1
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Du M, Ji S, Zhang P, Tang Y, Liu Y. Enriching Nano-Heterointerfaces in Proton Conducting TiO 2-SrTiO 3@TiO 2 Yolk-Shell Electrolyte for Low-Temperature Solid Oxide Fuel Cells. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2401008. [PMID: 38867389 DOI: 10.1002/advs.202401008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 04/01/2024] [Indexed: 06/14/2024]
Abstract
A challenging task in solid oxide fuel cells (SOFCs) is seeking for an alternative electrolyte, enabling high ionic conduction at relatively low operating temperatures, i.e., 300-600 °C. Proton-conducting candidates, in particular, hold a significant promise due to their low transport activation energy to deliver protons. Here, a unique hierarchical TiO2-SrTiO3@TiO2 structure is developed inside an intercalated TiO2-SrTiO3 core as "yolk" decorating densely packed flake TiO2 as shell, creating plentiful nano-heterointerfaces with a continuous TiO2 and SrTiO3 "in-house" interfaces, as well the interfaces between TiO2-SrTiO3 yolk and TiO2 shell. It exhibits a reduced activation energy, down to 0.225 eV, and an unexpectedly high proton conductivity at low temperature, e.g., 0.084 S cm-1 at 550 °C, confirmed by experimentally H/D isotope method and proton-filtrating membrane measurement. Raman mapping technique identifies the presence of hydrogenated HO─Sr bonds, providing further evidence for proton conduction. And its interfacial conduction is comparatively analyzed with a directly-mixing TiO2-SrTiO3 composite electrolyte. Consequently, a single fuel cell based on the TiO2-SrTiO3@TiO2 heterogeneous electrolyte delivers a good peak power density of 799.7 mW cm-2 at 550 °C. These findings highlight a dexterous nano-heterointerface design strategy of highly proton-conductive electrolytes at reduced operating temperatures for SOFC technology.
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Affiliation(s)
- Mengchen Du
- State Key Laboratory of Metastable Materials Science and Technology (MMST), Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao, 066004, P. R. China
| | - Shaozheng Ji
- Ultrafast Electron Microscopy Laboratory, School of Physics, Nankai University, Tianjin, 300071, China
| | - Pan Zhang
- State Key Laboratory of Metastable Materials Science and Technology (MMST), Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao, 066004, P. R. China
| | - Yongfu Tang
- State Key Laboratory of Metastable Materials Science and Technology (MMST), Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao, 066004, P. R. China
| | - Yanyan Liu
- State Key Laboratory of Metastable Materials Science and Technology (MMST), Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao, 066004, P. R. China
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2
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Guo YD, Meng RJ, Hu XQ, Lin LY, Yang YR, Yang MY, You Y, Zhang LQ, Xu YL, Yan XH. Strain-induced ferroelectric polarization reversal without undergoing geometric inversion in blue SiSe monolayer. Phys Chem Chem Phys 2024; 26:15629-15636. [PMID: 38764382 DOI: 10.1039/d4cp00558a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
Ferroelectricity in two-dimensional (2D) systems generally arises from phonons and has been widely investigated. On the contrary, electronic ferroelectricity in 2D systems has been rarely studied. Using first-principles calculations, the ferroelectric behavior of the buckled blue SiSe monolayer under strain are explored. It is found that the direction of the out-of-plane ferroelectric polarization can be reversed by applying an in-plane strain. And such polarization switching is realized without undergoing geometric inversion. Besides, the strain-triggered polarization reversal emerges in both biaxial and uniaxial strain cases, indicating it is an intrinsic feature of such a system. Further analysis shows that the polarization switching is the result of the reversal of the magnitudes of the positive and negative charge center vectors. And the variation of buckling is found to play an important role, which results in the switch. Moreover, a non-monotonic variation of band gap with strain is revealed. Our findings throws light on the investigation of novel electronic ferroelectric systems.
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Affiliation(s)
- Yan-Dong Guo
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046, China.
- Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing 210023, China
| | - Rui-Jie Meng
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046, China.
| | - Xue-Qin Hu
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046, China.
| | - Li-Yan Lin
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046, China.
| | - Yu-Rong Yang
- National Laboratory of Solid State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, China
- Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210093, China
| | - Ming-Yu Yang
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046, China.
| | - Yun You
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046, China.
| | - Lan-Qi Zhang
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046, China.
| | - Yi-Long Xu
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046, China.
| | - Xiao-Hong Yan
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046, China.
- Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing 210023, China
- College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
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3
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Pathak R, Dutta P, Dolui K, Vasdev A, Ghosh A, Roy RS, Gautam UK, Maji TK, Sheet G, Biswas K. Mild chemistry synthesis of ultrathin Bi 2O 2S nanosheets exhibiting 2D-ferroelectricity at room temperature. Chem Sci 2024; 15:7170-7177. [PMID: 38756816 PMCID: PMC11095514 DOI: 10.1039/d4sc00067f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/07/2024] [Indexed: 05/18/2024] Open
Abstract
Modern technology demands miniaturization of electronic components to build small, light, and portable devices. Hence, discovery and synthesis of new non-toxic, low cost, ultra-thin ferroelectric materials having potential applications in various electronic and optoelectronic devices are of paramount importance. However, achieving room-temperature ferroelectricity in two dimensional (2D) ultra-thin systems remains a major challenge as conventional three-dimensional ferroelectric materials lose their ferroelectricity when the thickness is brought down below a critical value owing to the depolarization field. Herein, we report room-temperature ferroelectricity in ultra-thin single-crystalline 2D nanosheets of Bi2O2S synthesized by a simple, rapid, and scalable solution-based soft chemistry method. The ferroelectric ground state of Bi2O2S nanosheets is confirmed by temperature-dependent dielectric measurements as well as piezoelectric force microscopy and spectroscopy. High resolution transmission electron microscopy analysis and density functional theory-based calculations suggest that the ferroelectricity in Bi2O2S nanosheets arises due to the local distortion of Bi2O2 layers, which destroys the local inversion symmetry of Bi2O2S.
