1
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Martis J, Susarla S, Rayabharam A, Su C, Paule T, Pelz P, Huff C, Xu X, Li HK, Jaikissoon M, Chen V, Pop E, Saraswat K, Zettl A, Aluru NR, Ramesh R, Ercius P, Majumdar A. Imaging the electron charge density in monolayer MoS 2 at the Ångstrom scale. Nat Commun 2023; 14:4363. [PMID: 37474521 PMCID: PMC10359339 DOI: 10.1038/s41467-023-39304-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 06/06/2023] [Indexed: 07/22/2023] Open
Abstract
Four-dimensional scanning transmission electron microscopy (4D-STEM) has recently gained widespread attention for its ability to image atomic electric fields with sub-Ångstrom spatial resolution. These electric field maps represent the integrated effect of the nucleus, core electrons and valence electrons, and separating their contributions is non-trivial. In this paper, we utilized simultaneously acquired 4D-STEM center of mass (CoM) images and annular dark field (ADF) images to determine the projected electron charge density in monolayer MoS2. We evaluate the contributions of both the core electrons and the valence electrons to the derived electron charge density; however, due to blurring by the probe shape, the valence electron contribution forms a nearly featureless background while most of the spatial modulation comes from the core electrons. Our findings highlight the importance of probe shape in interpreting charge densities derived from 4D-STEM and the need for smaller electron probes.
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Affiliation(s)
- Joel Martis
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Sandhya Susarla
- The National Center for Electron Microscopy (NCEM), The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Archith Rayabharam
- Department of Mechanical Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Cong Su
- Department of Physics, University of California Berkeley, Berkeley, CA, USA
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, USA
- Kavli Energy NanoScience Institute, University of California Berkeley, Berkeley, CA, USA
| | - Timothy Paule
- Department of Physics, University of California Berkeley, Berkeley, CA, USA
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, USA
- Kavli Energy NanoScience Institute, University of California Berkeley, Berkeley, CA, USA
| | - Philipp Pelz
- The National Center for Electron Microscopy (NCEM), The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Institute of Micro- and Nanostructure Research & Center for Nanoanalysis and Electron Microscopy (CENEM), Department of Materials Science, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Cassandra Huff
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Xintong Xu
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Hao-Kun Li
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Marc Jaikissoon
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Victoria Chen
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Eric Pop
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Krishna Saraswat
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Alex Zettl
- Department of Physics, University of California Berkeley, Berkeley, CA, USA
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, USA
- Kavli Energy NanoScience Institute, University of California Berkeley, Berkeley, CA, USA
| | - Narayana R Aluru
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Ramamoorthy Ramesh
- Department of Physics, University of California Berkeley, Berkeley, CA, USA
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, USA
| | - Peter Ercius
- The National Center for Electron Microscopy (NCEM), The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Arun Majumdar
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
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2
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Kim D, Kim Y, Sohn B, Kim M, Kim B, Noh TW, Kim C. Electric Control of 2D Van Hove Singularity in Oxide Ultra-Thin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2207188. [PMID: 36764325 DOI: 10.1002/adma.202207188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 01/02/2023] [Indexed: 05/17/2023]
Abstract
Divergent density of states (DOS) can induce extraordinary phenomena such as significant enhancement of superconductivity and unexpected phase transitions. Moreover, van Hove singularities (VHSs) lead to divergent DOS in 2D systems. Despite recent interest in VHSs, only a few controllable cases have been reported to date. In this work, by utilizing an atomically ultra-thin SrRuO3 film, the electronic structure of a 2D VHS is investigated with angle-resolved photoemission spectroscopy and transport properties are controlled. By applying electric fields with alkali metal deposition and ionic-liquid gating methods, the 2D VHS and the sign of the charge carrier are precisely controlled. Use of a tunable 2D VHS in an atomically flat oxide film could serve as a new strategy to realize infinite DOS near the Fermi level, thereby allowing efficient tuning of electric properties.
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Affiliation(s)
- Donghan Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Younsik Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Byungmin Sohn
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Minsoo Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Bongju Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
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3
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Das S, Laguta V, Inzani K, Huang W, Liu J, Chatterjee R, McCarter MR, Susarla S, Ardavan A, Junquera J, Griffin SM, Ramesh R. Inherent Spin-Polarization Coupling in a Magnetoelectric Vortex. NANO LETTERS 2022; 22:3976-3982. [PMID: 35561341 DOI: 10.1021/acs.nanolett.2c00496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Solid-state materials are currently being explored as a platform for the manipulation of spins for spintronics and quantum information science. More broadly, a wide spectrum of ferroelectric materials, spanning from inorganic oxides to polymeric systems such as PVDF, present a different approach to explore quantum phenomena in which the spins are set and manipulated with electric fields. Using dilute Fe3+-doped ferroelectric PbTiO3-SrTiO3 superlattices as a model system, we demonstrate intrinsic spin-polarization control of spin directionality in complex ferroelectric vortices and skyrmions. Electron paramagnetic resonance (EPR) spectra show that the spins in the Fe3+ ion are strongly coupled to the local polarization and preferentially aligned perpendicular to the ferroelectric polar c axis in this complex vortex structure. The effect of polarization-spin directionality is corroborated by first-principles calculations, demonstrating the variation of the spin directionality with the polar texture and offering the potential for future quantum analogues of macroscopic magnetoelectric devices.
