1
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Xu T, Wu C, Zheng S, Wang Y, Wang J, Hirakata H, Kitamura T, Shimada T. Mechanical Rippling for Diverse Ferroelectric Topologies in Otherwise Nonferroelectric SrTiO_{3} Nanofilms. PHYSICAL REVIEW LETTERS 2024; 132:086801. [PMID: 38457703 DOI: 10.1103/physrevlett.132.086801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 12/18/2023] [Accepted: 01/12/2024] [Indexed: 03/10/2024]
Abstract
Polar topological structures such as skyrmions and merons have become an emerging research field due to their rich functionalities and promising applications in information storage. Up to now, the obtained polar topological structures are restricted to a few limited ferroelectrics with complex heterostructures, limiting their large-scale practical applications. Here, we circumvent this limitation by utilizing a nanoscale ripple-generated flexoelectric field as a universal means to create rich polar topological configurations in nonpolar nanofilms in a controllable fashion. Our extensive phase-field simulations show that a rippled SrTiO_{3} nanofilm with a single bulge activates polarizations that are stabilized in meron configurations, which further undergo topological transitions to Néel-type and Bloch-type skyrmions upon varying the geometries. The formation of these topologies originates from the curvature-dependent flexoelectric field, which extends beyond the common mechanism of geometric confinement that requires harsh energy conditions and strict temperature ranges. We further demonstrate that the rippled nanofilm with three-dimensional ripple patterns can accommodate other unreported modulated phases of ferroelectric topologies, which provide ferroelectric analogs to the complex spin topologies in magnets. The present study not only unveils the intriguing nanoscale electromechanical properties but also opens exciting opportunities to design various functional topological phenomena in flexible materials.
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Affiliation(s)
- Tao Xu
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Chengsheng Wu
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Sizheng Zheng
- Department of Engineering Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, China
| | - Yu Wang
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Jie Wang
- Department of Engineering Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, China
- Zhejiang Laboratory, Hangzhou 311100, Zhejiang, China
| | - Hiroyuki Hirakata
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Takayuki Kitamura
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Takahiro Shimada
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
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2
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Gao Z, Zhang Y, Li X, Zhang X, Chen X, Du G, Hou F, Gu B, Lun Y, Zhao Y, Zhao Y, Qu Z, Jin K, Wang X, Chen Y, Liu Z, Huang H, Gao P, Mostovoy M, Hong J, Cheong SW, Wang X. Mechanical manipulation for ordered topological defects. SCIENCE ADVANCES 2024; 10:eadi5894. [PMID: 38170776 PMCID: PMC10796077 DOI: 10.1126/sciadv.adi5894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 12/01/2023] [Indexed: 01/05/2024]
Abstract
Randomly distributed topological defects created during the spontaneous symmetry breaking are the fingerprints to trace the evolution of symmetry, range of interaction, and order parameters in condensed matter systems. However, the effective mean to manipulate topological defects into ordered form is elusive due to the topological protection. Here, we establish a strategy to effectively align the topological domain networks in hexagonal manganites through a mechanical approach. It is found that the nanoindentation strain gives rise to a threefold Magnus-type force distribution, leading to a sixfold symmetric domain pattern by driving the vortex and antivortex in opposite directions. On the basis of this rationale, sizeable mono-chirality topological stripe is readily achieved by expanding the nanoindentation to scratch, directly transferring the randomly distributed topological defects into an ordered form. This discovery provides a mechanical strategy to manipulate topological protected domains not only on ferroelectrics but also on ferromagnets/antiferromagnets and ferroelastics.
