1
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Eggestad K, Williamson BAD, Meier D, Selbach SM. Mobile intrinsic point defects for conductive neutral domain walls in LiNbO 3. JOURNAL OF MATERIALS CHEMISTRY. C 2024:d4tc02856b. [PMID: 39310799 PMCID: PMC11414182 DOI: 10.1039/d4tc02856b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Accepted: 09/10/2024] [Indexed: 09/25/2024]
Abstract
Conductive ferroelectric domain walls (DWs) hold great promise for neuromorphic nanoelectronics as they can contribute to realize multi-level diodes and nanoscale memristors. Point defects accumulating at DWs will change the local electrical transport properties. Hence, local, inter-switchable n- and p-type conductivity at DWs can be achieved through point defect population control. Here, we study the impact of point defects on the electronic structure at neutral domain walls in LiNbO3 by density functional theory (DFT). Segregation of Li and O vacancies was found to be energetically favourable at neutral DWs, implying that charge-compensating electrons or holes can give rise to n- or p-type conductivity. Changes in the electronic band gap and defect transition levels are discussed with respect to local property engineering, opening the pathway for reversible tuning between n- and p-type conduction at neutral ferroelectric DWs. Specifically, the high Curie temperature of LiNbO3 and the significant calculated mobility of O and Li vacancies suggest that thermal annealing and applied electric fields can be used experimentally to control point defect populations, and thus enable rewritable pn-junctions.
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Affiliation(s)
- Kristoffer Eggestad
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology Trondheim Norway
| | - Benjamin A D Williamson
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology Trondheim Norway
| | - Dennis Meier
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology Trondheim Norway
| | - Sverre M Selbach
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology Trondheim Norway
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2
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Conroy M, Småbråten DR, Ophus C, Shapovalov K, Ramasse QM, Hunnestad KA, Selbach SM, Aschauer U, Moore K, Gregg JM, Bangert U, Stengel M, Gruverman A, Meier D. Observation of Antiferroelectric Domain Walls in a Uniaxial Hyperferroelectric. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2405150. [PMID: 39118561 DOI: 10.1002/adma.202405150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 07/06/2024] [Indexed: 08/10/2024]
Abstract
Ferroelectric domain walls are a rich source of emergent electronic properties and unusual polar order. Recent studies show that the configuration of ferroelectric walls can go well beyond the conventional Ising-type structure. Néel-, Bloch-, and vortex-like polar patterns have been observed, displaying strong similarities with the spin textures at magnetic domain walls. Here, the discovery of antiferroelectric domain walls in the uniaxial ferroelectric Pb5Ge3O11 is reported. Highly mobile domain walls with an alternating displacement of Pb atoms are resolved, resulting in a cyclic 180° flip of dipole direction within the wall. Density functional theory calculations show that Pb5Ge3O11 is hyperferroelectric, allowing the system to overcome the depolarization fields that usually suppress the antiparallel ordering of dipoles along the longitudinal direction. Interestingly, the antiferroelectric walls observed under the electron beam are energetically more costly than basic head-to-head or tail-to-tail walls. The results suggest a new type of excited domain-wall state, expanding previous studies on ferroelectric domain walls into the realm of antiferroic phenomena.
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Affiliation(s)
- Michele Conroy
- Department of Materials, London Centre of Nanotechnology, Imperial Henry Royce Institute, Imperial College London, London, SW7 2AZ, UK
| | - Didrik René Småbråten
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Trondheim, 7491, Norway
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, CH-3012 Bern, Switzerland
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Konstantin Shapovalov
- Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, 08193, Spain
- Theoretical Materials Physics, Q-MAT, University of Liège, B-4000 Sart-Tilman, Liège, Belgium
| | - Quentin M Ramasse
- School of Physics and Astronomy, School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
- SuperSTEM, SciTech Daresbury Science and Innovation Campus, Daresbury, WA4 4AD, UK
| | - Kasper Aas Hunnestad
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Trondheim, 7491, Norway
| | - Sverre M Selbach
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Trondheim, 7491, Norway
| | - Ulrich Aschauer
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, CH-3012 Bern, Switzerland
- Department of Chemistry and Physics of Materials, University of Salzburg, Salzburg, 5020, Austria
| | | | - J Marty Gregg
- Centre for Quantum Materials and Technologies, School of Mathematics and Physics, Queen's University Belfast, Belfast, BT7 1NN, UK
| | - Ursel Bangert
- Department of Physics, Bernal Institute, University of Limerick, Limerick, V94 T9PX, Ireland
| | - Massimiliano Stengel
- Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, 08193, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys, Barcelona, 08010, Spain
| | - Alexei Gruverman
- Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, NE 68588, USA
| | - Dennis Meier
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Trondheim, 7491, Norway
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3
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Stengel M. Macroscopic Polarization from Nonlinear Gradient Couplings. PHYSICAL REVIEW LETTERS 2024; 132:146801. [PMID: 38640360 DOI: 10.1103/physrevlett.132.146801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 02/14/2024] [Indexed: 04/21/2024]
Abstract
We show that a lattice mode of arbitrary symmetry induces a well-defined macroscopic polarization at first order in the momentum and second order in the amplitude. We identify a symmetric flexoelectric-like contribution, which is sensitive to both the electrical and mechanical boundary conditions, and an antisymmetric Dzialoshinskii-Moriya-like term, which is unaffected by either. We develop the first-principles methodology to compute the relevant coupling tensors in an arbitrary crystal, which we illustrate with the example of the antiferrodistortive order parameter in SrTiO_{3}.
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Affiliation(s)
- Massimiliano Stengel
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain and ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
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4
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Li J, Su J, Zhang Q, Fang C, Liu X. Comparison of carrier doping in ZnSnO 3 and ZnTiO 3 from first principles. Phys Chem Chem Phys 2024; 26:2242-2248. [PMID: 38165283 DOI: 10.1039/d3cp04075e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Ferroelectric materials have attracted increasing attention due to their rich properties. Unlike perovskite ferroelectric oxides, in the LiNbO3-type ferroelectric oxides of ABO3, ferroelectrically active cations are not necessary. While the effects of carrier doping on perovskite ferroelectric oxides have been extensively studied, the studies on LiNbO3-type ferroelectric oxides are rare. We consider two LiNbO3-type ferroelectric oxides ZnSnO3 and ZnTiO3, where the former has no ferroelectrically active cation and the latter has ferroelectrically active cation Ti4+, and study the effect of carrier doping by performing first-principles calculations. Comparison results indicate that the B-site cation has significant effects on the polar distortion in LN-type ferroelectrics. Our studies show that LN-type materials can maintain the coexistence of ferroelectricity and conductance over a very wide range of concentrations. The polar displacement is even enhanced under hole doping. More importantly, ZnSnO3 can be doped by electrons up to a high level to realize the conducting ferroelectrics of high mobility due to its isolated s conduction band.