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Affiliation(s)
- Riddhimoy Pathak
- New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
| | - Prabir Dutta
- New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
| | - Kapildeb Dolui
- Department of Materials Science & Metallurgy, University of Cambridge 27 Charles Babbage Road Cambridge CB3 0FS UK
| | - Aastha Vasdev
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli, P.O. Box 140306 India
| | - Adrija Ghosh
- New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
| | - Raj Sekhar Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli, P.O. Box 140306 India
| | - Ujjal K Gautam
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli, P.O. Box 140306 India
| | - Tapas Kumar Maji
- New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
| | - Goutam Sheet
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli, P.O. Box 140306 India
| | - Kanishka Biswas
- New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O. Bangalore 560064 India
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4
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Xu J, Yang Z, Liu W, Wang L, Wang Y. How to enhance the polarization intensity of two-dimensional sliding ferroelectricity for hexagonal boron- or nitrogen-based binary compounds? JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:205505. [PMID: 38346346 DOI: 10.1088/1361-648x/ad2884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Accepted: 02/12/2024] [Indexed: 02/22/2024]
Abstract
In recent years, two-dimensional (2D) sliding ferroelectric (SFE) materials have received widespread attention due to their unique ferroelectric mechanism, which exists in van der Waals bilayer and multilayer systems. However, compared to traditional ferroelectric materials, their relatively weak polarization intensity and low energy barrier limit their practical applications. Here, using the first-principles calculations, we focus on hexagonal layered structures formed by group III-V elements and propose a design principle that utilizes bilayer materials composed of elements with significant differences in atomic electronegativity to address this issue. The results show that materials composed of two atoms with significant electronegativity differences can effectively increase the polarization intensity and possess moderate energy barriers. Furthermore, the polarization intensity can be effectively modulated by adjusting interlayer distance. The research findings have important significance for the exploration of other 2D SFE materials with high polarization intensity.
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Affiliation(s)
- Jinrong Xu
- Key Laboratory of Advanced Electronic Materials and Devices, School of Physics and Mathematics, Anhui Jianzhu University, Hefei 230601, People's Republic of China
| | - Ziyue Yang
- Key Laboratory of Advanced Electronic Materials and Devices, School of Physics and Mathematics, Anhui Jianzhu University, Hefei 230601, People's Republic of China
| | - Wenjing Liu
- Key Laboratory of Advanced Electronic Materials and Devices, School of Physics and Mathematics, Anhui Jianzhu University, Hefei 230601, People's Republic of China
| | - Li Wang
- School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei 230601, People's Republic of China
| | - Ying Wang
- Key Laboratory of Advanced Electronic Materials and Devices, School of Physics and Mathematics, Anhui Jianzhu University, Hefei 230601, People's Republic of China
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5
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Sun H, Gu J, Li Y, Paudel TR, Liu D, Wang J, Zang Y, Gu C, Yang J, Sun W, Gu Z, Tsymbal EY, Liu J, Huang H, Wu D, Nie Y. Prominent Size Effects without a Depolarization Field Observed in Ultrathin Ferroelectric Oxide Membranes. PHYSICAL REVIEW LETTERS 2023; 130:126801. [PMID: 37027865 DOI: 10.1103/physrevlett.130.126801] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 06/28/2022] [Accepted: 02/02/2023] [Indexed: 06/19/2023]
Abstract
The increasing miniaturization of electronics requires a better understanding of material properties at the nanoscale. Many studies have shown that there is a ferroelectric size limit in oxides, below which the ferroelectricity will be strongly suppressed due to the depolarization field, and whether such a limit still exists in the absence of the depolarization field remains unclear. Here, by applying uniaxial strain, we obtain pure in-plane polarized ferroelectricity in ultrathin SrTiO_{3} membranes, providing a clean system with high tunability to explore ferroelectric size effects especially the thickness-dependent ferroelectric instability with no depolarization field. Surprisingly, the domain size, ferroelectric transition temperature, and critical strain for room-temperature ferroelectricity all exhibit significant thickness dependence. These results indicate that the stability of ferroelectricity is suppressed (enhanced) by increasing the surface or bulk ratio (strain), which can be explained by considering the thickness-dependent dipole-dipole interactions within the transverse Ising model. Our study provides new insights into ferroelectric size effects and sheds light on the applications of ferroelectric thin films in nanoelectronics.
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Affiliation(s)
- Haoying Sun
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jiahui Gu
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yongqiang Li
- National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- State Key Laboratory of Laser Interaction with Matter, Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024, China
| | - Tula R Paudel
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68583, USA
- Department of Physics, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701, USA
| | - Di Liu
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China
| | - Jierong Wang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yipeng Zang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- School of Materials Science and Engineering, Anhui University, Hefei 230601, China
| | - Chengyi Gu
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jiangfeng Yang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Wenjie Sun
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Zhengbin Gu
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Evgeny Y Tsymbal
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68583, USA
- Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
| | - Junming Liu
- National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Houbing Huang
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China
| | - Di Wu
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yuefeng Nie
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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6
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Study on Properties of Potassium Sodium Niobate Coating Prepared by High Efficiency Supersonic Plasma Spraying. ACTUATORS 2022. [DOI: 10.3390/act11020028] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
In order to realize the construction of environmentally friendly potassium sodium niobate ceramic coating on metal surface, potassium sodium niobate ceramic coating was prepared by supersonic plasma spraying technology. The morphology, element extension and phase structure of such coating were investigated. The dielectric and ferroelectric properties were also analyzed. The results show that the coating has good quality and tetragonal phase structure. When test frequency ≥ 2 MHz, the dielectric constant is stable at about 300, and also dielectric loss is stable at about 0.05. The coating exhibits good hysteresis loops under different applied electric fields. When the applied electric field is 16 KV/cm, residual polarization value of as-prepared coating reaches 17.02 μC·cm−2.