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Affiliation(s)
- Sujit Das
- Material Research Centre, Indian Institute of Science, Bangalore 560012, India
| | - Valentyn Laguta
- Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic
| | - Katherine Inzani
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Weichuan Huang
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
| | - Junjie Liu
- CAESR, Department of Physics, University of Oxford, The Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Ruchira Chatterjee
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Margaret R McCarter
- Department of Physics, University of California, Berkeley, California 94720, United States
| | - Sandhya Susarla
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Arzhang Ardavan
- CAESR, Department of Physics, University of Oxford, The Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Javier Junquera
- Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Cantabria Campus Internacional, Avenida de los Castros s/n, E-39005 Santander, Spain
| | - 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
| | - Ramamoorthy Ramesh
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
- Department of Physics, University of California, Berkeley, California 94720, United States
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4
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Comparing Thickness and Doping-Induced Effects on the Normal States of Infinite-Layer Electron-Doped Cuprates: Is There Anything to Learn? NANOMATERIALS 2022; 12:nano12071092. [PMID: 35407212 PMCID: PMC9044742 DOI: 10.3390/nano12071092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 11/25/2022]
Abstract
We grew Sr1-xLaxCuO2 thin films and SrCuO2/Sr0.9La0.1CuO2/SrCuO2 trilayers by reflection high-energy diffraction-calibrated layer-by-layer molecular beam epitaxy, to study their electrical transport properties as a function of the doping and thickness of the central Sr0.9La0.1CuO2 layer. For the trilayer samples, as already observed in underdoped SLCO films, the electrical resistivity versus temperature curves as a function of the central layer thickness show, for thicknesses thinner than 20 unit cells, sudden upturns in the low temperature range with the possibility for identifying, in the normal state, the T* and a T** temperatures, respectively, separating high-temperature linear behavior and low-temperature quadratic dependence. By plotting the T* and T** values as a function of TConset for both the thin films and the trilayers, the data fall on the same curves. This result suggests that, for the investigated trilayers, the superconducting critical temperature is the important parameter able to describe the normal state properties and that, in the limit of very thin central layers, such properties are mainly influenced by the modification of the energy band structure and not by interface-related disorder.
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5
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Yang Y, Peltier CR, Zeng R, Schimmenti R, Li Q, Huang X, Yan Z, Potsi G, Selhorst R, Lu X, Xu W, Tader M, Soudackov AV, Zhang H, Krumov M, Murray E, Xu P, Hitt J, Xu L, Ko HY, Ernst BG, Bundschu C, Luo A, Markovich D, Hu M, He C, Wang H, Fang J, DiStasio RA, Kourkoutis LF, Singer A, Noonan KJT, Xiao L, Zhuang L, Pivovar BS, Zelenay P, Herrero E, Feliu JM, Suntivich J, Giannelis EP, Hammes-Schiffer S, Arias T, Mavrikakis M, Mallouk TE, Brock JD, Muller DA, DiSalvo FJ, Coates GW, Abruña HD. Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies. Chem Rev 2022; 122:6117-6321. [PMID: 35133808 DOI: 10.1021/acs.chemrev.1c00331] [Citation(s) in RCA: 89] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Hydrogen energy-based electrochemical energy conversion technologies offer the promise of enabling a transition of the global energy landscape from fossil fuels to renewable energy. Here, we present a comprehensive review of the fundamentals of electrocatalysis in alkaline media and applications in alkaline-based energy technologies, particularly alkaline fuel cells and water electrolyzers. Anion exchange (alkaline) membrane fuel cells (AEMFCs) enable the use of nonprecious electrocatalysts for the sluggish oxygen reduction reaction (ORR), relative to proton exchange membrane fuel cells (PEMFCs), which require Pt-based electrocatalysts. However, the hydrogen oxidation reaction (HOR) kinetics is significantly slower in alkaline media than in acidic media. Understanding these phenomena requires applying theoretical and experimental methods to unravel molecular-level thermodynamics and kinetics of hydrogen and oxygen electrocatalysis and, particularly, the proton-coupled electron transfer (PCET) process that takes place in a proton-deficient alkaline media. Extensive electrochemical and spectroscopic studies, on single-crystal Pt and metal oxides, have contributed to the development of activity descriptors, as well as the identification of the nature of active sites, and the rate-determining steps of the HOR and ORR. Among these, the structure and reactivity of interfacial water serve as key potential and pH-dependent kinetic factors that are helping elucidate the origins of the HOR and ORR activity differences in acids and bases. Additionally, deliberately modulating and controlling catalyst-support interactions have provided valuable insights for enhancing catalyst accessibility and durability during operation. The design and synthesis of highly conductive and durable alkaline membranes/ionomers have enabled AEMFCs to reach initial performance metrics equal to or higher than those of PEMFCs. We emphasize the importance of using membrane electrode assemblies (MEAs) to integrate the often separately pursued/optimized electrocatalyst/support and membranes/ionomer components. Operando/in situ methods, at multiscales, and ab initio simulations provide a mechanistic understanding of electron, ion, and mass transport at catalyst/ionomer/membrane interfaces and the necessary guidance to achieve fuel cell operation in air over thousands of hours. We hope that this Review will serve as a roadmap for advancing the scientific understanding of the fundamental factors governing electrochemical energy conversion in alkaline media with the ultimate goal of achieving ultralow Pt or precious-metal-free high-performance and durable alkaline fuel cells and related technologies.