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Affiliation(s)
- Ziyan Gao
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Yixuan Zhang
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Xiaomei Li
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Xiangping Zhang
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Xue Chen
- Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Guoshuai Du
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China
| | - Fei Hou
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China
| | - Baijun Gu
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Yingzhuo Lun
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Yao Zhao
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Yingtao Zhao
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Zhaoliang Qu
- Institute of Advanced Structure Technology, Beijing Institute of Technology, Beijing 100081, China
| | - Ke Jin
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China
| | - Xiaolei Wang
- Department of Physics and Optoelectronics, Faculty of Science, Beijing University of Technology, Beijing 100124, China
| | - Yabin Chen
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China
| | - Zhanwei Liu
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Houbing Huang
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China
| | - Peng Gao
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Maxim Mostovoy
- Zernile Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands
| | - Jiawang Hong
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Sang-Wook Cheong
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854, USA
| | - Xueyun Wang
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
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3
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Kwon YJ, Yeo Y, Kim MS, Kim YJ, Park HS, Kim J, Choi SY, Yang CH. Observation of Hidden Polar Phases and Flux Closure Domain Topology in Bi 2WO 6 Thin Films. NANO LETTERS 2023; 23:4557-4563. [PMID: 37154863 DOI: 10.1021/acs.nanolett.3c01009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Topological textures of ferroelectric polarizations have promise as alternative devices for future information technology. A polarization rotation inevitably deviates from the stable orientation in axial ferroelectrics, but local energy losses compromise the global symmetry, resulting in a distorted shape of the topological vortex or inhibiting the vortex. Easy planar isotropy helps to promote rotating structures and, accordingly, to facilitate access to nontrivial textures. Here, we investigate the domain structure of an epitaxial thin film of bismuth tungsten oxide (Bi2WO6) grown on a (001) SrTiO3 substrate. By using angle-resolved piezoresponse force microscopy and scanning transmission electron microscopy, we find the existence of a hidden phase with ⟨100⟩-oriented ferroelectric polarizations in the middle of the four variant ⟨110⟩-oriented polarization domains, which assists in the formation of flux closure domains. The results suggest that this material is one step closer to becoming an isotropic two-dimensional polar material.
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Affiliation(s)
- Yong-Jun Kwon
- Department of Physics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Youngki Yeo
- Department of Physics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Min-Su Kim
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Yong-Jin Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Heung-Sik Park
- Department of Physics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Jaegyu Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Si-Young Choi
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Department of Semiconductor Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Center of van der Waals Quantum Solids, Institute for Basic Science, Pohang 37673, Republic of Korea
| | - Chan-Ho Yang
- Department of Physics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 34141, Republic of Korea
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4
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Li YQ, Wang P, Zhang H, Zhang H, Fu LB. Nonabelian Ginzburg-Landau theory for ferroelectrics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:155702. [PMID: 36731170 DOI: 10.1088/1361-648x/acb89d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
The Ginzburg-Landau theory, which was introduced to phenomenologically describe the destruction of superconductivity by a magnetic field at the beginning, has brought up much more knowledge beyond the original one as a mean-field theory of thermodynamics states. There the complex order parameter plays an important role. Here we propose a macroscopic theory to describe the features of ferroelectrics by a two-component complex order parameter coupled to nonabelian gauge potentials that provide more freedom to reflect interplays between different measurables. Within this theoretical framework, some recently discovered empirical static and time-independent phenomena, such as vortex, anti-vortex, spiral orders can be obtained as solutions for different gauge potentials. It is expected to bring in a new angle of view with more elucidation than the traditional one that takes the polarization as order parameter.
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Affiliation(s)
- You-Quan Li
- Chern Institute of Mathematics, Nankai University, Weijin Road 94, Tianjin 300071, People's Republic of China
- School of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210008, People's Republic of China
| | - Pei Wang
- Department of Physics, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Hua Zhang
- Center for Advanced Material Diagnostic Technology, Shenzhen Technology University, Shenzhen 518118, People's Republic of China
| | - Hong Zhang
- School of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Li-Bin Fu
- Graduate School of China Academy of Engineering Physics, Beijing 100193, People's Republic of China
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5
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Geng WR, Guo X, Ge HL, Tang YL, Zhu Y, Wang Y, Wu B, Zou MJ, Feng YP, Ma XL. Real-Time Transformation of Flux-Closure Domains with Superhigh Thermal Stability. NANO LETTERS 2022; 22:8892-8899. [PMID: 36331549 DOI: 10.1021/acs.nanolett.2c02969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Polar topologies have received extensive attention due to their exotic configurations and functionalities. Understanding their responsive behaviors to external stimuli, especially thermal excitation, is highly desirable to extend their applications to high temperature, which is still unclear. Here, combining in situ transmission electron microscopy and phase-field simulations, the thermal dynamics of the flux-closure domains were illuminated in PbTiO3/SrTiO3 multilayers. In-depth analyses suggested that the topological transition processes from a/c domains to flux-closure quadrants were influenced by the boundary conditions of PbTiO3 layers. The symmetrical boundary condition stabilized the flux-closure domains at higher temperature than in the asymmetrical case. Furthermore, the reversible thermal responsive behaviors of the flux-closure domains displayed superior thermal stability, which maintained robust up to 450 °C (near the Curie temperature). This work provides new insights into the dynamics of polar topologies under thermal excitation and facilitates their applications as nanoelectronics under extreme conditions.