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7
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Zhang Z, Nie J, Zhang Z, Yuan Y, Fu YS, Zhang W. Atomic Visualization and Switching of Ferroelectric Order in β-In 2 Se 3 Films at the Single Layer Limit. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2106951. [PMID: 34755394 DOI: 10.1002/adma.202106951] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 10/24/2021] [Indexed: 06/13/2023]
Abstract
2D ferroelectrics have received wide interest due to the remarkable quantum states of emerging physics at reduced dimensionality, associated with their exotic properties in high-performance and nonvolatile functional devices. Here, by combing molecular beam epitaxy synthesis and scanning tunneling microscopy characterization, two metastable phases of layered In2 Se3 films: β'- and β*-In2 Se3 are reported, which develop different types of in-plane spontaneous polarizations, thus resulting in different striped morphologies. The anti-ferroelectric order in β'-In2 Se3 and ferroelectric order of β*-In2 Se3 are identified, respectively, down to the 2D limit by comprehensive investigations of structural and spectroscopic signatures, including the lattice distortion, the spatial profile of images, the formation of domain structure, and the electronic band-bending by polarization charges at edges. The ferroelectric switching between those two phases are further controlled via applying an electric field generated from the scanning tunneling microscopy tip in a reversible manner. The intriguing tunability between the (anti-)ferroelectric orders in the 2D limit provides a promising platform for studying the interplay between electronic structure and ferroelectricity in van der Waals materials, and promotes potential development of miniaturized transistors and memory devices based on electric polarizations.
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Affiliation(s)
- Zhimo Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jinhua Nie
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Zhihao Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yuan Yuan
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Ying-Shuang Fu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Wenhao Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
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8
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Guan S, Zhang G, Liu C. Enhanced in-plane ferroelectricity, antiferroelectricity, and unconventional 2D emergent fermions in quadruple-layer XSbO 2 (X = Li, Na). NANOSCALE 2021; 13:19172-19180. [PMID: 34781325 DOI: 10.1039/d1nr06051a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Low-dimensional ferroelectricity and Dirac materials with protected band crossings are fascinating research subjects. Based on first-principles calculations, we predict the coexistence of spontaneous in-plane polarization and novel 2D emergent fermions in dynamically stable quadruple-layer (QL) XSbO2 (X = Li, Na). Depending on the different polarization configurations, QL-XSbO2 can exhibit unconventional inner-QL ferroelectricity and antiferroelectricity. Both ground states harbor robust ferroelectricity with enhanced spontaneous polarization of 0.56 nC m-1 and 0.39 nC m-1 for QL-LiSbO2 and QL-NaSbO2, respectively. Interestingly, the QL-LiSbO2 possesses two other metastable ferroelectric (FE) phases. The ground FE phase can be flexibly driven into one of the two metastable FE phases and then into the antiferroelectric (AFE) phase. During this phase transition, several types of 2D fermions emerge, for instance, hourglass hybrid and type-II Weyl loops in the ground FE phase, type-II Weyl fermionsin the metastable FE phase, and type-II Dirac fermions in the AFE phase. These 2D fermions are robust under spin-orbit coupling. Notably, two of these fermions, e.g., an hourglass hybrid or type-II Weyl loop, have not been observed before. Our findings identify QL-XSbO2 as a unique platform for studying 2D ferroelectricity relating to 2D emergent fermions.
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Affiliation(s)
- Shan Guan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China.
| | - GuangBiao Zhang
- Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, China.
- International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, China
| | - Chang Liu
- Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, China.
- International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, China
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9
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Wang Y, Zhang L, Wang J, Li Q, Wang H, Gu L, Chen J, Deng J, Lin K, Huang L, Xing X. Chemical-Pressure-Modulated BaTiO 3 Thin Films with Large Spontaneous Polarization and High Curie Temperature. J Am Chem Soc 2021; 143:6491-6497. [PMID: 33900066 DOI: 10.1021/jacs.1c00605] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Although BaTiO3 is one of the most famous lead-free piezomaterials, it suffers from small spontaneous and low Curie temperature. Chemical pressure, as a mild way to modulate the structures and properties of materials by element doping, has been utilized to enhance the ferroelectricity of BaTiO3 but is not efficient enough. Here, we report a promoted chemical pressure route to prepare high-performance BaTiO3 films, achieving the highest remanent polarization, Pr (100 μC/cm2), to date and high Curie temperature, Tc (above 1000 °C). The negative chemical pressure (∼-5.7 GPa) was imposed by the coherent lattice strain from large cubic BaO to small tetragonal BaTiO3, generating high tetragonality (c/a = 1.12) and facilitating large displacements of Ti. Such negative pressure is especially significant to the bonding states, i.e., hybridization of Ba 5p-O 2p, whereas ionic bonding in bulk and strong bonding of Ti eg and O 2p, which contribute to the tremendously enhanced polarization. The promoted chemical pressure method shows general potential in improving ferroelectric and other functional materials.
