd ≫ 1 indicate hidden mechanisms; εd = 1 suggests that the effect of Ed is significant to induce intriguing important phenomena overlooked by εd ≫ 1. A bridge between εd = 1 and εd ≫ 1, i.e. the consistency of εd = 1 with conventional results is presented. The exact electrostatic equality of head-to-head-tail-to-tail domains to free-standing ferroelectrics is deduced. Hence, most stoichiometric clean freestanding monodomain ferroelectrics and head-to-head-tail-to-tail domains are shown unstable regardless of size, unless partially metallic. This verifies the previous results in a transparent manner. This conclusion is shown consistent with a recent hyperferroelectric LiBeSb and "freestanding" monolayer ferroelectrics, of which origin is suggested to be adsorbates. In addition, this restriction is suggested to break in externally strained ultrathin ferroelectrics. The macroscopic formulas of Ed are found valid down to a several unit-cells, when electronic and atomic-scale surface effects are unimportant and accurate PS is used.
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Song C, Gao J, Liu J, Yang Y, Tian C, Hong J, Weng H, Zhang J. Atomically Resolved Edge States on a Layered Ferroelectric Oxide. ACS APPLIED MATERIALS & INTERFACES 2020; 12:4150-4154. [PMID: 31885250 DOI: 10.1021/acsami.9b20580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The emerging surface/edge electronic phases driven by broken symmetry effects have attracted great attention in low-dimensional electronic systems. However, experimental proof on their existence in ferroelectric oxides at the atomic scale is still missing. In this work, metallic surface states are observed on layered Bi2WO6 by scanning tunneling microscopy/spectroscopy. Differential conductance is remarkably enhanced near the step edge compared with that on the terrace, forming a one-dimensional edge state. Density functional theory calculations verify that symmetry breaking at the surface determines the electronic structures and O 2p orbitals contribute the most to the density of states around the Fermi level. Our discovery provides a new strategy toward the hidden phases on other correlated oxide surfaces.
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Affiliation(s)
- Chuangye Song
- Department of Physics , Beijing Normal University , Beijing 100875 , China
- Institute of Physics , Chinese Academy of Science , Beijing 100190 , China
- School of Physics , University of Chinese Academy of Sciences , Beijing 100049 , China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , China
| | - Jiacheng Gao
- Institute of Physics , Chinese Academy of Science , Beijing 100190 , China
- School of Physics , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Junyan Liu
- School of Aerospace Engineering , Beijing Institute of Technology , Beijing 100081 , China
| | - Yuben Yang
- Department of Physics , Beijing Normal University , Beijing 100875 , China
| | - Chengfeng Tian
- Department of Physics , Beijing Normal University , Beijing 100875 , China
| | - Jiawang Hong
- School of Aerospace Engineering , Beijing Institute of Technology , Beijing 100081 , China
| | - Hongming Weng
- Institute of Physics , Chinese Academy of Science , Beijing 100190 , China
- School of Physics , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Jinxing Zhang
- Department of Physics , Beijing Normal University , Beijing 100875 , China
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Watanabe Y. Calculation of strained BaTiO3 with different exchange correlation functionals examined with criterion by Ginzburg-Landau theory, uncovering expressions by crystallographic parameters. J Chem Phys 2018; 148:194702. [DOI: 10.1063/1.5022319] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yukio Watanabe
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan
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Kalinin SV, Kim Y, Fong DD, Morozovska AN. Surface-screening mechanisms in ferroelectric thin films and their effect on polarization dynamics and domain structures. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:036502. [PMID: 29368693 DOI: 10.1088/1361-6633/aa915a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
For over 70 years, ferroelectric materials have been one of the central research topics for condensed matter physics and material science, an interest driven both by fundamental science and applications. However, ferroelectric surfaces, the key component of ferroelectric films and nanostructures, still present a significant theoretical and even conceptual challenge. Indeed, stability of ferroelectric phase per se necessitates screening of polarization charge. At surfaces, this can lead to coupling between ferroelectric and semiconducting properties of material, or with surface (electro) chemistry, going well beyond classical models applicable for ferroelectric interfaces. In this review, we summarize recent studies of surface-screening phenomena in ferroelectrics. We provide a brief overview of the historical understanding of the physics of ferroelectric surfaces, and existing theoretical models that both introduce screening mechanisms and explore the relationship between screening and relevant aspects of ferroelectric functionalities starting from phase stability itself. Given that the majority of ferroelectrics exist in multiple-domain states, we focus on local studies of screening phenomena using scanning probe microscopy techniques. We discuss recent studies of static and dynamic phenomena on ferroelectric surfaces, as well as phenomena observed under lateral transport, light, chemical, and pressure stimuli. We also note that the need for ionic screening renders polarization switching a coupled physical-electrochemical process and discuss the non-trivial phenomena such as chaotic behavior during domain switching that stem from this.