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Affiliation(s)
- Yao Yang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Cheyenne R Peltier
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Rui Zeng
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Roberto Schimmenti
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Qihao Li
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Xin Huang
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
| | - Zhifei Yan
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Georgia Potsi
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Ryan Selhorst
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Xinyao Lu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Weixuan Xu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Mariel Tader
- Department of Physics, Cornell University, Ithaca, New York 14853, United States
| | - Alexander V Soudackov
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Hanguang Zhang
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Mihail Krumov
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Ellen Murray
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Pengtao Xu
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Jeremy Hitt
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Linxi Xu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Hsin-Yu Ko
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Brian G Ernst
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Colin Bundschu
- Department of Physics, Cornell University, Ithaca, New York 14853, United States
| | - Aileen Luo
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Danielle Markovich
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
| | - Meixue Hu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Cheng He
- Chemical and Materials Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Hongsen Wang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Jiye Fang
- Department of Chemistry, State University of New York at Binghamton, Binghamton, New York 13902, United States
| | - Robert A DiStasio
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States.,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
| | - Andrej Singer
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Kevin J T Noonan
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Li Xiao
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Lin Zhuang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Bryan S Pivovar
- Chemical and Materials Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Piotr Zelenay
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Enrique Herrero
- Instituto de Electroquímica, Universidad de Alicante, Alicante E-03080, Spain
| | - Juan M Feliu
- Instituto de Electroquímica, Universidad de Alicante, Alicante E-03080, Spain
| | - Jin Suntivich
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States.,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
| | - Emmanuel P Giannelis
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
| | | | - Tomás Arias
- Department of Physics, Cornell University, Ithaca, New York 14853, United States
| | - Manos Mavrikakis
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Thomas E Mallouk
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Joel D Brock
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States.,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
| | - Francis J DiSalvo
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Geoffrey W Coates
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Héctor D Abruña
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States.,Center for Alkaline Based Energy Solutions (CABES), Cornell University, Ithaca, New York 14853, United States
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6
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Liu JJ. Advances and Applications of Atomic-Resolution Scanning Transmission Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2021; 27:1-53. [PMID: 34414878 DOI: 10.1017/s1431927621012125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Although scanning transmission electron microscopy (STEM) images of individual heavy atoms were reported 50 years ago, the applications of atomic-resolution STEM imaging became wide spread only after the practical realization of aberration correctors on field-emission STEM/TEM instruments to form sub-Ångstrom electron probes. The innovative designs and advances of electron optical systems, the fundamental understanding of electron–specimen interaction processes, and the advances in detector technology all played a major role in achieving the goal of atomic-resolution STEM imaging of practical materials. It is clear that tremendous advances in computer technology and electronics, image acquisition and processing algorithms, image simulations, and precision machining synergistically made atomic-resolution STEM imaging routinely accessible. It is anticipated that further hardware/software development is needed to achieve three-dimensional atomic-resolution STEM imaging with single-atom chemical sensitivity, even for electron-beam-sensitive materials. Artificial intelligence, machine learning, and big-data science are expected to significantly enhance the impact of STEM and associated techniques on many research fields such as materials science and engineering, quantum and nanoscale science, physics and chemistry, and biology and medicine. This review focuses on advances of STEM imaging from the invention of the field-emission electron gun to the realization of aberration-corrected and monochromated atomic-resolution STEM and its broad applications.