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Affiliation(s)
- Yilin Wang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
- Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Linxing Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Jiaou Wang
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Qiang Li
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Huanhua Wang
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jun Chen
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Jinxia Deng
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Kun Lin
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Ling Huang
- Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Xianran Xing
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China
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10
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Spaldin NA, Efe I, Rossell MD, Gattinoni C. Layer and spontaneous polarizations in perovskite oxides and their interplay in multiferroic bismuth ferrite. J Chem Phys 2021; 154:154702. [PMID: 33887947 DOI: 10.1063/5.0046061] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We review the concept of surface charge, first, in the context of the polarization in ferroelectric materials and, second, in the context of layers of charged ions in ionic insulators. While the former is traditionally discussed in the ferroelectrics community and the latter in the surface science community, we remind the reader that the two descriptions are conveniently unified within the modern theory of polarization. In both cases, the surface charge leads to electrostatic instability-the so-called "polar catastrophe"-if it is not compensated, and we review the range of phenomena that arise as a result of different compensation mechanisms. We illustrate these concepts using the example of the prototypical multiferroic bismuth ferrite, BiFeO3, which is unusual in that its spontaneous ferroelectric polarization and the polarization arising from its layer charges can be of the same magnitude. As a result, for certain combinations of polarization orientation and surface termination, its surface charge is self-compensating. We use density functional calculations of BiFeO3 slabs and superlattices, analysis of high-resolution transmission electron micrographs, and examples from the literature to explore the consequences of this peculiarity.
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Affiliation(s)
- Nicola A Spaldin
- Department of Materials, ETH Zurich, CH-8093 Zürich, Switzerland
| | - Ipek Efe
- Department of Materials, ETH Zurich, CH-8093 Zürich, Switzerland
| | - Marta D Rossell
- Electron Microscopy Center, Swiss Federal Laboratories for Materials Science and Technology, Empa, 8600 Dübendorf, Switzerland
| | - Chiara Gattinoni
- Department of Materials, ETH Zurich, CH-8093 Zürich, Switzerland
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11
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Peters JJP, Bristowe NC, Rusu D, Apachitei G, Beanland R, Alexe M, Sanchez AM. Polarization Screening Mechanisms at La 0.7Sr 0.3MnO 3-PbTiO 3 Interfaces. ACS APPLIED MATERIALS & INTERFACES 2020; 12:10657-10663. [PMID: 32028760 DOI: 10.1021/acsami.9b21619] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The structural, electronic, and magnetic properties of interfaces between epitaxial La0.7Sr0.3MnO3 and PbTiO3 have been explored via atomic resolution transmission electron microscopy of a functional multiferroic tunnel junction. Measurements of the polar displacements and octahedral tilting show the competition between the two distortions at the interface and demonstrate strong dependence on the polarization orientation. The density functional theory provides information on the electronic and magnetic properties, where the interface termination plays a crucial role in the screening mechanisms.
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Affiliation(s)
| | | | - Dorin Rusu
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | | | - Richard Beanland
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | - Marin Alexe
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | - Ana M Sanchez
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
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12
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He C, Zhu J, Zhao YH, Liu C, Fu B. Unconventional inner-TL electric polarization in TL-LaOBiS 2 with ultrahigh carrier mobility. NANOSCALE 2019; 11:18436-18443. [PMID: 31576880 DOI: 10.1039/c9nr05282h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Based on first principles calculations, we propose a new 2D ferroelectric material, triple-layer (TL) LaOBiS2, with an ultrahigh carrier mobility over 40 000 cm2 V-1 s-1 and large sunlight absorption. TL-LaOBiS2 is composed of a middle LaO layer and top-and-bottom BiS2 layers that can be possibly exfoliated from its bulk counterpart. We reveal that each BiS2 layer can hold spontaneous in-plane ferroelectric polarization that can be further enhanced by imposing extensive strain. Furthermore, we discover that TL-LaOBiS2 possesses unconventional inner-TL ferroelectric (FE), antiferroelectric (AFE) and orthogonal polarizations. The ground inner-TL AFE state can be flexibly driven into a nearly degenerate FE state. Moreover, the direct band gaps, optical absorption and the carrier mobilities of TL-LaOBiS2 can be effectively regulated by different ferroelectric polarization configurations. This finding of various ferroelectric states with ultrahigh mobility and excellent optical absorption in TL-LaOBiS2 provides a promising platform for future realization of two-dimensional ferroelectric photovoltaic devices.
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Affiliation(s)
- Chao He
- College of Physics and Electronic Engineering, Center for Computational Sciences, Sichuan Normal University, Chengdu, 610068, China.
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13
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Ghosh T, Samanta M, Vasdev A, Dolui K, Ghatak J, Das T, Sheet G, Biswas K. Ultrathin Free-Standing Nanosheets of Bi 2O 2Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure. NANO LETTERS 2019; 19:5703-5709. [PMID: 31347854 DOI: 10.1021/acs.nanolett.9b02312] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Ultrathin ferroelectric semiconductors with high charge carrier mobility are much coveted systems for the advancement of various electronic and optoelectronic devices. However, in traditional oxide ferroelectric insulators, the ferroelectric transition temperature decreases drastically with decreasing material thickness and ceases to exist below certain critical thickness owing to depolarizing fields. Herein, we show the emergence of an ordered ferroelectric ground state in ultrathin (∼2 nm) single crystalline nanosheets of Bi2O2Se at room temperature. Free-standing ferroelectric nanosheets, in which oppositely charged alternating layers are self-assembled together by electrostatic interactions, are synthesized by a simple, rapid, and scalable wet chemical procedure at room temperature. The existence of ferroelectricity in Bi2O2Se nanosheets is confirmed by dielectric measurements and piezoresponse force spectroscopy. The spontaneous orthorhombic distortion in the ultrathin nanosheets breaks the local inversion symmetry, thereby resulting in ferroelectricity. The local structural distortion and the formation of spontaneous dipole moment were directly probed by atomic resolution scanning transmission electron microscopy and density functional theory calculations.