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Affiliation(s)
- Sergei V Kalinin
- The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
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Yang T, Zhang X, Chen B, Guo H, Jin K, Wu X, Gao X, Li Z, Wang C, Li X. The Evidence of Giant Surface Flexoelectric Field in (111) Oriented BiFeO 3 Thin Film. ACS APPLIED MATERIALS & INTERFACES 2017; 9:5600-5606. [PMID: 28097864 DOI: 10.1021/acsami.6b15162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this work, the surface structure of a single-domain epitaxial BiFeO3 film with (111) orientation was investigated by in situ grazing incidence X-ray diffraction and X-ray reflectivity. We found that a large strain gradient exists in the surface region (2-3 nm) of the BiFeO3 film. The strain gradient is approximately 107 m-1, which is 2 or 3 orders of magnitude larger than the value inside the film. Moreover, we found that a surface layer with a lower electron density compared with the underlying BiFeO3 layer exists on the surface of BiFeO3 film, and this layer exhibits an irreversible surface structure transition occurs at 500 K, which should be associated with the surface flexoelectric field. We considered that this large strain gradient is originated from the surface depolarization field of ferroelectrics. Our results suggest a coupling between the surface structure and the flexoelectricity and imply that the surface layer and properties would be controlled by the strain gradient in ferroelectric films.
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Affiliation(s)
- Tieying Yang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai, 201204, China
| | - Xingmin Zhang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai, 201204, China
| | - Bin Chen
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo, 315201, China
| | - Haizhong Guo
- Institute of Physics, Chinese Academy of Sciences , Beijing, 100190, China
| | - Kuijuan Jin
- Institute of Physics, Chinese Academy of Sciences , Beijing, 100190, China
| | - Xiaoshan Wu
- Department of Physics, Nanjing University , Nanjing, 210093, China
| | - Xingyu Gao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai, 201204, China
| | - Zhong Li
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai, 201204, China
| | - Can Wang
- Institute of Physics, Chinese Academy of Sciences , Beijing, 100190, China
| | - Xiaolong Li
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai, 201204, China
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Hong S, Nakhmanson SM, Fong DD. Screening mechanisms at polar oxide heterointerfaces. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:076501. [PMID: 27308889 DOI: 10.1088/0034-4885/79/7/076501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The interfaces of polar oxide heterostructures can display electronic properties unique from the oxides they border, as they require screening from either internal or external sources of charge. The screening mechanism depends on a variety of factors, including the band structure at the interface, the presence of point defects or adsorbates, whether or not the oxide is ferroelectric, and whether or not an external field is applied. In this review, we discuss both theoretical and experimental aspects of different screening mechanisms, giving special emphasis to ways in which the mechanism can be altered to provide novel or tunable functionalities. We begin with a theoretical introduction to the problem and highlight recent progress in understanding the impact of point defects on polar interfaces. Different case studies are then discussed, for both the high thickness regime, where interfaces must be screened and each interface can be considered separately, and the low thickness regime, where the degree and nature of screening can be manipulated and the interfaces are close enough to interact. We end with a brief outlook toward new developments in this rapidly progressing field.
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Affiliation(s)
- Seungbum Hong
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA. Department of Materials Science & Engineering, KAIST, Daejeon 305-701, Korea
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Huang S, Luo J, Yip HL, Ayazi A, Zhou XH, Gould M, Chen A, Baehr-Jones T, Hochberg M, Jen AKY. Efficient poling of electro-optic polymers in thin films and silicon slot waveguides by detachable pyroelectric crystals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:OP42-OP47. [PMID: 22213467 DOI: 10.1002/adma.201102874] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Indexed: 05/31/2023]
Abstract
Pyroelectric crystals are used as a conformal and detachable electric field source to efficiently pole electro-optic (E-O) polymers in both parallel-plate (transverse) and in-plane (quasi-longitudinal) configurations. Large Pockels coefficients in poled thin films and high tunability of resonance wavelength shift in hybrid polymer silicon slot waveguide ring-resonator modulators have been achieved using this method.
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Affiliation(s)
- Su Huang
- Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, USA
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Chisholm MF, Luo W, Oxley MP, Pantelides ST, Lee HN. Atomic-scale compensation phenomena at polar interfaces. PHYSICAL REVIEW LETTERS 2010; 105:197602. [PMID: 21231196 DOI: 10.1103/physrevlett.105.197602] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Indexed: 05/30/2023]
Abstract
The interfacial screening charge that arises to compensate electric fields of dielectric or ferroelectric thin films is now recognized as the most important factor in determining the capacitance or polarization of ultrathin ferroelectrics. Here we investigate using aberration-corrected electron microscopy and density-functional theory to show how interfaces cope with the need to terminate ferroelectric polarization. In one case, we show evidence for ionic screening, which has been predicted by theory but never observed. For a ferroelectric film on an insulating substrate, we found that compensation can be mediated by an interfacial charge generated, for example, by oxygen vacancies.