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Affiliation(s)
- Jingyue Jimmy Liu
- Department of Physics, Arizona State University, Tempe, AZ85287, USA
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7
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King PDC, Picozzi S, Egdell RG, Panaccione G. Angle, Spin, and Depth Resolved Photoelectron Spectroscopy on Quantum Materials. Chem Rev 2021; 121:2816-2856. [PMID: 33346644 DOI: 10.1021/acs.chemrev.0c00616] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of X-ray based electron spectroscopies in determining chemical, electronic, and magnetic properties of solids has been well-known for several decades. A powerful approach is angle-resolved photoelectron spectroscopy, whereby the kinetic energy and angle of photoelectrons emitted from a sample surface are measured. This provides a direct measurement of the electronic band structure of crystalline solids. Moreover, it yields powerful insights into the electronic interactions at play within a material and into the control of spin, charge, and orbital degrees of freedom, central pillars of future solid state science. With strong recent focus on research of lower-dimensional materials and modified electronic behavior at surfaces and interfaces, angle-resolved photoelectron spectroscopy has become a core technique in the study of quantum materials. In this review, we provide an introduction to the technique. Through examples from several topical materials systems, including topological insulators, transition metal dichalcogenides, and transition metal oxides, we highlight the types of information which can be obtained. We show how the combination of angle, spin, time, and depth-resolved experiments are able to reveal "hidden" spectral features, connected to semiconducting, metallic and magnetic properties of solids, as well as underlining the importance of dimensional effects in quantum materials.
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Affiliation(s)
- Phil D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Silvia Picozzi
- Consiglio Nazionale delle Ricerche, CNR-SPIN, Via dei Vestini 31, Chieti 66100, Italy
| | - Russell G Egdell
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Giancarlo Panaccione
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
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8
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Mori R, Marshall PB, Ahadi K, Denlinger JD, Stemmer S, Lanzara A. Controlling a Van Hove singularity and Fermi surface topology at a complex oxide heterostructure interface. Nat Commun 2019; 10:5534. [PMID: 31797932 PMCID: PMC6892806 DOI: 10.1038/s41467-019-13046-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 10/16/2019] [Indexed: 11/10/2022] Open
Abstract
The emergence of saddle-point Van Hove singularities (VHSs) in the density of states, accompanied by a change in Fermi surface topology, Lifshitz transition, constitutes an ideal ground for the emergence of different electronic phenomena, such as superconductivity, pseudo-gap, magnetism, and density waves. However, in most materials the Fermi level, \documentclass[12pt]{minimal}
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\begin{document}$${E}_{{\rm{F}}}$$\end{document}EF, is too far from the VHS where the change of electronic topology takes place, making it difficult to reach with standard chemical doping or gating techniques. Here, we demonstrate that this scenario can be realized at the interface between a Mott insulator and a band insulator as a result of quantum confinement and correlation enhancement, and easily tuned by fine control of layer thickness and orbital occupancy. These results provide a tunable pathway for Fermi surface topology and VHS engineering of electronic phases. A singularity in a material’s density of states at the Fermi energy can drive the formation of unconventional electronic phases. Here the authors show a Van Hove singularity is tunable across the Fermi energy in an oxide heterostructure, leading to enhanced electronic correlations.
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Affiliation(s)
- Ryo Mori
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Applied Science & Technology, University of California, Berkeley, CA, 94720, USA
| | - Patrick B Marshall
- Materials Department, University of California, Santa Barbara, CA, 93106-5050, USA
| | - Kaveh Ahadi
- Materials Department, University of California, Santa Barbara, CA, 93106-5050, USA
| | - Jonathan D Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Susanne Stemmer
- Materials Department, University of California, Santa Barbara, CA, 93106-5050, USA
| | - Alessandra Lanzara
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. .,Department of Physics, University of California, Berkeley, CA, 94720, USA.
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9
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Cook S, Letchworth-Weaver K, Tung IC, Andersen TK, Hong H, Marks LD, Fong DD. How heteroepitaxy occurs on strontium titanate. SCIENCE ADVANCES 2019; 5:eaav0764. [PMID: 30993200 PMCID: PMC6461459 DOI: 10.1126/sciadv.aav0764] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 02/14/2019] [Indexed: 06/01/2023]
Abstract
In traditional models of heteroepitaxy, the substrate serves mainly as a crystalline template for the thin-film lattice, dictating the initial roughness of the film and the degree of coherent strain. Here, performing in situ surface x-ray diffraction during the heteroepitaxial growth of LaTiO3 on SrTiO3 (001), we find that a TiO2 adlayer composed of the ( 13 × 13 ) R33.7° and ( 2 × 2 ) R45.0° reconstructions is a highly active participant in the growth process, continually diffusing to the surface throughout deposition. The effects of the TiO2 adlayer on layer-by-layer growth are investigated using different deposition sequences and anomalous x-ray scattering, both of which permit detailed insight into the dynamic layer rearrangements that take place. Our work challenges commonly held assumptions regarding growth on TiO2-terminated SrTiO3 (001) and demonstrates the critical role of excess TiO2 surface stoichiometry on the initial stages of heteroepitaxial growth on this important perovskite oxide substrate material.