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Affiliation(s)
- Wan-Rong Geng
- Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, Guangdong523808, People's Republic of China
- Institute of Physics, Chinese Academy of Sciences, Beijing100190, People's Republic of China
| | - Xiangwei Guo
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016Shenyang, People's Republic of China
| | - Hua-Long Ge
- School of Materials and Energy, Yunnan University, Kunming, 650091, People's Republic of China
| | - Yun-Long Tang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016Shenyang, People's Republic of China
| | - Yinlian Zhu
- Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, Guangdong523808, People's Republic of China
| | - Yujia Wang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016Shenyang, People's Republic of China
| | - Bo Wu
- Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, Guangdong523808, People's Republic of China
| | - Min-Jie Zou
- Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, Guangdong523808, People's Republic of China
- Institute of Physics, Chinese Academy of Sciences, Beijing100190, People's Republic of China
| | - Yan-Peng Feng
- Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, Guangdong523808, People's Republic of China
- Institute of Physics, Chinese Academy of Sciences, Beijing100190, People's Republic of China
| | - Xiu-Liang Ma
- Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, Guangdong523808, People's Republic of China
- Institute of Physics, Chinese Academy of Sciences, Beijing100190, People's Republic of China
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6
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Li M, Yang T, Chen P, Wang Y, Zhu R, Li X, Shi R, Liu HJ, Huang YL, Ma X, Zhang J, Bai X, Chen LQ, Chu YH, Gao P. Electric-field control of the nucleation and motion of isolated three-fold polar vertices. Nat Commun 2022; 13:6340. [PMID: 36284138 PMCID: PMC9596422 DOI: 10.1038/s41467-022-33973-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 10/10/2022] [Indexed: 11/21/2022] Open
Abstract
Recently various topological polar structures have been discovered in oxide thin films. Despite the increasing evidence of their switchability under electrical and/or mechanical fields, the dynamic property of isolated ones, which is usually required for applications such as data storage, is still absent. Here, we show the controlled nucleation and motion of isolated three-fold vertices under an applied electric field. At the PbTiO3/SrRuO3 interface, a two-unit-cell thick SrTiO3 layer provides electrical boundary conditions for the formation of three-fold vertices. Utilizing the SrTiO3 layer and in situ electrical testing system, we find that isolated three-fold vertices can move in a controllable and reversible manner with a velocity up to ~629 nm s-1. Microstructural evolution of the nucleation and propagation of isolated three-fold vertices is further revealed by phase-field simulations. This work demonstrates the ability to electrically manipulate isolated three-fold vertices, shedding light on the dynamic property of isolated topological polar structures.
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Affiliation(s)
- Mingqiang Li
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
- Department of Materials Science and Engineering, University of Toronto, Toronto, ON, M5S 3E4, Canada
| | - Tiannan Yang
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Pan Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
| | - Yongjun Wang
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC
| | - Ruixue Zhu
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - Xiaomei Li
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - Ruochen Shi
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - Heng-Jui Liu
- Department of Materials Science and Engineering, National Chung Hsing University, Taichung, 40227, Taiwan, ROC
| | - Yen-Lin Huang
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC
| | - Xiumei Ma
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - Jingmin Zhang
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - Xuedong Bai
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
- School of Physical Sciences, University of Chinese Academy of Sciences, 100190, Beijing, China
- Songshan Lake Materials Laboratory, 523808, Dongguan, Guangdong, China
| | - Long-Qing Chen
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Ying-Hao Chu
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC
- Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan, ROC
| | - Peng Gao
- Electron Microscopy Laboratory, and International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China.