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Affiliation(s)
- Matthew F Chisholm
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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Lui KM, Leang PS, Kam YK, Lau WM. Measurements of ion-induced ferroelectric emission and surface charge dynamics on LiTaO3(0001) by time-of-flight scattering and recoiling spectrometry (TOF-SARS). SURF INTERFACE ANAL 2006. [DOI: 10.1002/sia.2360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Kuffer O, Maggio-Aprile I, Fischer Ø. Nanoscale ferroelectric field-effect writing and reading using scanning tunnelling spectroscopy. NATURE MATERIALS 2005; 4:378-382. [PMID: 15834416 DOI: 10.1038/nmat1364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 02/11/2005] [Indexed: 05/24/2023]
Abstract
Control of the density of mobile charge carriers using electric fields is widely used in a variety of metal-insulator-semiconductor structures and is the governing principle behind the operation of field-effect transistors. Ferroelectric materials possessing a switchable and non-volatile polarization field can be used as insulating layers, revealing new opportunities for device applications. Advances in material processing and in particular complex oxide thin-film growth mean that high-quality field-effect devices can be based on ferroelectric/metallic oxide heterostructures. In addition, advances in local probe techniques such as atomic force microscopy allow them to be used in the imaging and study of small ferroelectric domain structures in bulk crystals and thin films. Meanwhile, scanning tunnelling microscopy and spectroscopy have established themselves as powerful techniques for atomic manipulation and nanometre-resolution electron tunnelling spectroscopy. Here, a scanning tunnelling microscope is used to investigate the ferroelectric field effect in all-perovskite heterostructures. Scanning tunnelling spectroscopy allows us to probe the local electronic properties of the polarized channel of a ferroelectric field-effect device as a function of the field orientation. This technique can be used to read and write ferroelectric field-induced regions with a size as low as 20 nm.
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Affiliation(s)
- Olivier Kuffer
- Condensed Matter Physics Department, University of Geneva, Switzerland.
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Chu MW, Szafraniak I, Scholz R, Harnagea C, Hesse D, Alexe M, Gösele U. Impact of misfit dislocations on the polarization instability of epitaxial nanostructured ferroelectric perovskites. NATURE MATERIALS 2004; 3:87-90. [PMID: 14730357 DOI: 10.1038/nmat1057] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2003] [Accepted: 12/10/2003] [Indexed: 05/24/2023]
Abstract
Defects exist in almost all materials and defect engineering at the atomic level is part of modern semiconductor technology. Defects and their long-range strain fields can have a negative impact on the host materials. In materials with confined dimensions, the influence of defects can be even more pronounced due to the enhanced relative volume of the 'defective' regions. Here we report the dislocation-induced polarization instability of (001)-oriented Pb(Zr(0.52)Ti(0.48))O(3) (PZT) nanoislands, with an average height of approximately 9 nm, grown on compressive perovskite substrates. Using quantitative high-resolution electron microscopy, we visualize the strain fields of edge-type misfit dislocations, extending predominantly into a PZT region with a height of approximately 4 nm and width of approximately 8 nm. The lattice within this region deviates from the regular crystal structure. Piezoresponse force microscopy indicates that such PZT nanoislands do not show ferroelectricity. Our results suggest that misfit engineering is indispensable for obtaining nanostructured ferroelectrics with stable polarization.
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Affiliation(s)
- Ming-Wen Chu
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Saale), Germany.
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Streiffer SK, Eastman JA, Fong DD, Thompson C, Munkholm A, Ramana Murty MV, Auciello O, Bai GR, Stephenson GB. Observation of nanoscale 180 degrees stripe domains in ferroelectric PbTiO3 thin films. PHYSICAL REVIEW LETTERS 2002; 89:067601. [PMID: 12190610 DOI: 10.1103/physrevlett.89.067601] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2002] [Indexed: 05/23/2023]
Abstract
We report the observation of periodic 180 degrees stripe domains below the ferroelectric transition in thin films. Epitaxial PbTiO3 films of thickness d=1.6 to 42 nm on SrTiO3 substrates were studied using x-ray scattering. Upon cooling below T(C), satellites appeared around Bragg peaks indicating the presence of 180 degrees stripe domains of period Lambda=3.7 to 24 nm. The dependence of Lambda on d agrees well with theory including epitaxial strain effects, while the suppression of T(C) for thinner films is significantly larger than that expected solely from stripe domains.
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Affiliation(s)
- S K Streiffer
- Materials Science Division, Argonne National Laboratory, Illinois 60439, USA.
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