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Affiliation(s)
- Seyoung Cook
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60202, USA
| | | | - I-Cheng Tung
- X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Tassie K. Andersen
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60202, USA
| | - Hawoong Hong
- X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Laurence D. Marks
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60202, USA
| | - Dillon D. Fong
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
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10
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Chen A, Su Q, Han H, Enriquez E, Jia Q. Metal Oxide Nanocomposites: A Perspective from Strain, Defect, and Interface. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1803241. [PMID: 30368932 DOI: 10.1002/adma.201803241] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 08/13/2018] [Indexed: 06/08/2023]
Abstract
Vertically aligned nanocomposite thin films with ordered two phases, grown epitaxially on substrates, have attracted tremendous interest in the past decade. These unique nanostructured composite thin films with large vertical interfacial area, controllable vertical lattice strain, and defects provide an intriguing playground, allowing for the manipulation of a variety of functional properties of the materials via the interplay among strain, defect, and interface. This field has evolved from basic growth and characterization to functionality tuning as well as potential applications in energy conversion and information technology. Here, the remarkable progress achieved in vertically aligned nanocomposite thin films from a perspective of tuning functionalities through control of strain, defect, and interface is summarized.
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Affiliation(s)
- Aiping Chen
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Qing Su
- Nebraska Center for Energy Sciences Research, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA
| | - Hyungkyu Han
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Erik Enriquez
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Quanxi Jia
- Department of Materials Design and Innovation, University at Buffalo-The State University of New York, Buffalo, NY, 14260, USA
- Division of Quantum Phases and Devices, Department of Physics, Konkuk University, Seoul, 143-701, South Korea
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11
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Itinerant ferromagnetism of the Pd-terminated polar surface of PdCoO 2. Proc Natl Acad Sci U S A 2018; 115:12956-12960. [PMID: 30514820 DOI: 10.1073/pnas.1811873115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ability to modulate the collective properties of correlated electron systems at their interfaces and surfaces underpins the burgeoning field of "designer" quantum materials. Here, we show how an electronic reconstruction driven by surface polarity mediates a Stoner-like magnetic instability to itinerant ferromagnetism at the Pd-terminated surface of the nonmagnetic delafossite oxide metal PdCoO2 Combining angle-resolved photoemission spectroscopy and density-functional theory calculations, we show how this leads to a rich multiband surface electronic structure. We find similar surface state dispersions in PdCrO2, suggesting surface ferromagnetism persists in this sister compound despite its bulk antiferromagnetic order.
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12
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Eom CJ, Kuo DY, Adamo C, Moon EJ, May SJ, Crumlin EJ, Schlom DG, Suntivich J. Tailoring manganese oxide with atomic precision to increase surface site availability for oxygen reduction catalysis. Nat Commun 2018; 9:4034. [PMID: 30279490 PMCID: PMC6168596 DOI: 10.1038/s41467-018-06503-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 09/07/2018] [Indexed: 11/30/2022] Open
Abstract
Controlling the structure of catalysts at the atomic level provides an opportunity to establish detailed understanding of the catalytic form-to-function and realize new, non-equilibrium catalytic structures. Here, advanced thin-film deposition is used to control the atomic structure of La2/3Sr1/3MnO3, a well-known catalyst for the oxygen reduction reaction. The surface and sub-surface is customized, whereas the overall composition and d-electron configuration of the oxide is kept constant. Although the addition of SrMnO3 benefits the oxygen reduction reaction via electronic structure and conductivity improvements, SrMnO3 can react with ambient air to reduce the surface site availability. Placing SrMnO3 in the sub-surface underneath a LaMnO3 overlayer allows the catalyst to maintain the surface site availability while benefiting from improved electronic effects. The results show the promise of advanced thin-film deposition for realizing atomically precise catalysts, in which the surface and sub-surface structure and stoichiometry are tailored for functionality, over controlling only bulk compositions. Controlling structures at the atomic level provides an opportunity to design and understand catalysts. Here the authors use thin-film deposition to fabricate perovskite heterostructures in a non-equilibrium manner to assess the effects on electrocatalytic activity for oxygen reduction.