- Collaborative Innovation Centre of Quantum Matter, 100871, Beijing, China.
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, 100871, Beijing, China.
- Hefei National Laboratory, 230088, Hefei, China.
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7
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Guo X, Zhou L, Roul B, Wu Y, Huang Y, Das S, Hong Z. Theoretical Understanding of Polar Topological Phase Transitions in Functional Oxide Heterostructures: A Review. SMALL METHODS 2022; 6:e2200486. [PMID: 35900067 DOI: 10.1002/smtd.202200486] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/15/2022] [Indexed: 06/15/2023]
Abstract
The exotic topological phase is attracting considerable attention in condensed matter physics and materials science over the past few decades due to intriguing physical insights. As a combination of "topology" and "ferroelectricity," the ferroelectric (polar) topological structures are a fertile playground for emergent phenomena and functionalities with various potential applications. Herein, the review starts with the universal concept of the polar topological phase and goes on to briefly discuss the important role of computational tools such as phase-field simulations in designing polar topological phases in oxide heterostructures. In particular, the history of the development of phase-field simulations for ferroelectric oxide heterostructures is highlighted. Then, the current research progress of polar topological phases and their emergent phenomena in ferroelectric functional oxide heterostructures is reviewed from a theoretical perspective, including the topological polar structures, the establishment of phase diagrams, their switching kinetics and interconnections, phonon dynamics, and various macroscopic properties. Finally, this review offers a perspective on the future directions for the discovery of novel topological phases in other ferroelectric systems and device design for next-generation electronic device applications.
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Affiliation(s)
- Xiangwei Guo
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, China
- Institute of Advanced Semiconductors and Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices, Hangzhou Innovation Center, Zhejiang University, Hangzhou, Zhejiang, 311200, China
- Cyrus Tang Center for Sensor Materials and Applications, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, 310027, China
| | - Linming Zhou
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, China
| | - Basanta Roul
- Materials Research Centre, Indian Institute of Science, Bangalore, 560012, India
- Central Research Laboratory, Bharat Electronics Limited, Bangalore, 560013, India
| | - Yongjun Wu
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, China
- Cyrus Tang Center for Sensor Materials and Applications, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, 310027, China
| | - Yuhui Huang
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, China
| | - Sujit Das
- Materials Research Centre, Indian Institute of Science, Bangalore, 560012, India
| | - Zijian Hong
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, China
- Cyrus Tang Center for Sensor Materials and Applications, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, 310027, China
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8
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Chiral structures of electric polarization vectors quantified by X-ray resonant scattering. Nat Commun 2022; 13:1769. [PMID: 35383159 PMCID: PMC8983710 DOI: 10.1038/s41467-022-29359-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Accepted: 03/07/2022] [Indexed: 11/08/2022] Open
Abstract
Resonant elastic X-ray scattering (REXS) offers a unique tool to investigate solid-state systems providing spatial knowledge from diffraction combined with electronic information through the enhanced absorption process, allowing the probing of magnetic, charge, spin, and orbital degrees of spatial order together with electronic structure. A new promising application of REXS is to elucidate the chiral structure of electrical polarization emergent in a ferroelectric oxide superlattice in which the polarization vectors in the REXS amplitude are implicitly described through an anisotropic tensor corresponding to the quadrupole moment. Here, we present a detailed theoretical framework and analysis to quantitatively analyze the experimental results of Ti L-edge REXS of a polar vortex array formed in a PbTiO3/SrTiO3 superlattice. Based on this theoretical framework, REXS for polar chiral structures can become a useful tool similar to x-ray resonant magnetic scattering (XRMS), enabling a comprehensive study of both electric and magnetic REXS on the chiral structures. The polar chiral texture of the vortex or skyrmion structure in ferroelectric oxide PbTiO3/SrTiO3 superlattice attracts attention. Here, the authors report a theoretical framework to probe emergent chirality of electrical polarization textures.