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Affiliation(s)
- Tanmoy Ghosh
- New Chemistry Unit , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
| | - Manisha Samanta
- New Chemistry Unit , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
| | - Aastha Vasdev
- Department of Physical Sciences , Indian Institute of Science Education and Research Mohali , Sector 81, S. A. S. Nagar, Manauli 140306 , India
| | - Kapildeb Dolui
- Department of Physics and Astronomy , University of Delaware , Newark , Delaware 19716-2570 , United States
| | - Jay Ghatak
- International Centre for Materials Science , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
| | - Tanmoy Das
- Department of Physics , Indian Institute of Science , Bangalore 560012 , India
| | - Goutam Sheet
- Department of Physical Sciences , Indian Institute of Science Education and Research Mohali , Sector 81, S. A. S. Nagar, Manauli 140306 , India
| | - Kanishka Biswas
- New Chemistry Unit , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
- International Centre for Materials Science , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
- School of Advanced Materials , Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur, Bangalore 560064 , India
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14
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Akbarian D, Yilmaz DE, Cao Y, Ganesh P, Dabo I, Munro J, Van Ginhoven R, van Duin ACT. Understanding the influence of defects and surface chemistry on ferroelectric switching: a ReaxFF investigation of BaTiO 3. Phys Chem Chem Phys 2019; 21:18240-18249. [PMID: 31393478 DOI: 10.1039/c9cp02955a] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Ferroelectric materials such as barium titanate (BaTiO3) have a wide range of applications in nano scale electronic devices due to their outstanding properties. In this study, we developed an easily extendable atomistic ReaxFF reactive force field for BaTiO3 that can capture both its field- and temperature-induced ferroelectric hysteresis and corresponding changes due to surface chemistry and bulk defects. Using our force field, we were able to reproduce and explain a number of experimental observations: (1) the existence of a critical thickness of 4.8 nm below which ferroelectricity vanishes in BaTiO3; (2) migration and clustering of oxygen vacancies (OVs) in BaTiO3 and a reduction in the polarization and the Curie temperature due to the OVs; (3) domain wall interaction with the surface chemistry to influence the ferroelectric switching and polarization magnitude. This new computational tool opens up a wide range of possibilities for making predictions for realistic ferroelectric interfaces in energy-conversion, electronic and neuromorphic systems.
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Affiliation(s)
- Dooman Akbarian
- Department of Mechanical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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15
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Direct observation of room-temperature out-of-plane ferroelectricity and tunneling electroresistance at the two-dimensional limit. Nat Commun 2018; 9:3319. [PMID: 30127419 PMCID: PMC6102252 DOI: 10.1038/s41467-018-05662-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 07/02/2018] [Indexed: 02/06/2023] Open
Abstract
Out-of-plane ferroelectricity with a high transition temperature in nanometer-scale films is required to miniaturize electronic devices. Direct visualization of stable ferroelectric polarization and its switching behavior in atomically thick films is critical for achieving this goal. Here, ferroelectric order at room temperature in the two-dimensional limit is demonstrated in tetragonal BiFeO3 ultrathin films. Using aberration-corrected scanning transmission electron microscopy, we directly observed robust out-of-plane spontaneous polarization in one-unit-cell-thick BiFeO3 films. High-resolution piezoresponse force microscopy measurements show that the polarization is stable and switchable, whereas a tunneling electroresistance effect of up to 370% is achieved in BiFeO3 films. Based on first-principles calculations and Kelvin probe force microscopy measurements, we explain the mechanism of polarization stabilization by the ionic displacements in oxide electrode and the surface charges. Our results indicate that critical thickness for ferroelectricity in the BiFeO3 film is virtually absent, making it a promising candidate for high-density nonvolatile memories. High temperature perpendicular ferroelectricity in nano thin films is crucial for miniaturization of electronic devices. Here the authors show the presence of stable and switchable out-of-plane ferroelectricity in tetragonal BiFeO3 thin films at the two-dimensional limit and 370% tunneling electroresistance in ferroelectric tunnel junctions.
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16
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Liu K, Lu J, Picozzi S, Bellaiche L, Xiang H. Intrinsic Origin of Enhancement of Ferroelectricity in SnTe Ultrathin Films. PHYSICAL REVIEW LETTERS 2018; 121:027601. [PMID: 30085752 DOI: 10.1103/physrevlett.121.027601] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Indexed: 06/08/2023]
Abstract
Previous studies showed that, as ferroelectric films become thinner, their Curie temperature (T_{c}) and polarization below T_{c} both typically decrease. In contrast, a recent experiment [Chang et al., Science 353, 274 (2016)SCIEAS0036-807510.1126/science.aad8609] observed that atomic-thick SnTe films have a higher T_{c} than their bulk counterpart, which was attributed to extrinsic effects. We find, using first-principles calculations, that the 0-K energy barrier for the polarization switching (which is a quantity directly related to T_{c}) is higher in most investigated defect-free SnTe ultrathin films than that in bulk SnTe, and that the 5-unit-cell (UC) SnTe thin film has the largest energy barrier as a result of an interplay between hybridization interactions and Pauli repulsions. Further simulations, employing a presently developed effective Hamiltonian, confirm that freestanding, defect-free SnTe thin films have a higher T_{c} than bulk SnTe, except for the 1-UC case. Our work, therefore, demonstrates the possibility to intrinsically enhance ferroelectricity of ultrathin films by reducing their thickness.