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Affiliation(s)
- C John Eom
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Ding-Yuan Kuo
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Carolina Adamo
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Eun Ju Moon
- Department of Materials Science and Engineering, Drexel University, Philadelphia, PA, 19104, USA
| | - Steve J May
- Department of Materials Science and Engineering, Drexel University, Philadelphia, PA, 19104, USA
| | - Ethan J Crumlin
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Darrell G Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA.,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, 14853, USA
| | - Jin Suntivich
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA. .,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, 14853, USA.
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13
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Wang Y, Huang MR, Salzberger U, Hahn K, Sigle W, van Aken PA. Towards atomically resolved EELS elemental and fine structure mapping via multi-frame and energy-offset correction spectroscopy. Ultramicroscopy 2018; 184:98-105. [DOI: 10.1016/j.ultramic.2017.10.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 10/16/2017] [Accepted: 10/20/2017] [Indexed: 11/28/2022]
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14
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Li L, Boullay P, Lu P, Wang X, Jian J, Huang J, Gao X, Misra S, Zhang W, Perez O, Steciuk G, Chen A, Zhang X, Wang H. Novel Layered Supercell Structure from Bi 2AlMnO 6 for Multifunctionalities. NANO LETTERS 2017; 17:6575-6582. [PMID: 28968496 DOI: 10.1021/acs.nanolett.7b02284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Layered materials, e.g., graphene and transition metal (di)chalcogenides, holding great promises in nanoscale device applications have been extensively studied in fundamental chemistry, solid state physics and materials research areas. In parallel, layered oxides (e.g., Aurivillius and Ruddlesden-Popper phases) present an attractive class of materials both because of their rich physics behind and potential device applications. In this work, we report a novel layered oxide material with self-assembled layered supercell structure consisting of two mismatch-layered sublattices of [Bi3O3+δ] and [MO2]1.84 (M = Al/Mn, simply named BAMO), i.e., alternative layered stacking of two mutually incommensurate sublattices made of a three-layer-thick Bi-O slab and a one-layer-thick Al/Mn-O octahedra slab in the out-of-plane direction. Strong room-temperature ferromagnetic and piezoelectric responses as well as anisotropic optical property have been demonstrated with great potentials in various device applications. The realization of the novel BAMO layered supercell structure in this work has paved an avenue toward exploring and designing new materials with multifunctionalities.
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Affiliation(s)
- Leigang Li
- School of Materials Engineering, Purdue University , West Lafayette, Indiana 47907, United States
- Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States
| | - Philippe Boullay
- Laboratoire de Cristallographie et Sciences des Matériaux (CRISMAT), Normandie Université, ENSICAEN, UNICAEN, CNRS UMR 6508, 6 Boulevard Maréchal Juin, F-14050 Caen Cedex 4, France
| | - Ping Lu
- Sandia National Laboratories , Albuquerque, New Mexico 87185, United States
| | - Xuejing Wang
- School of Materials Engineering, Purdue University , West Lafayette, Indiana 47907, United States
| | - Jie Jian
- School of Materials Engineering, Purdue University , West Lafayette, Indiana 47907, United States
| | - Jijie Huang
- School of Materials Engineering, Purdue University , West Lafayette, Indiana 47907, United States
| | - Xingyao Gao
- School of Materials Engineering, Purdue University , West Lafayette, Indiana 47907, United States
| | - Shikhar Misra
- School of Materials Engineering, Purdue University , West Lafayette, Indiana 47907, United States
| | - Wenrui Zhang
- Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States
| | - Olivier Perez
- Laboratoire de Cristallographie et Sciences des Matériaux (CRISMAT), Normandie Université, ENSICAEN, UNICAEN, CNRS UMR 6508, 6 Boulevard Maréchal Juin, F-14050 Caen Cedex 4, France
| | - Gwladys Steciuk
- Laboratoire de Cristallographie et Sciences des Matériaux (CRISMAT), Normandie Université, ENSICAEN, UNICAEN, CNRS UMR 6508, 6 Boulevard Maréchal Juin, F-14050 Caen Cedex 4, France
| | - Aiping Chen
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Xinghang Zhang
- School of Materials Engineering, Purdue University , West Lafayette, Indiana 47907, United States
| | - Haiyan Wang
- School of Materials Engineering, Purdue University , West Lafayette, Indiana 47907, United States
- Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States
- Department of Electrical and Computer Engineering, Texas A&M University , College Station, Texas 77843, United States
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15
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Ramasse QM. Twenty years after: How “Aberration correction in the STEM” truly placed a “A synchrotron in a Microscope”. Ultramicroscopy 2017; 180:41-51. [DOI: 10.1016/j.ultramic.2017.03.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 03/06/2017] [Accepted: 03/14/2017] [Indexed: 10/19/2022]
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16
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Chen H, Millis A. Charge transfer driven emergent phenomena in oxide heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:243001. [PMID: 28437253 DOI: 10.1088/1361-648x/aa6efe] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Complex oxides exhibit many intriguing phenomena, including metal-insulator transition, ferroelectricity/multiferroicity, colossal magnetoresistance and high transition temperature superconductivity. Advances in epitaxial thin film growth techniques enable us to combine different complex oxides with atomic precision and form an oxide heterostructure. Recent theoretical and experimental work has shown that charge transfer across oxide interfaces generally occurs and leads to a great diversity of emergent interfacial properties which are not exhibited by bulk constituents. In this report, we review mechanisms and physical consequence of charge transfer across interfaces in oxide heterostructures. Both theoretical proposals and experimental measurements of various oxide heterostructures are discussed and compared. We also review the theoretical methods that are used to calculate charge transfer across oxide interfaces and discuss the success and challenges in theory. Finally, we present a summary and perspectives for future research.