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9
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O'Connell EN, Moore K, McFall E, Hennessy M, Moynihan E, Bangert U, Conroy M. TopoTEM: A Python Package for Quantifying and Visualizing Scanning Transmission Electron Microscopy Data of Polar Topologies. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:1-9. [PMID: 35318910 DOI: 10.1017/s1431927622000435] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The exotic internal structure of polar topologies in multiferroic materials offers a rich landscape for materials science research. As the spatial scale of these entities is often subatomic in nature, aberration-corrected transmission electron microscopy (TEM) is the ideal characterization technique. Software to quantify and visualize the slight shifts in atomic placement within unit cells is of paramount importance due to the now routine acquisition of images at such resolution. In the previous ~decade since the commercialization of aberration-corrected TEM, many research groups have written their own code to visualize these polar entities. More recently, open-access Python packages have been developed for the purpose of TEM atomic position quantification. Building on these packages, we introduce the TEMUL Toolkit: a Python package for analysis and visualization of atomic resolution images. Here, we focus specifically on the TopoTEM module of the toolkit where we show an easy to follow, streamlined version of calculating the atomic displacements relative to the surrounding lattice and thus plotting polarization. We hope this toolkit will benefit the rapidly expanding field of topology-based nano-electronic and quantum materials research, and we invite the electron microscopy community to contribute to this open-access project.
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Affiliation(s)
- Eoghan N O'Connell
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - Kalani Moore
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - Elora McFall
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - Michael Hennessy
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - Eoin Moynihan
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - Ursel Bangert
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - Michele Conroy
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
- Department of Materials, Faculty of Engineering, London Centre of Nanotechnology, Imperial College London, London, UK
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10
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Moore K, O’Connell EN, Griffin SM, Downing C, Colfer L, Schmidt M, Nicolosi V, Bangert U, Keeney L, Conroy M. Charged Domain Wall and Polar Vortex Topologies in a Room-Temperature Magnetoelectric Multiferroic Thin Film. ACS APPLIED MATERIALS & INTERFACES 2022; 14:5525-5536. [PMID: 35044754 PMCID: PMC8815039 DOI: 10.1021/acsami.1c17383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 01/09/2022] [Indexed: 06/14/2023]
Abstract
Multiferroic topologies are an emerging solution for future low-power magnetic nanoelectronics due to their combined tuneable functionality and mobility. Here, we show that in addition to being magnetoelectric multiferroic at room temperature, thin-film Aurivillius phase Bi6TixFeyMnzO18 is an ideal material platform for both domain wall and vortex topology-based nanoelectronic devices. Utilizing atomic-resolution electron microscopy, we reveal the presence and structure of 180°-type charged head-to-head and tail-to-tail domain walls passing throughout the thin film. Theoretical calculations confirm the subunit cell cation site preference and charged domain wall energetics for Bi6TixFeyMnzO18. Finally, we show that polar vortex-type topologies also form at out-of-phase boundaries of stacking faults when internal strain and electrostatic energy gradients are altered. This study could pave the way for controlled polar vortex topology formation via strain engineering in other multiferroic thin films. Moreover, these results confirm that the subunit cell topological features play an important role in controlling the charge and spin state of Aurivillius phase films and other multiferroic heterostructures.
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Affiliation(s)
- Kalani Moore
- Department
of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick V94 T9PX, Ireland
| | - Eoghan N. O’Connell
- Department
of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick V94 T9PX, Ireland
| | - Sinéad M. Griffin
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Clive Downing
- Advanced
Microscopy Laboratory & AMBER, Trinity
College Dublin, Dublin D02 PN40, Ireland
| | - Louise Colfer
- Tyndall
National Institute, University College Cork, Cork T12 R5CP, Ireland
| | - Michael Schmidt
- Tyndall
National Institute, University College Cork, Cork T12 R5CP, Ireland
| | - Valeria Nicolosi
- Advanced
Microscopy Laboratory & AMBER, Trinity
College Dublin, Dublin D02 PN40, Ireland
- School of
Chemistry, Trinity College Dublin, Dublin D02 PN40, Ireland
| | - Ursel Bangert
- Department
of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick V94 T9PX, Ireland
| | - Lynette Keeney
- Tyndall
National Institute, University College Cork, Cork T12 R5CP, Ireland
| | - Michele Conroy
- Department
of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick V94 T9PX, Ireland
- Department
of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, U.K.