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Affiliation(s)
- Kai Liu
- Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
| | - Jinlian Lu
- Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
| | - Silvia Picozzi
- Consiglio Nazionale delle Ricerche, CNR-SPIN, Via dei Vestini 31, Chieti 66100, Italy
| | - Laurent Bellaiche
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Hongjun Xiang
- Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
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17
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De Luca G, Strkalj N, Manz S, Bouillet C, Fiebig M, Trassin M. Nanoscale design of polarization in ultrathin ferroelectric heterostructures. Nat Commun 2017; 8:1419. [PMID: 29127282 PMCID: PMC5681682 DOI: 10.1038/s41467-017-01620-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 10/04/2017] [Indexed: 02/07/2023] Open
Abstract
The success of oxide electronics depends on the ability to design functional properties such as ferroelectricity with atomic accuracy. However, despite tremendous advances in ferroelectric heterostructures, the development towards multilevel architectures with precise layer-by-layer command over the polarization is impeded by the lack of continuous control over the balance of electrostatics, strain, chemistry and film thickness during growth. Moreover, the polarization in the deeper layers becomes inaccessible when these are buried by the ongoing deposition. Taking ferroelectric BaTiO3 and multiferroic BiFeO3 as model systems, we observe and engineer the emergence, orientation and interaction of ferroelectric polarization in ultrathin heterostructures with monolayer accuracy. We achieve this by optical second harmonic generation which tracks the evolution of spontaneous polarization in real time throughout the deposition process. Such direct and in situ access to the polarization during growth leads us to heterostructures with user-defined polarization sequences—towards a new class of functional ferroic materials. Ferroelectric heterostructures exhibit a range of functional properties; however control of their growth remains a challenge. De Luca et al., demonstrate in-situ optical second harmonic generation to monitor and tailor the polarisation and growth of multilayer barium titanate and bismuth ferrite films.
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Affiliation(s)
- Gabriele De Luca
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093, Zurich, Switzerland
| | - Nives Strkalj
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093, Zurich, Switzerland
| | - Sebastian Manz
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093, Zurich, Switzerland
| | - Corinne Bouillet
- Institut de Physique et Chimie des Matériaux de Strasbourg-CNRS UMR 7504, 67034, Strasbourg, France
| | - Manfred Fiebig
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093, Zurich, Switzerland
| | - Morgan Trassin
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093, Zurich, Switzerland.
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18
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Zubko P, Lu H, Bark CW, Martí X, Santiso J, Eom CB, Catalan G, Gruverman A. On the persistence of polar domains in ultrathin ferroelectric capacitors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:284001. [PMID: 28593933 DOI: 10.1088/1361-648x/aa73c3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The instability of ferroelectric ordering in ultra-thin films is one of the most important fundamental issues pertaining realization of a number of electronic devices with enhanced functionality, such as ferroelectric and multiferroic tunnel junctions or ferroelectric field effect transistors. In this paper, we investigate the polarization state of archetypal ultrathin (several nanometres) ferroelectric heterostructures: epitaxial single-crystalline BaTiO3 films sandwiched between the most habitual perovskite electrodes, SrRuO3, on top of the most used perovskite substrate, SrTiO3. We use a combination of piezoresponse force microscopy, dielectric measurements and structural characterization to provide conclusive evidence for the ferroelectric nature of the relaxed polarization state in ultrathin BaTiO3 capacitors. We show that even the high screening efficiency of SrRuO3 electrodes is still insufficient to stabilize polarization in SrRuO3/BaTiO3/SrRuO3 heterostructures at room temperature. We identify the key role of domain wall motion in determining the macroscopic electrical properties of ultrathin capacitors and discuss their dielectric response in the light of the recent interest in negative capacitance behaviour.
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Affiliation(s)
- Pavlo Zubko
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom
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19
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Possible absence of critical thickness and size effect in ultrathin perovskite ferroelectric films. Nat Commun 2017; 8:15549. [PMID: 28585548 PMCID: PMC5467161 DOI: 10.1038/ncomms15549] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 04/07/2017] [Indexed: 11/08/2022] Open
Abstract
Although the size effect in ferroelectric thin films has been known for long time, the underlying mechanism is not yet fully understood and whether or not there is a critical thickness below which the ferroelectricity vanishes is still under debate. Here, we directly measure the thickness-dependent polarization in ultrathin PbZr0.2Ti0.8O3 films via quantitative annular bright field imaging. We find that the polarization is significantly suppressed for films <10-unit cells thick (∼4 nm). However, approximately the polarization never vanishes. The residual polarization is ∼16 μCcm−2 (∼17%) at 1.5-unit cells (∼0.6 nm) thick film on bare SrTiO3 and ∼22 μCcm−2 at 2-unit cells thick film on SrTiO3 with SrRuO3 electrode. The residual polarization in these ultrathin films is mainly attributed to the robust covalent Pb–O bond. Our atomic study provides new insights into mechanistic understanding of nanoscale ferroelectricity and the size effects. Understanding ferroelectricity at reduced dimensions will be important for future sub-nanoscale devices based on ferroelectrics. Using high resolution electron microscopy; Gao et al., observe the existence of a measurable polarization at a thickness of just 1.5-unit cells
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20
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Rajan S, Gazzali PMM, Chandrasekaran G. Impact of Fe on structural modification and room temperature magnetic ordering in BaTiO 3. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 171:80-89. [PMID: 27487577 DOI: 10.1016/j.saa.2016.07.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 07/22/2016] [Accepted: 07/25/2016] [Indexed: 06/06/2023]
Abstract
Ba1-xFexTiO3 (x=0, 0.005, 0.01) polycrystalline ceramics are prepared using solid state reaction method. Structural studies through XRD, Raman and XPS confirm single tetragonal phase for BaTiO3 whereas a structural disorder tends to intervene with the introduction of smaller Fe ions which reduces the tolerance factor and tetragonality ratio. Grain size of the samples is estimated using SEM micrographs with ImageJ software and chemical composition is confirmed using EDX spectra. Raman spectra measured in the temperature range of 303K to 573K showers light on the structural phase transition exploiting a significant disappearance of the 306cm-1 mode. Further, structural analyses suggest the entry of Fe into the B-site upon increasing its concentration in BaTiO3. The dopant sensitive modes lying at around 640cm-1 and 650cm-1 are assigned to lattice strain. A reduction in ferroelectric to paraelectric transition temperature is observed with a transformation from diffused type to normal ferroelectric upon the increased Fe content. The oxidation state of Fe in the BaTiO3 lattice has been decided using EPR Spectra precisely. Room temperature magnetic ordering is observed in Fe substituted BaTiO3 using PPMS. The coexistence of ferroelectric and magnetic ordering is established in the present study for optimized Fe substituted BaTiO3.