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Affiliation(s)
- Hanghui Chen
- NYU-ECNU Institute of Physics, New York University Shanghai, 200062, People's Republic of China. Department of Physics, New York University, New York, NY 10002, United States of America
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17
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Pham A, Li S. Engineering the strongly correlated properties of bulk Ruddlesden-Popper transition metal oxides via self-doping. Phys Chem Chem Phys 2017; 19:11373-11379. [PMID: 28422209 DOI: 10.1039/c7cp01700f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We demonstrate via first-principles calculations a novel method of tuning the electron-electron interactions in bulk oxide materials via controlling the cationic layer arrangement. Using the Ruddlesden-Popper oxides LaSrMnO4 and LaSrTiO4 as examples, our study demonstrates that a self-doping effect can be induced by changing the stacking of the neutral and charged cationic layers. It is believed that such a phenomenon is associated with different movements of apical oxygen atoms, resulting in diverse bandgaps, magnetism and orbital degrees of freedom in the same stoichiometric strongly-correlated material. This finding may open up a new direction to engineer the transition metal oxides for practical applications requiring tunable electronic properties without external doping.
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Affiliation(s)
- Anh Pham
- School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
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18
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Atomic-scale control of magnetic anisotropy via novel spin-orbit coupling effect in La2/3Sr1/3MnO3/SrIrO3 superlattices. Proc Natl Acad Sci U S A 2016; 113:6397-402. [PMID: 27199482 DOI: 10.1073/pnas.1524689113] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Magnetic anisotropy (MA) is one of the most important material properties for modern spintronic devices. Conventional manipulation of the intrinsic MA, i.e., magnetocrystalline anisotropy (MCA), typically depends upon crystal symmetry. Extrinsic control over the MA is usually achieved by introducing shape anisotropy or exchange bias from another magnetically ordered material. Here we demonstrate a pathway to manipulate MA of 3d transition-metal oxides (TMOs) by digitally inserting nonmagnetic 5d TMOs with pronounced spin-orbit coupling (SOC). High-quality superlattices comprising ferromagnetic La2/3Sr1/3MnO3 (LSMO) and paramagnetic SrIrO3 (SIO) are synthesized with the precise control of thickness at the atomic scale. Magnetic easy-axis reorientation is observed by controlling the dimensionality of SIO, mediated through the emergence of a novel spin-orbit state within the nominally paramagnetic SIO.
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19
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Wang XR, Li CJ, Lu WM, Paudel TR, Leusink DP, Hoek M, Poccia N, Vailionis A, Venkatesan T, Coey JMD, Tsymbal EY, Ariando, Hilgenkamp H. Imaging and control of ferromagnetism in LaMnO3/SrTiO3 heterostructures. Science 2015; 349:716-9. [DOI: 10.1126/science.aaa5198] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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20
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Disa AS, Kumah DP, Malashevich A, Chen H, Arena DA, Specht ED, Ismail-Beigi S, Walker FJ, Ahn CH. Orbital engineering in symmetry-breaking polar heterostructures. PHYSICAL REVIEW LETTERS 2015; 114:026801. [PMID: 25635555 DOI: 10.1103/physrevlett.114.026801] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Indexed: 05/21/2023]
Abstract
We experimentally demonstrate a novel approach to substantially modify orbital occupations and symmetries in electronically correlated oxides. In contrast to methods using strain or confinement, this orbital tuning is achieved by exploiting charge transfer and inversion symmetry breaking using atomically layered heterostructures. We illustrate the technique in the LaTiO_{3}-LaNiO_{3}-LaAlO_{3} system; a combination of x-ray absorption spectroscopy and ab initio theory reveals electron transfer and concomitant polar fields, resulting in a ∼50% change in the occupation of Ni d orbitals. This change is sufficiently large to remove the orbital degeneracy of bulk LaNiO_{3} and creates an electronic configuration approaching a single-band Fermi surface. Furthermore, we theoretically show that such three-component heterostructuring is robust and tunable by choice of insulator in the heterostructure, providing a general method for engineering orbital configurations and designing novel electronic systems.