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Affiliation(s)
- Jing Li
- School of Physics, Shandong University, Ji'nan 250100, China.
| | - Jing Su
- School of Physics, Shandong University, Ji'nan 250100, China.
| | - Qing Zhang
- School of Physics, Shandong University, Ji'nan 250100, China.
| | - Changfeng Fang
- Center for Optics Research and Engineering (CORE) and MOE Key Laboratory of Laser & Infrared Systems, Shandong University, Qingdao 266237, China.
| | - Xiaohui Liu
- School of Physics, Shandong University, Ji'nan 250100, China.
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5
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Lu XZ, Zhang HM, Zhou Y, Zhu T, Xiang H, Dong S, Kageyama H, Rondinelli JM. Out-of-plane ferroelectricity and robust magnetoelectricity in quasi-two-dimensional materials. SCIENCE ADVANCES 2023; 9:eadi0138. [PMID: 37992171 PMCID: PMC10665001 DOI: 10.1126/sciadv.adi0138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 10/23/2023] [Indexed: 11/24/2023]
Abstract
Thin-film ferroelectrics have been pursued for capacitive and nonvolatile memory devices. They rely on polarizations that are oriented in an out-of-plane direction to facilitate integration and addressability with complementary metal-oxide semiconductor architectures. The internal depolarization field, however, formed by surface charges can suppress the out-of-plane polarization in ultrathin ferroelectric films that could otherwise exhibit lower coercive fields and operate with lower power. Here, we unveil stabilization of a polar longitudinal optical (LO) mode in the n = 2 Ruddlesden-Popper family that produces out-of-plane ferroelectricity, persists under open-circuit boundary conditions, and is distinct from hyperferroelectricity. Our first-principles calculations show the stabilization of the LO mode is ubiquitous in chalcogenides and halides and relies on anharmonic trilinear mode coupling. We further show that the out-of-plane ferroelectricity can be predicted with a crystallographic tolerance factor, and we use these insights to design a room-temperature multiferroic with strong magnetoelectric coupling suitable for magneto-electric spin-orbit transistors.
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Affiliation(s)
- Xue-Zeng Lu
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Hui-Min Zhang
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Ying Zhou
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Tong Zhu
- Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Hongjun Xiang
- Key Laboratory of Computational Physical Sciences (Ministry of Education), Institute of Computational Physical Sciences, and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
- Shanghai Qi Zhi Institute, Shanghai 200030, People's Republic of China
| | - Shuai Dong
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Hiroshi Kageyama
- Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
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6
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Zhao LX, Liu J. Origin of the negative longitudinal piezoelectric effect and electric auxetic effect in hexagonal A IB IVC V semiconductors. Phys Chem Chem Phys 2023. [PMID: 37424372 DOI: 10.1039/d3cp01717f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Hexagonal ABC semiconductors with a polar structure are potential candidates for piezoelectric applications. The intriguing negative longitudinal piezoelectric effect (NLPE) and electric auxetic effect (EAE) may exist in these materials, and establishing the structure-property relation provides physical insights into the underlying mechanisms responsible for these phenomena. In this work, using first-principles calculations, we investigate the piezoelectric response in a class of hexagonal AIBIVCV (A = Li, Na, and K; B = Ge and Sn; C = N, P, As, and Sb) semiconductors. We demonstrate that the quasi-layered structure with contrasting interlayer and intralayer bonding strengths plays a crucial role in the longitudinal piezoelectric response. In this class of materials, we identify 11 compounds out of the 24 candidates possessing the NLPE. We find that the NLPE tends to occur when the quasi-layered structure is pronounced. Moreover, we identify an unusual coexistence of negative longitudinal and transverse piezoelectric responses, and hence the compounds possessing the NLPE are electric auxetic materials as well. This work provides a simple guide for the search of piezoelectrics with desired responses.
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Affiliation(s)
- Ling-Xu Zhao
- School of Energy and Power Engineering, Shandong University, Jinan, Shandong, 250061, China.
| | - Jian Liu
- School of Energy and Power Engineering, Shandong University, Jinan, Shandong, 250061, China.
- Institute of Frontier and Interdisciplinary Science, Shandong University, Qingdao, Shandong, 266237, China
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7
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Ke C, Hu Y, Liu S. Depolarization induced III-V triatomic layers with tristable polarization states. NANOSCALE HORIZONS 2023; 8:616-623. [PMID: 36945876 DOI: 10.1039/d3nh00026e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The integration of ferroelectrics that exhibit high dielectric, piezoelectric, and thermal compatibility with the mainstream semiconductor industry will enable novel device types for widespread applications, and yet there are few silicon-compatible ferroelectrics suitable for device downscaling. We demonstrate with first-principles calculations that the enhanced depolarization field at the nanoscale can be utilized to soften unswitchable wurtzite III-V semiconductors, resulting in ultrathin two-dimensional (2D) sheets possessing reversible polarization states. A 2D sheet of AlSb consisting of three atomic planes is identified to host both ferroelectricity and antiferroelectricity, and the tristate switching is accompanied by a metal-semiconductor transition. The thermodynamic stability and potential synthesizability of the triatomic layer are corroborated with phonon spectrum calculations, ab initio molecular dynamics simulations, and variable-composition evolutionary structure search. We propose a 2D AlSb-based homojunction field effect transistor that supports three distinct and nonvolatile resistance states. This new class of III-V semiconductor-derived 2D materials with dual ferroelectricity and antiferroelectricity opens up the opportunity for nonvolatile multibit-based integrated nanoelectronics.
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Affiliation(s)
- Changming Ke
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Yihao Hu
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Shi Liu
- Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, Zhejiang 310030, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
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8
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Zhang JJ, Altalhi T, Yakobson BI. Flexo-Ferroelectricity and a Work Cycle of a Two-Dimensional-Monolayer Actuator. ACS NANO 2023; 17:5121-5128. [PMID: 36853621 DOI: 10.1021/acsnano.3c00492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Well recognized mechanical flexibility of two-dimensional (2D) materials is shown to bring about unexpected behaviors to the recently discovered monolayer ferroelectrics, especially those displaying normal, off-plane polarization. A "ferro-flexo" coupling term is introduced into the energy expression, to account for the connection of ferroelectricity and bending (strain gradient) of the layer, to predict and quantify its spontaneous curvature and how it affects the phase transitions. With InP as a chemically specific representative example, the first-principles calculations indeed reveal strong coupling ∼P·ϰ between the ferroelectric polarization (P) and the curvature of the layer (ϰ ≡ 1/r), having profound consequences for both mechanics and ferroelectricity of the material. Due to flexural relaxation, the spontaneous polarization and the transition barrier rise significantly, leading to large changes in the Curie temperature, coercive field, and domain wall width and energy, based on Monte Carlo simulations. On the other hand, the polarization switching, characteristic to ferroelectrics, does induce an overall layer bending, enabling a conversion of electrical signal to movement as an actuator; its possible work-cycles and maximum work-efficiency are briefly discussed.