- London
Centre for Nanotechnology, Imperial College
London, Exhibition Road, London SW7 2AZ, U.K.
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11
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Baker JS, Bowler DR. Origin of Ferroelectric Domain Wall Alignment with Surface Trenches in Ultrathin Films. PHYSICAL REVIEW LETTERS 2021; 127:247601. [PMID: 34951802 DOI: 10.1103/physrevlett.127.247601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 10/28/2021] [Indexed: 06/14/2023]
Abstract
Engraving trenches on the surfaces of ultrathin ferroelectric (FE) films and superlattices promises control over the orientation and direction of FE domain walls (DWs). Through exploiting the phenomenon of DW-surface trench (ST) parallel alignment, systems where DWs are known for becoming electrical conductors could now become useful nanocircuits using only standard lithographical techniques. Despite this clear application, the microscopic mechanism responsible for the alignment phenomenon has remained elusive. Using ultrathin PbTiO_{3} films as a model system, we explore this mechanism with large scale density functional theory simulations on as many as 5,136 atoms. Although we expect multiple contributing factors, we show that parallel DW-ST alignment can be well explained by this configuration giving rise to an arrangement of electric dipole moments which best restore polar continuity to the film. These moments preserve the polar texture of the pristine film, thus minimizing ST-induced depolarizing fields. Given the generality of this mechanism, we suggest that STs could be used to engineer other exotic polar textures in a variety of FE nanostructures as supported by the appearance of ST-induced polar cycloidal modulations in this Letter. Our simulations also support experimental observations of ST-induced negative strains which have been suggested to play a role in the alignment mechanism.
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Affiliation(s)
- Jack S Baker
- London Centre for Nanotechnology, University College London, 17-19 Gordon St, London WC1H 0AH, United Kingdom
- Department of Physics & Astronomy, University College London, Gower St, London WC1E 6BT, United Kingdom
| | - David R Bowler
- London Centre for Nanotechnology, University College London, 17-19 Gordon St, London WC1H 0AH, United Kingdom
- Department of Physics & Astronomy, University College London, Gower St, London WC1E 6BT, United Kingdom
- International Centre for Materials Nanoarchitectonics (MANA) National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
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12
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Geng W, Wang Y, Tang Y, Zhu Y, Wu B, Yang L, Feng Y, Zou M, Ma X. Atomic-Scale Tunable Flexoelectric Couplings in Oxide Multiferroics. NANO LETTERS 2021; 21:9601-9608. [PMID: 34766784 DOI: 10.1021/acs.nanolett.1c03352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Flexoelectricity is an effective tool in modulating the crystallographic structures and properties of oxides for multifunctional applications. However, engineering the nonuniform strain to obtain tunable flexoelectric behaviors at the atomic scale remains an ongoing challenge in conventional substrate-imposed ferroelectric films. Here, the regulatable flexoelectric behaviors are demonstrated at atomic scale in [110]-oriented BiFeO3 thin films, which are triggered by the strain-field coupling of high-density interfacial dislocations. Using aberration-corrected scanning transmission electron microscopy, the asymmetric polarization rotation around the single dislocation is revealed, which is induced by the gradient strain fields of the single dislocation. These strain fields are highly correlated to generate huge strain gradients between neighboring dislocations, and thereby, serial flexoelectric responses are engineered as a function of dislocation spacings in thicker BiFeO3 films. This work opens a pathway for the modulation of flexoelectric responses in ferroelectrics, which could be extended to other functional materials to create exotic phenomena.
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Affiliation(s)
- Wanrong Geng
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yujia Wang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016 Shenyang, China
| | - Yunlong Tang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016 Shenyang, China
| | - Yinlian Zhu
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016 Shenyang, China
| | - Bo Wu
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Lixin Yang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016 Shenyang, China
| | - Yanpeng Feng
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Minjie Zou
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiuliang Ma
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016 Shenyang, China
- State Key Lab of Advanced Processing and Recycling on Non-ferrous Metals, Lanzhou University of Technology, Langongping Road 287, 730050 Lanzhou, China
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