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Affiliation(s)
- Soumya Rajan
- Magnetism and Magnetic Materials Laboratory, Department of Physics, Pondicherry University, Pondicherry 605014, India
| | - P M Mohammed Gazzali
- Magnetism and Magnetic Materials Laboratory, Department of Physics, Pondicherry University, Pondicherry 605014, India
| | - G Chandrasekaran
- Magnetism and Magnetic Materials Laboratory, Department of Physics, Pondicherry University, Pondicherry 605014, India.
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21
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Wang Y, Zhao H, Zhang L, Chen J, Xing X. PbTiO3-based perovskite ferroelectric and multiferroic thin films. Phys Chem Chem Phys 2017; 19:17493-17515. [DOI: 10.1039/c7cp01347g] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ferroelectric thin films, especially PbTiO3-based perovskite thin films which possess robust spontaneous electrical polarization, are widely investigated and applied in various devices.
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Affiliation(s)
- Yilin Wang
- Department of Physical Chemistry
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Hanqing Zhao
- Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province
- Taiyuan University of Technology
- China
| | - Linxing Zhang
- Department of Physical Chemistry
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Jun Chen
- Department of Physical Chemistry
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Xianran Xing
- Department of Physical Chemistry
- University of Science and Technology Beijing
- Beijing 100083
- China
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22
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Chang K, Liu J, Lin H, Wang N, Zhao K, Zhang A, Jin F, Zhong Y, Hu X, Duan W, Zhang Q, Fu L, Xue QK, Chen X, Ji SH. Discovery of robust in-plane ferroelectricity in atomic-thick SnTe. Science 2016; 353:274-8. [DOI: 10.1126/science.aad8609] [Citation(s) in RCA: 502] [Impact Index Per Article: 62.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 06/16/2016] [Indexed: 01/18/2023]
Affiliation(s)
- Kai Chang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Junwei Liu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Haicheng Lin
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Na Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Kun Zhao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Anmin Zhang
- Department of Physics, Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Renmin University of China, Beijing 100872, China
| | - Feng Jin
- Department of Physics, Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Renmin University of China, Beijing 100872, China
| | - Yong Zhong
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Xiaopeng Hu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Wenhui Duan
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Qingming Zhang
- Department of Physics, Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Renmin University of China, Beijing 100872, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Xi Chen
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Shuai-Hua Ji
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
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Ferroelectricity and Self-Polarization in Ultrathin Relaxor Ferroelectric Films. Sci Rep 2016; 6:19965. [PMID: 26817516 PMCID: PMC4730210 DOI: 10.1038/srep19965] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 12/08/2015] [Indexed: 12/02/2022] Open
Abstract
We report ferroelectricity and self-polarization in the (001) oriented ultrathin relaxor ferroelectric PMN-PT films grown on Nb-SrTiO3, SrRuO3 and La0.7Sr0.3MnO3, respectively. Resistance-voltage measurements and AC impedance analysis suggest that at high temperatures Schottky depletion width in a 4 nm thick PMN-PT film deposited on Nb-SrTiO3 is smaller than the film thickness. We propose that Schottky interfacial dipoles make the dipoles of the nanometer-sized polar nanoregions (PNRs) in PMN-PT films grown on Nb-SrTiO3 point downward at high temperatures and lead to the self-polarization at room temperature with the assistance of in-plane compressive strain. This work sheds light on the understanding of epitaxial strain effects on relaxor ferroelectric films and self-polarization mechanism.
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24
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Bein B, Hsing HC, Callori SJ, Sinsheimer J, Chinta PV, Headrick RL, Dawber M. In situ X-ray diffraction and the evolution of polarization during the growth of ferroelectric superlattices. Nat Commun 2015; 6:10136. [PMID: 26634894 PMCID: PMC4686826 DOI: 10.1038/ncomms10136] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 11/06/2015] [Indexed: 11/25/2022] Open
Abstract
In epitaxially strained ferroelectric thin films and superlattices, the ferroelectric transition temperature can lie above the growth temperature. Ferroelectric polarization and domains should then evolve during the growth of a sample, and electrostatic boundary conditions may play an important role. In this work, ferroelectric domains, surface termination, average lattice parameter and bilayer thickness are simultaneously monitored using in situ synchrotron X-ray diffraction during the growth of BaTiO3/SrTiO3 superlattices on SrTiO3 substrates by off-axis radio frequency magnetron sputtering. The technique used allows for scan times substantially faster than the growth of a single layer of material. Effects of electric boundary conditions are investigated by growing the same superlattice alternatively on SrTiO3 substrates and 20 nm SrRuO3 thin films on SrTiO3 substrates. These experiments provide important insights into the formation and evolution of ferroelectric domains when the sample is ferroelectric during the growth process.