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Affiliation(s)
- Jun-Jie Zhang
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Tariq Altalhi
- Chemistry Department, Taif University, Taif 21974, Saudi Arabia
| | - Boris I Yakobson
- Chemistry Department, Taif University, Taif 21974, Saudi Arabia
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
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9
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Morita K, Kumagai Y, Oba F, Walsh A. Switchable Electric Dipole from Polaron Localization in Dielectric Crystals. PHYSICAL REVIEW LETTERS 2022; 129:017601. [PMID: 35841557 DOI: 10.1103/physrevlett.129.017601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 06/05/2022] [Indexed: 06/15/2023]
Abstract
Ferroelectricity in crystals is associated with the displacement of ions or rotations of polar units. Here we consider the dipole created by donor doping (D^{+}) and the corresponding bound polaron (e^{-}). A dipole of 6.15 Debye is predicted, from Berry phase analysis, in the Ruddlesden-Popper phase of Sr_{3}Ti_{2}O_{7}. A characteristic double-well potential is formed, which persists for high doping densities. The effective Hubbard U interaction can vary the defect state from metallic, a two-dimensional polaron, through to a zero-dimensional polaron. The ferroelectriclike behavior reported here is localized and distinct from conventional spontaneous lattice polarization.
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Affiliation(s)
- Kazuki Morita
- Department of Materials, Imperial College London, London SW7 2AZ, United Kingdom
| | - Yu Kumagai
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Fumiyasu Oba
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Aron Walsh
- Department of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea
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10
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Li M, Omisakin O, Young J. Effect of chemical substitution and external strain on phase stability and ferroelectricity in two dimensional M 2CT 2 MXenes. NANOSCALE 2022; 14:6970-6980. [PMID: 35468178 DOI: 10.1039/d2nr00514j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Two dimensional ferroelectric materials are gaining increasing attention for use in ultrathin electronic devices owing to the presence of a spontaneous polarization down to one or two monolayers. However, such materials are difficult to identify, especially those with out-of-plane electric polarizations. Previous work predicted that a metastable ferroelectric phase exists in the 2D MXene Sc2CO2, while further studies have predicted that this phase exists in other MXene chemistries. However, questions remain about the origin of ferroelectricity, the stability of this phase relative to other competing phases, and the effect of external stimuli in these materials. In this work, we use density functional theory calculations to investigate 12 M2CT2 MXenes (M = transition metal, T = surface terminating group) and determine which have the ferroelectric phase as their ground state. We compute these materials' polarizations, densities of states, phonon band structures, Bader charges, and Born effective charges in the ferroelectric phase to elucidate the reasons for its stabilization. We demonstrate that this ferroelectric phase can be preferentially stabilized in non-ferroelectric MXenes through full chemical substitution of Sc or O, alloying of the Sc sites, or application of epitaxial strain. Finally, we show that these materials have excellent piezoelectric properties as well. This work provides a detailed understanding of ferroelectric MXenes and show how the number of 2D ferroelectric materials can be increased through chemical substitution or application of external stimuli.
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Affiliation(s)
- Mo Li
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, USA.
| | - Olamide Omisakin
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, USA.
| | - Joshua Young
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, USA.
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11
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Shi Q, Parsonnet E, Cheng X, Fedorova N, Peng RC, Fernandez A, Qualls A, Huang X, Chang X, Zhang H, Pesquera D, Das S, Nikonov D, Young I, Chen LQ, Martin LW, Huang YL, Íñiguez J, Ramesh R. The role of lattice dynamics in ferroelectric switching. Nat Commun 2022; 13:1110. [PMID: 35236832 PMCID: PMC8891289 DOI: 10.1038/s41467-022-28622-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 02/03/2022] [Indexed: 11/10/2022] Open
Abstract
Reducing the switching energy of ferroelectric thin films remains an important goal in the pursuit of ultralow-power ferroelectric memory and logic devices. Here, we elucidate the fundamental role of lattice dynamics in ferroelectric switching by studying both freestanding bismuth ferrite (BiFeO3) membranes and films clamped to a substrate. We observe a distinct evolution of the ferroelectric domain pattern, from striped, 71° ferroelastic domains (spacing of ~100 nm) in clamped BiFeO3 films, to large (10's of micrometers) 180° domains in freestanding films. By removing the constraints imposed by mechanical clamping from the substrate, we can realize a ~40% reduction of the switching voltage and a consequent ~60% improvement in the switching speed. Our findings highlight the importance of a dynamic clamping process occurring during switching, which impacts strain, ferroelectric, and ferrodistortive order parameters and plays a critical role in setting the energetics and dynamics of ferroelectric switching.
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Affiliation(s)
- Qiwu Shi
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
- College of Materials Science and Engineering, Sichuan University, Chengdu, 610065, China.
| | - Eric Parsonnet
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Xiaoxing Cheng
- Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania, 16802, PA, USA
| | - Natalya Fedorova
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, L-4362, Esch/Alzette, Luxembourg
| | - Ren-Ci Peng
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Information and Engineering, Xi'an Jiaotong University, 710049, Xi'an, China
- School of Advanced Materials and Nanotechnology, Xidian University, Xi'an, 710126, China
| | - Abel Fernandez
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Alexander Qualls
- Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Xiaoxi Huang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Xue Chang
- College of Materials Science and Engineering, Sichuan University, Chengdu, 610065, China
| | - Hongrui Zhang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - David Pesquera
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Sujit Das
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Material Research Centre, Indian Institute of Science, Bangalore, 560012, India
| | - Dmitri Nikonov
- Components Research, Intel Corporation, Hillsboro, OR, 97142, USA
| | - Ian Young
- Components Research, Intel Corporation, Hillsboro, OR, 97142, USA
| | - Long-Qing Chen
- Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania, 16802, PA, USA
| | - Lane W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yen-Lin Huang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan.
| | - Jorge Íñiguez
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, L-4362, Esch/Alzette, Luxembourg
- Department of Physics and Materials Science, University of Luxembourg, L-4422, Belvaux, Luxembourg
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
- Department of Physics, University of California, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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12
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Ke C, Huang J, Liu S. Two-dimensional ferroelectric metal for electrocatalysis. MATERIALS HORIZONS 2021; 8:3387-3393. [PMID: 34672306 DOI: 10.1039/d1mh01556g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The coexistence of metallicity and ferroelectricity has been an intriguing and controversial phenomenon as these two material properties are considered incompatible in bulk. We clarify the concept of the ferroelectric metal by revisiting the original definitions for ferroelectric and metal. Two-dimensional (2D) ferroelectrics with out-of-plane polarization can be engineered via layer stacking to a genuine ferroelectric metal characterized by switchable polarization and non-zero density of states at the Fermi level. We demonstrate that 2D ferroelectric metals can serve as electrically-tunable, high-quality electrocatalysts.
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Affiliation(s)
- Changming Ke
- School of Science, Westlake University, Hangzhou, Zhejiang 310024, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
- Key Laboratory for Quantum Materials of Zhejiang Province, Hangzhou, Zhejiang 310024, China
| | - Jiawei Huang
- School of Science, Westlake University, Hangzhou, Zhejiang 310024, China.
- Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Shi Liu
- School of Science, Westlake University, Hangzhou, Zhejiang 310024, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
- Key Laboratory for Quantum Materials of Zhejiang Province, Hangzhou, Zhejiang 310024, China
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13
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Li Y, Fu J, Mao X, Chen C, Liu H, Gong M, Zeng H. Enhanced bulk photovoltaic effect in two-dimensional ferroelectric CuInP 2S 6. Nat Commun 2021; 12:5896. [PMID: 34625541 PMCID: PMC8501070 DOI: 10.1038/s41467-021-26200-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 09/21/2021] [Indexed: 11/30/2022] Open
Abstract
The photocurrent generation in photovoltaics relies essentially on the interface of p-n junction or Schottky barrier with the photoelectric efficiency constrained by the Shockley-Queisser limit. The recent progress has shown a promising route to surpass this limit via the bulk photovoltaic effect for crystals without inversion symmetry. Here we report the bulk photovoltaic effect in two-dimensional ferroelectric CuInP2S6 with enhanced photocurrent density by two orders of magnitude higher than conventional bulk ferroelectric perovskite oxides. The bulk photovoltaic effect is inherently associated to the room-temperature polar ordering in two-dimensional CuInP2S6. We also demonstrate a crossover from two-dimensional to three-dimensional bulk photovoltaic effect with the observation of a dramatic decrease in photocurrent density when the thickness of the two-dimensional material exceeds the free path length at around 40 nm. This work spotlights the potential application of ultrathin two-dimensional ferroelectric materials for the third-generation photovoltaic cells.
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Affiliation(s)
- Yue Li
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Science at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
- Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, Department of Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Jun Fu
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Science at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
- Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, Department of Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Xiaoyu Mao
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Science at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
- Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, Department of Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Chen Chen
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Science at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
- Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, Department of Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Heng Liu
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Science at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
- Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, Department of Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Ming Gong
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, 230026, Hefei, People's Republic of China.
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China.
| | - Hualing Zeng
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Science at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China.
- Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, Department of Physics, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China.
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14
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Markov M, Alaerts L, Miranda HPC, Petretto G, Chen W, George J, Bousquet E, Ghosez P, Rignanese GM, Hautier G. Ferroelectricity and multiferroicity in anti-Ruddlesden-Popper structures. Proc Natl Acad Sci U S A 2021; 118:e2026020118. [PMID: 33893238 PMCID: PMC8092399 DOI: 10.1073/pnas.2026020118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Combining ferroelectricity with other properties such as visible light absorption or long-range magnetic order requires the discovery of new families of ferroelectric materials. Here, through the analysis of a high-throughput database of phonon band structures, we identify a structural family of anti-Ruddlesden-Popper phases [Formula: see text]O (A=Ca, Sr, Ba, Eu, X=Sb, P, As, Bi) showing ferroelectric and antiferroelectric behaviors. The discovered ferroelectrics belong to the new class of hyperferroelectrics that polarize even under open-circuit boundary conditions. The polar distortion involves the movement of O anions against apical A cations and is driven by geometric effects resulting from internal chemical strains. Within this structural family, we show that [Formula: see text]O combines coupled ferromagnetic and ferroelectric order at the same atomic site, a very rare occurrence in materials physics.
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Affiliation(s)
- Maxime Markov
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Louis Alaerts
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755
| | | | - Guido Petretto
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Wei Chen
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Janine George
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Eric Bousquet
- Theoretical Materials Physics, Quantum Materials Center (Q-MAT), Complex and Entangled Systems from Atoms to Materials (CESAM), Université de Liège, B-4000 Liège, Belgium
| | - Philippe Ghosez
- Theoretical Materials Physics, Quantum Materials Center (Q-MAT), Complex and Entangled Systems from Atoms to Materials (CESAM), Université de Liège, B-4000 Liège, Belgium
| | - Gian-Marco Rignanese
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Geoffroy Hautier
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium;
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755
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15
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Watanabe Y. Examination of permittivity for depolarization field of ferroelectric by ab initio calculation, suggesting hidden mechanisms. Sci Rep 2021; 11:2155. [PMID: 33495499 PMCID: PMC7835357 DOI: 10.1038/s41598-021-81237-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/01/2021] [Indexed: 11/16/2022] Open
Abstract
Electrostatics of depolarization field Ed in relation to the polarization is studied. In particular, the value of permittivity for Ed (εd) in prototypical situations of ferroelectrics, including Mehta formula, is examined by ab initio calculations. By using spontaneous polarization PS corresponding to accurate experiment ones, we show εd = 1, which suggests that the results of εd ≫ 1 indicate hidden mechanisms; εd = 1 suggests that the effect of Ed is significant to induce intriguing important phenomena overlooked by εd ≫ 1. A bridge between εd = 1 and εd ≫ 1, i.e. the consistency of εd = 1 with conventional results is presented. The exact electrostatic equality of head-to-head-tail-to-tail domains to free-standing ferroelectrics is deduced. Hence, most stoichiometric clean freestanding monodomain ferroelectrics and head-to-head-tail-to-tail domains are shown unstable regardless of size, unless partially metallic. This verifies the previous results in a transparent manner. This conclusion is shown consistent with a recent hyperferroelectric LiBeSb and "freestanding" monolayer ferroelectrics, of which origin is suggested to be adsorbates. In addition, this restriction is suggested to break in externally strained ultrathin ferroelectrics. The macroscopic formulas of Ed are found valid down to a several unit-cells, when electronic and atomic-scale surface effects are unimportant and accurate PS is used.