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Affiliation(s)
- Benjamin Bein
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | - Hsiang-Chun Hsing
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | - Sara J. Callori
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | - John Sinsheimer
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | - Priya V. Chinta
- Department of Physics, Cook Physical Science Building, University of Vermont, Burlington, Vermont 05405, USA
| | - Randall L. Headrick
- Department of Physics, Cook Physical Science Building, University of Vermont, Burlington, Vermont 05405, USA
| | - Matthew Dawber
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
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Abstract
The quest for solid state non-volatility memory devices on silicon with high storage density, high speed, low power consumption has attracted intense research on new materials and novel device architectures. Although flash memory dominates in the non-volatile memory market currently, it has drawbacks, such as low operation speed, and limited cycle endurance, which prevents it from becoming the “universal memory”. In this report, we demonstrate ferroelectric tunnel junctions (Pt/BaTiO3/La0.67Sr0.33MnO3) epitaxially grown on silicon substrates. X-ray diffraction spectra and high resolution transmission electron microscope images prove the high epitaxial quality of the single crystal perovskite films grown on silicon. Furthermore, the write speed, data retention and fatigue properties of the device compare favorably with flash memories. The results prove that the silicon-based ferroelectric tunnel junction is a very promising candidate for application in future non-volatile memories.
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Dubourdieu C, Bruley J, Arruda TM, Posadas A, Jordan-Sweet J, Frank MM, Cartier E, Frank DJ, Kalinin SV, Demkov AA, Narayanan V. Switching of ferroelectric polarization in epitaxial BaTiO₃ films on silicon without a conducting bottom electrode. NATURE NANOTECHNOLOGY 2013; 8:748-54. [PMID: 24077030 DOI: 10.1038/nnano.2013.192] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 08/27/2013] [Indexed: 05/14/2023]
Abstract
Epitaxial growth of SrTiO₃ on silicon by molecular beam epitaxy has opened up the route to the integration of functional complex oxides on a silicon platform. Chief among them is ferroelectric functionality using perovskite oxides such as BaTiO₃. However, it has remained a challenge to achieve ferroelectricity in epitaxial BaTiO₃ films with a polarization pointing perpendicular to the silicon substrate without a conducting bottom electrode. Here, we demonstrate ferroelectricity in such stacks. Synchrotron X-ray diffraction and high-resolution scanning transmission electron microscopy reveal the presence of crystalline domains with the long axis of the tetragonal structure oriented perpendicular to the substrate. Using piezoforce microscopy, polar domains can be written and read and are reversibly switched with a phase change of 180°. Open, saturated hysteresis loops are recorded. Thus, ferroelectric switching of 8- to 40-nm-thick BaTiO₃ films in metal-ferroelectric-semiconductor structures is realized, and field-effect devices using this epitaxial oxide stack can be envisaged.
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Affiliation(s)
- Catherine Dubourdieu
- 1] IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598, USA [2]
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27
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Lu H, Liu X, Burton JD, Bark CW, Wang Y, Zhang Y, Kim DJ, Stamm A, Lukashev P, Felker DA, Folkman CM, Gao P, Rzchowski MS, Pan XQ, Eom CB, Tsymbal EY, Gruverman A. Enhancement of ferroelectric polarization stability by interface engineering. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:1209-1216. [PMID: 22278910 DOI: 10.1002/adma.201104398] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 12/23/2011] [Indexed: 05/31/2023]
Abstract
By using theoretical predictions based on first-principle calculations, we explore an interface engineering approach to stabilize polarization states in ferroelectric heterostructures with a thickness of just several nanometers.
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Affiliation(s)
- H Lu
- Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588, USA
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28
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Kathan-Galipeau K, Wu P, Li Y, Chen LQ, Soukiassian A, Xi X, Schlom DG, Bonnell DA. Quantification of internal electric fields and local polarization in ferroelectric superlattices. ACS NANO 2011; 5:640-646. [PMID: 21162539 DOI: 10.1021/nn102884s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Oxide heterostructure superlattices constitute a new family of materials with tunable ferroelectric properties. While theoretical models predict the presence of nanosized ferroelectric domains in these films, they had not been observed as the magnitude of the response functions challenges the limits of experimental detection. Here, a new protocol in a precise variant of piezoforce microscopy is used to image domains in BaTiO(3)/SrTiO(3) superlattices. Comparison of experimentally determined polarization to predictions of phase-field calculations is in quantitative agreement. Additionally, a combination of theory and experiment is used to determine the magnitude of internal electric field within the thin film, in a procedure that can be generalized to all ferroelectric films.
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Affiliation(s)
- Kendra Kathan-Galipeau
- Department of Materials Science, The University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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29
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Tyunina M, Narkilahti J, Plekh M, Oja R, Nieminen RM, Dejneka A, Trepakov V. Evidence for strain-induced ferroelectric order in epitaxial thin-film KTaO3. PHYSICAL REVIEW LETTERS 2010; 104:227601. [PMID: 20867203 DOI: 10.1103/physrevlett.104.227601] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2010] [Indexed: 05/29/2023]
Abstract
In perovskite-structure epitaxial films, it has been theoretically predicted that the polarization and the coherence of polar order can increase with increasing crystallographic strain. Experimental evidence of strain-induced long-range ferroelectric order has not been obtained thus far, posing the fundamental question of whether or not strain can induce the long-range polar order. Here we demonstrate the existence of strain-induced ferroelectric order in quantum paraelectric KTaO3 by combining experimental investigations of epitaxial KTaO3 films and density-functional-theory calculations. The long-range ferroelectric order does exist under a large enough epitaxial strain. We suggest that a region of short-range polar order might appear between paraelectric and ferroelectric states in the strain-temperature phase diagrams.
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Affiliation(s)
- M Tyunina
- Microelectronics and Materials Physics Laboratories, University of Oulu, P.O. Box 4500, FI-90014 Oulun yliopisto, Finland
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