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16
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Urru A, Ricci F, Filippetti A, Íñiguez J, Fiorentini V. A three-order-parameter bistable magnetoelectric multiferroic metal. Nat Commun 2020; 11:4922. [PMID: 33004814 PMCID: PMC7530708 DOI: 10.1038/s41467-020-18664-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 09/04/2020] [Indexed: 11/09/2022] Open
Abstract
Using first-principles calculations we predict that the layered-perovskite metal Bi5Mn5O17 is a ferromagnet, ferroelectric, and ferrotoroid which may realize the long sought-after goal of a room-temperature ferromagnetic single-phase multiferroic with large, strongly coupled, primary-order polarization and magnetization. Bi5Mn5O17 has two nearly energy-degenerate ground states with mutually orthogonal vector order parameters (polarization, magnetization, ferrotoroidicity), which can be rotated globally by switching between ground states. Giant cross-coupling magnetoelectric and magnetotoroidic effects, as well as optical non-reciprocity, are thus expected. Importantly, Bi5Mn5O17 should be thermodynamically stable in O-rich growth conditions, and hence experimentally accessible.
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Affiliation(s)
- Andrea Urru
- Dipartimento di Fisica, Università di Cagliari, Cittadella Universitaria, Monserrato, I-09042, Cagliari, Italy
- Scuola Superiore Internazionale di Studi Avanzati, Via Bonomea 265, I-34136, Trieste, Italy
| | - Francesco Ricci
- Institute of Condensed Matter and Nanosciences (IMCN), Université Catholique de Louvain, Chemin des Étoiles 8, B-1348, Louvain-la-Neuve, Belgium
| | - Alessio Filippetti
- Dipartimento di Fisica, Università di Cagliari, Cittadella Universitaria, Monserrato, I-09042, Cagliari, Italy
- CNR-IOM, UOS Cagliari, Cittadella Universitaria, Monserrato, I-09042, Cagliari, Italy
| | - Jorge Íñiguez
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 5 avenue des Hauts-Fourneaux, L-4362, Esch/Alzette, Luxembourg
- Department of Physics and Materials Science, University of Luxembourg, 41 Rue du Brill, L-4408, Belvaux, Luxembourg
| | - Vincenzo Fiorentini
- Dipartimento di Fisica, Università di Cagliari, Cittadella Universitaria, Monserrato, I-09042, Cagliari, Italy.
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17
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Zhu L, Strobel TA, Cohen RE. Prediction of an Extended Ferroelectric Clathrate. PHYSICAL REVIEW LETTERS 2020; 125:127601. [PMID: 33016718 DOI: 10.1103/physrevlett.125.127601] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/08/2020] [Accepted: 08/14/2020] [Indexed: 06/11/2023]
Abstract
Using first-principles calculations, we predict a lightweight room-temperature ferroelectric carbon-boron framework in a host-guest clathrate structure. This ferroelectric clathrate, with composition ScB_{3}C_{3}, exhibits high polarization density and low mass density compared with widely used commercial ferroelectrics. Molecular dynamics simulations show spontaneous polarization with a moderate above-room-temperature T_{c} of ∼370 K, which implies large susceptibility and possibly large electrocaloric and piezoelectric constants at room temperature. Our findings open the possibility for a new class of ferroelectric materials with potential across a broad range of applications.
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Affiliation(s)
- Li Zhu
- Extreme Materials Initiative, Earth and Planets Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road NW, Washington, D.C. 20015, USA
| | - Timothy A Strobel
- Extreme Materials Initiative, Earth and Planets Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road NW, Washington, D.C. 20015, USA
| | - R E Cohen
- Extreme Materials Initiative, Earth and Planets Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road NW, Washington, D.C. 20015, USA
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18
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Volkov PA, Chandra P. Multiband Quantum Criticality of Polar Metals. PHYSICAL REVIEW LETTERS 2020; 124:237601. [PMID: 32603164 DOI: 10.1103/physrevlett.124.237601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 05/27/2020] [Indexed: 06/11/2023]
Abstract
Motivated by recent experimental realizations of polar metals with broken inversion symmetry, we explore the emergence of strong correlations driven by criticality when the polar transition temperature is tuned to zero. Overcoming previously discussed challenges, we demonstrate a robust mechanism for coupling between the critical mode and electrons in multiband metals. We identify and characterize several novel interacting phases, including non-Fermi liquids, when band crossings are close to the Fermi level and present their experimental signatures for three generic types of band crossings.
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Affiliation(s)
- Pavel A Volkov
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- Center for Materials Theory, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Premala Chandra
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- Center for Materials Theory, Rutgers University, Piscataway, New Jersey 08854, USA
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19
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Bennett JW. Surveying polar materials in the Inorganic Crystal Structure Database to identify emerging structure types. J SOLID STATE CHEM 2020. [DOI: 10.1016/j.jssc.2019.121045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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20
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Belviso F, Claerbout VEP, Comas-Vives A, Dalal NS, Fan FR, Filippetti A, Fiorentini V, Foppa L, Franchini C, Geisler B, Ghiringhelli LM, Groß A, Hu S, Íñiguez J, Kauwe SK, Musfeldt JL, Nicolini P, Pentcheva R, Polcar T, Ren W, Ricci F, Ricci F, Sen HS, Skelton JM, Sparks TD, Stroppa A, Urru A, Vandichel M, Vavassori P, Wu H, Yang K, Zhao HJ, Puggioni D, Cortese R, Cammarata A. Viewpoint: Atomic-Scale Design Protocols toward Energy, Electronic, Catalysis, and Sensing Applications. Inorg Chem 2019; 58:14939-14980. [DOI: 10.1021/acs.inorgchem.9b01785] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Florian Belviso
- Department of Control Engineering, Czech Technical University in Prague, Technicka 2, 16627 Prague 6, Czech Republic
| | - Victor E. P. Claerbout
- Department of Control Engineering, Czech Technical University in Prague, Technicka 2, 16627 Prague 6, Czech Republic
| | - Aleix Comas-Vives
- Department of Chemistry, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Catalonia, Spain
| | - Naresh S. Dalal
- National High Magnet Field Lab, Tallahassee, Florida 32310, United States
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Feng-Ren Fan
- Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Alessio Filippetti
- Department of Physics at University of Cagliari, and CNR-IOM, UOS Cagliari, Cittadella Universitaria, I-09042 Monserrato (CA), Italy
| | - Vincenzo Fiorentini
- Department of Physics at University of Cagliari, and CNR-IOM, UOS Cagliari, Cittadella Universitaria, I-09042 Monserrato (CA), Italy
| | - Lucas Foppa
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, CH-8093 Zürich, Switzerland
| | - Cesare Franchini
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, Sensengasse 8, A-1090 Vienna, Austria
- Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna 40127, Italy
| | - Benjamin Geisler
- Department of Physics and Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, Duisburg 47057, Germany
| | | | - Axel Groß
- Electrochemical Energy Storage, Helmholtz Institut Ulm, Ulm 89069, Germany
- Institute of Theoretical Chemistry, Ulm University, Ulm 89069, Germany
| | - Shunbo Hu
- Department of Physics, Materials Genome Institute, and International Center of Quantum and Molecular Structures, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Jorge Íñiguez
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, Avenue des Hauts-Fourneaux 5, L-4362 Esch/Alzette, Luxembourg
- Physics and Materials Research Unit, University of Luxembourg, Rue du Brill 41, Belvaux L-4422, Luxembourg
| | - Steven Kaai Kauwe
- Materials Science & Engineering Department, University of Utah, 122 Central Campus Drive, Salt Lake City, Utah 84112, United States
| | - Janice L. Musfeldt
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Paolo Nicolini
- Department of Control Engineering, Czech Technical University in Prague, Technicka 2, 16627 Prague 6, Czech Republic
| | - Rossitza Pentcheva
- Department of Physics and Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, Duisburg 47057, Germany
| | - Tomas Polcar
- Department of Control Engineering, Czech Technical University in Prague, Technicka 2, 16627 Prague 6, Czech Republic
| | - Wei Ren
- Department of Physics, Materials Genome Institute, and International Center of Quantum and Molecular Structures, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Fabio Ricci
- Physique Theorique des Materiaux, Universite de Liege, Sart-Tilman B-4000, Belgium
| | - Francesco Ricci
- Institute of Condensed Matter and Nanosciences, Universite Catholique de Louvain, Chemin des Etoiles 8, Louvain-la-Neuve B-1348, Belgium
| | - Huseyin Sener Sen
- Department of Control Engineering, Czech Technical University in Prague, Technicka 2, 16627 Prague 6, Czech Republic
| | - Jonathan Michael Skelton
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Taylor D. Sparks
- Materials Science & Engineering Department, University of Utah, 122 Central Campus Drive, Salt Lake City, Utah 84112, United States
| | - Alessandro Stroppa
- CNR-SPIN, Department of Physical Sciences and Chemistry, Universita degli Studi dell’Aquila, Via Vetoio, Coppito (AQ) 67010, Italy
| | - Andrea Urru
- Department of Physics at University of Cagliari, and CNR-IOM, UOS Cagliari, Cittadella Universitaria, I-09042 Monserrato (CA), Italy
| | - Matthias Vandichel
- Department of Chemical Sciences and Bernal Institute, Limerick University, Limerick, Ireland
- Department of Chemistry and Material Science and Department of Applied Physics, Aalto University, Espoo 02150, Finland
| | - Paolo Vavassori
- CIC nanoGUNE, San Sebastian E-20018, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao 48013, Spain
| | - Hua Wu
- Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Ke Yang
- Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Hong Jian Zhao
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, Avenue des Hauts-Fourneaux 5, L-4362 Esch/Alzette, Luxembourg
- Physics Department and Institute for Engineering, University of Arkansas, Fayetteville, Arkansas 72701,United States
| | - Danilo Puggioni
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States
| | - Remedios Cortese
- Department of Physics and Chemistry, Università degli Studi di Palermo, Viale delle Scienze ed. 17, Palermo 90128, Italy
| | - Antonio Cammarata
- Department of Control Engineering, Czech Technical University in Prague, Technicka 2, 16627 Prague 6, Czech Republic
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21
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Lindgren G, Ievlev A, Jesse S, Ovchinnikova OS, Kalinin SV, Vasudevan RK, Canalias C. Elasticity Modulation Due to Polarization Reversal and Ionic Motion in the Ferroelectric Superionic Conductor KTiOPO 4. ACS APPLIED MATERIALS & INTERFACES 2018; 10:32298-32303. [PMID: 30152677 DOI: 10.1021/acsami.8b07537] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The coupling between ionic degrees of freedom and ferroelectricity has received renewed attention in recent years, given that surface electrochemical processes have been shown to be intrinsically linked to ferroelectric phase stability in ultrathin ferroelectric films. However, the coupling between bulk ionic transport and local polarization switching has received less attention, as typically the bulk ionic mobilities are low for common ferroelectrics at room temperature. Here, we use the coupled band-excitation method in conjunction with site-correlated time-of-flight secondary ion mass spectrometry, to determine the coupling between ferroelectric switching and ionic motion in single crystal KTiOPO4. The local scanning probe measurements indicate a substantial softening, as determined by resonant frequency changes, during reversal of polarization along one direction. These changes are correlated with the mass spectrometry measurements, showing a polarization-dependent accumulation of K ions at the polar surfaces, thus corroborating their role in the screening process. These studies shed light on the interplay between ionic dynamics and bulk ferroelectric switching and have implications for studies on domain wall conductivity, chemical switching, and bulk and surface-screening phenomena.
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Affiliation(s)
- Gustav Lindgren
- Department of Applied Physics , Royal Institute of Technology , Roslagstullsbacken 21 , 10691 Stockholm , Sweden
| | | | | | | | | | | | - Carlota Canalias
- Department of Applied Physics , Royal Institute of Technology , Roslagstullsbacken 21 , 10691 Stockholm , Sweden
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22
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23
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Garrity KF. High-throughput first principles search for new ferroelectrics. PHYSICAL REVIEW. B 2018; 97:10.1103/PhysRevB.97.024115. [PMID: 30984897 PMCID: PMC6459619 DOI: 10.1103/physrevb.97.024115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We use a combination of symmetry analysis and high-throughput density functional theory calculations to search for new ferroelectric materials. We use two search strategies to identify candidate materials. In the first strategy, we start with non-polar materials and look for unrecognized energy-lowering polar distortions. In the second strategy, we consider polar materials and look for related higher symmetry structures. In both cases, if we find new structures with the correct symmetries that are also close in energy to experimentally known structures, then the material is likely to be switchable in an external electric field, making it a candidate ferroelectric. We find sixteen candidate materials, with variety of properties that are rare in typical ferroelectrics, including large polarization, hyperferroelectricity, antiferroelectricity, and multiferroism.
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Affiliation(s)
- Kevin F. Garrity
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg MD, 20899
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24
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Liu S, Cohen RE. Origin of Negative Longitudinal Piezoelectric Effect. PHYSICAL REVIEW LETTERS 2017; 119:207601. [PMID: 29219344 DOI: 10.1103/physrevlett.119.207601] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Indexed: 06/07/2023]
Abstract
Piezoelectrics with negative longitudinal piezoelectric coefficients will contract in the direction of an applied electric field. Such piezoelectrics are thought to be rare, but there is no fundamental physics preventing the realization of negative longitudinal piezoelectric effect in a single-phase material. Using first-principles calculations, we demonstrate that several hexagonal ABC ferroelectrics possess significant negative longitudinal piezoelectric effects. The data mining of a first-principles-based database of piezoelectrics reveals that this effect is a general phenomenon. The origin of this unusual piezoelectric response relies on the strong ionic bonds associated with small effective charges and rigid potential energy surfaces. Moreover, ferroelectrics with negative longitudinal piezoelectric coefficients show anomalous pressure-enhanced ferroelectricity. Our results offer design principles to aid the search for new piezoelectrics for novel electromechanical device applications.
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Affiliation(s)
- Shi Liu
- Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution for Science, Washington, DC 20015-1305, USA
| | - R E Cohen
- Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution for Science, Washington, DC 20015-1305, USA
- Department of Earth- and Environmental Sciences, Ludwig Maximilians Universität, Munich 80333, Germany
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25
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Monserrat B, Bennett JW, Rabe KM, Vanderbilt D. Antiferroelectric Topological Insulators in Orthorhombic AMgBi Compounds (A=Li, Na, K). PHYSICAL REVIEW LETTERS 2017; 119:036802. [PMID: 28777633 DOI: 10.1103/physrevlett.119.036802] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Indexed: 06/07/2023]
Abstract
We introduce antiferroelectric topological insulators as a new class of functional materials in which an electric field can be used to control topological order and induce topological phase transitions. Using first principles methods, we predict that several alkali-MgBi orthorhombic members of an ABC family of compounds are antiferroelectric topological insulators. We also show that epitaxial strain and hydrostatic pressure can be used to tune the topological order and the band gap of these ABC compounds. Antiferroelectric topological insulators could enable precise control of topology using electric fields, enhancing the applicability of topological materials in electronics and spintronics.
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Affiliation(s)
- Bartomeu Monserrat
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA
- TCM Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Joseph W Bennett
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA
| | - Karin M Rabe
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA
| | - David Vanderbilt
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA
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26
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Liu S, Cohen RE. Stable charged antiparallel domain walls in hyperferroelectrics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:244003. [PMID: 28443824 DOI: 10.1088/1361-648x/aa6f95] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Charge-neutral 180° domain walls that separate domains of antiparallel polarization directions are common structural topological defects in ferroelectrics. In normal ferroelectrics, charged 180° domain walls running perpendicular to the polarization directions are highly energetically unfavorable because of the depolarization field and are difficult to stabilize. We explore both neutral and charged 180° domain walls in hyperferroelectrics, a class of proper ferroelectrics with persistent polarization in the presence of a depolarization field, using density functional theory. We obtain zero temperature equilibrium structures of head-to-head and tail-to-tail walls in recently discovered ABC-type hexagonal hyperferroelectrics. Charged domain walls can also be stabilized in canonical ferroelectrics represented by LiNbO3 without any dopants, defects or mechanical clamping. First-principles electronic structure calculations show that charged domain walls can reduce and even close the band gap of host materials and support quasi-two-dimensional electron(hole) gas with enhanced electrical conductivity.
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Affiliation(s)
- S Liu
- Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution for Science, Washington, DC 20015-1305, United States of America
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Gu T, Luo W, Xiang H. Prediction of two‐dimensional materials by the global optimization approach. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2016. [DOI: 10.1002/wcms.1295] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Teng Gu
- Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of PhysicsFudan University Shanghai P. R. China
- Collaborative Innovation Center of Advanced Microstructures Nanjing P. R. China
| | - Wei Luo
- Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of PhysicsFudan University Shanghai P. R. China
- Collaborative Innovation Center of Advanced Microstructures Nanjing P. R. China
| | - Hongjun Xiang
- Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of PhysicsFudan University Shanghai P. R. China
- Collaborative Innovation Center of Advanced Microstructures Nanjing P. R. China
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28
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Davies DW, Butler KT, Jackson AJ, Morris A, Frost JM, Skelton JM, Walsh A. Computational Screening of All Stoichiometric Inorganic Materials. Chem 2016; 1:617-627. [PMID: 27790643 PMCID: PMC5074417 DOI: 10.1016/j.chempr.2016.09.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 06/28/2016] [Accepted: 09/21/2016] [Indexed: 11/01/2022]
Abstract
Forming a four-component compound from the first 103 elements of the periodic table results in more than 1012 combinations. Such a materials space is intractable to high-throughput experiment or first-principle computation. We introduce a framework to address this problem and quantify how many materials can exist. We apply principles of valency and electronegativity to filter chemically implausible compositions, which reduces the inorganic quaternary space to 1010 combinations. We demonstrate that estimates of band gaps and absolute electron energies can be made simply on the basis of the chemical composition and apply this to the search for new semiconducting materials to support the photoelectrochemical splitting of water. We show the applicability to predicting crystal structure by analogy with known compounds, including exploration of the phase space for ternary combinations that form a perovskite lattice. Computer screening reproduces known perovskite materials and predicts the feasibility of thousands more. Given the simplicity of the approach, large-scale searches can be performed on a single workstation.
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Affiliation(s)
- Daniel W Davies
- Department of Chemistry, Centre for Sustainable Chemical Technologies, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Keith T Butler
- Department of Chemistry, Centre for Sustainable Chemical Technologies, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Adam J Jackson
- Department of Chemistry, Centre for Sustainable Chemical Technologies, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Andrew Morris
- Department of Chemistry, Centre for Sustainable Chemical Technologies, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Jarvist M Frost
- Department of Chemistry, Centre for Sustainable Chemical Technologies, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Jonathan M Skelton
- Department of Chemistry, Centre for Sustainable Chemical Technologies, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Aron Walsh
- Department of Chemistry, Centre for Sustainable Chemical Technologies, University of Bath, Claverton Down, Bath BA2 7AY, UK; Department of Materials Science and Engineering, Global E Institute, Yonsei University, Seoul 120-749, Korea; Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, UK
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Li P, Ren X, Guo GC, He L. The origin of hyperferroelectricity in LiBO 3 (B = V, Nb, Ta, Os). Sci Rep 2016; 6:34085. [PMID: 27694996 PMCID: PMC5046123 DOI: 10.1038/srep34085] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/05/2016] [Indexed: 11/30/2022] Open
Abstract
The electronic and structural properties of LiBO3 (B = V, Nb, Ta, Os) are investigated via first-principles methods. We show that LiBO3 belong to the recently proposed hyperferroelectrics (hyperFEs), i.e., they all have unstable longitudinal optic phonon modes. Especially, the ferroelectric-like instability in the metal LiOsO3, whose optical dielectric constant goes to infinity, is a limiting case of hyperFEs. Via an effective Hamiltonian, we further show that, in contrast to normal proper ferroelectricity, in which the ferroelectric instability usually comes from long-range coulomb interactions, the hyperFE instability is due to the structure instability driven by short-range interactions. This could happen in systems with large ion size mismatches, which therefore provides a useful guidance in searching for novel hyperFEs.
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Affiliation(s)
- Pengfei Li
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Xinguo Ren
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Guang-Can Guo
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Lixin He
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, China
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Fei R, Kang W, Yang L. Ferroelectricity and Phase Transitions in Monolayer Group-IV Monochalcogenides. PHYSICAL REVIEW LETTERS 2016; 117:097601. [PMID: 27610884 DOI: 10.1103/physrevlett.117.097601] [Citation(s) in RCA: 188] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Indexed: 05/25/2023]
Abstract
Ferroelectricity usually fades away as materials are thinned down below a critical value. We reveal that the unique ionic-potential anharmonicity can induce spontaneous in-plane electrical polarization and ferroelectricity in monolayer group-IV monochalcogenides MX (M=Ge, Sn; X=S, Se). An effective Hamiltonian has been successfully extracted from the parametrized energy space, making it possible to study the ferroelectric phase transitions in a single-atom layer. The ferroelectricity in these materials is found to be robust and the corresponding Curie temperatures are higher than room temperature, making them promising for realizing ultrathin ferroelectric devices of broad interest. We further provide the phase diagram and predict other potentially two-dimensional ferroelectric materials.
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Affiliation(s)
- Ruixiang Fei
- Department of Physics and Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Wei Kang
- HEDPS, Center for Applied Physics and Technology, and College of Engineering, Peking University, Beijing 100871, China
| | - Li Yang
- Department of Physics and Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
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Di Sante D, Barone P, Stroppa A, Garrity KF, Vanderbilt D, Picozzi S. Intertwined Rashba, Dirac, and Weyl Fermions in Hexagonal Hyperferroelectrics. PHYSICAL REVIEW LETTERS 2016; 117:076401. [PMID: 27563977 DOI: 10.1103/physrevlett.117.076401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Indexed: 06/06/2023]
Abstract
By means of density functional theory based calculations, we study the role of spin-orbit coupling in the new family of ABC hyperferroelectrics [Garrity, Rabe, and Vanderbilt Phys. Rev. Lett. 112, 127601 (2014)]. We unveil an extremely rich physics strongly linked to ferroelectric properties, ranging from the electric control of bulk Rashba effect to the existence of a three-dimensional topological insulator phase, with concomitant topological surface states even in the ultrathin film limit. Moreover, we predict that the topological transition, as induced by alloying, is followed by a Weyl semimetal phase of finite concentration extension, which is robust against disorder, putting forward hyperferroelectrics as promising candidates for spin-orbitronic applications.
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Affiliation(s)
- Domenico Di Sante
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland Campus Süd, Würzburg 97074, Germany
- Consiglio Nazionale delle Ricerche (CNR-SPIN), Via Vetoio, L'Aquila 67100, Italy
| | - Paolo Barone
- Consiglio Nazionale delle Ricerche (CNR-SPIN), Via Vetoio, L'Aquila 67100, Italy
- Graphene Labs, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy
| | - Alessandro Stroppa
- Consiglio Nazionale delle Ricerche (CNR-SPIN), Via Vetoio, L'Aquila 67100, Italy
| | - Kevin F Garrity
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg Maryland, 20899, USA
| | - David Vanderbilt
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Silvia Picozzi
- Consiglio Nazionale delle Ricerche (CNR-SPIN), Via Vetoio, L'Aquila 67100, Italy
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Luo W, Xiang H. Two-Dimensional Phosphorus Oxides as Energy and Information Materials. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201602295] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Wei Luo
- Key Laboratory of Computational Physical Sciences (Ministry of Education); State Key Laboratory of Surface Physics and Department of Physics; Fudan University; Shanghai 200433 China
- Collaborative Innovation Center of Advanced Microstructures; Nanjing 210093 China
| | - 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 China
- Collaborative Innovation Center of Advanced Microstructures; Nanjing 210093 China
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Luo W, Xiang H. Two-Dimensional Phosphorus Oxides as Energy and Information Materials. Angew Chem Int Ed Engl 2016; 55:8575-80. [DOI: 10.1002/anie.201602295] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 04/15/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Wei Luo
- Key Laboratory of Computational Physical Sciences (Ministry of Education); State Key Laboratory of Surface Physics and Department of Physics; Fudan University; Shanghai 200433 China
- Collaborative Innovation Center of Advanced Microstructures; Nanjing 210093 China
| | - 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 China
- Collaborative Innovation Center of Advanced Microstructures; Nanjing 210093 China
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Abstract
Over 50 years ago, Anderson and Blount discussed symmetry-allowed polar distortions in metals, spawning the idea that a material might be simultaneously metallic and ferroelectric. While many studies have ever since considered such or similar situations, actual ferroelectricity—that is, the existence of a switchable intrinsic electric polarization—has not yet been attained in a metal, and is in fact generally deemed incompatible with the screening by mobile conduction charges. Here we refute this common wisdom and show, by means of first-principles simulations, that native metallicity and ferroelectricity coexist in the layered perovskite Bi5Ti5O17. We show that, despite being a metal, Bi5Ti5O17 can sustain a sizable potential drop along the polar direction, as needed to reverse its polarization by an external bias. We also reveal striking behaviours, as the self-screening mechanism at work in thin Bi5Ti5O17 layers, emerging from the interplay between polar distortions and carriers in this compound. Ferroelectricity, spontaneous switchable polarization, is usually deemed incompatible with the electronic screening of a metal. Here, the authors use ab initio theory to predict that metallicity natively coexists with ferroelectric polarization and finite depolarizing fields in the perovskite Bi5Ti5O17.
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