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Affiliation(s)
- Ankit S Disa
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Divine P Kumah
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Andrei Malashevich
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Hanghui Chen
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA and Department of Physics, Columbia University, New York, New York 10027, USA and Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
| | - Dario A Arena
- National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Eliot D Specht
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Sohrab Ismail-Beigi
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA and Departments of Physics and Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA
| | - F J Walker
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Charles H Ahn
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA and Departments of Physics and Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA
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21
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A Minimal tight-binding model for ferromagnetic canted bilayer manganites. Sci Rep 2014; 4:7512. [PMID: 25522737 PMCID: PMC4271262 DOI: 10.1038/srep07512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 11/20/2014] [Indexed: 11/25/2022] Open
Abstract
Half-metallicity in materials has been a subject of extensive research due to its potential for applications in spintronics. Ferromagnetic manganites have been seen as a good candidate, and aside from a small minority-spin pocket observed in La2−2xSr1+2xMn2O7 (x = 0.38), transport measurements show that ferromagnetic manganites essentially behave like half metals. Here we develop robust tight-binding models to describe the electronic band structure of the majority as well as minority spin states of ferromagnetic, spin-canted antiferromagnetic, and fully antiferromagnetic bilayer manganites. Both the bilayer coupling between the MnO2 planes and the mixing of the |x2 − y2 > and |3z2 − r2 > Mn 3d orbitals play an important role in the subtle behavior of the bilayer splitting. Effects of kz dispersion are included.
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22
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Moon EJ, Colby R, Wang Q, Karapetrova E, Schlepütz CM, Fitzsimmons MR, May SJ. Spatial control of functional properties via octahedral modulations in complex oxide superlattices. Nat Commun 2014; 5:5710. [DOI: 10.1038/ncomms6710] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/29/2014] [Indexed: 11/09/2022] Open
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23
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Mundy JA, Hikita Y, Hidaka T, Yajima T, Higuchi T, Hwang HY, Muller DA, Kourkoutis LF. Visualizing the interfacial evolution from charge compensation to metallic screening across the manganite metal-insulator transition. Nat Commun 2014; 5:3464. [PMID: 24632721 DOI: 10.1038/ncomms4464] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 02/18/2014] [Indexed: 11/09/2022] Open
Abstract
Electronic changes at polar interfaces between transition metal oxides offer the tantalizing possibility to stabilize novel ground states yet can also cause unintended reconstructions in devices. The nature of these interfacial reconstructions should be qualitatively different for metallic and insulating films as the electrostatic boundary conditions and compensation mechanisms are distinct. Here we directly quantify with atomic-resolution the charge distribution for manganite-titanate interfaces traversing the metal-insulator transition. By measuring the concentration and valence of the cations, we find an intrinsic interfacial electronic reconstruction in the insulating films. The total charge observed for the insulating manganite films quantitatively agrees with that needed to cancel the polar catastrophe. As the manganite becomes metallic with increased hole doping, the total charge build-up and its spatial range drop substantially. Direct quantification of the intrinsic charge transfer and spatial width should lay the framework for devices harnessing these unique electronic phases.
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Affiliation(s)
- Julia A Mundy
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Takeaki Hidaka
- Department of Advanced Materials Science, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Takeaki Yajima
- 1] Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA [2] Department of Materials Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Takuya Higuchi
- Department of Advanced Materials Science, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Harold Y Hwang
- 1] Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA [2] Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - David A Muller
- 1] School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA [2] Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| | - Lena F Kourkoutis
- 1] School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA [2] Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
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24
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Tian H, Verbeeck J, Brück S, Paul M, Kufer D, Sing M, Claessen R, Tendeloo GV. Interface-induced modulation of charge and polarization in thin film Fe(3)O(4). ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:461-465. [PMID: 24167041 DOI: 10.1002/adma.201303329] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 09/02/2013] [Indexed: 06/02/2023]
Abstract
Charge and polarization modulations in Fe3 O4 are controlled by taking advantage of interfacial strain effects. The feasibility of oxidation state control by strain modification is demonstrated and it is shown that this approach offers a stable configuration at room temperature. Direct evidence of how a local strain field changes the atomic coordination and introduces atomic displacements leading to polarization of Fe ions is presented.
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Affiliation(s)
- He Tian
- EMAT, Electron Microscopy for Materials Science, University of Antwerp, Belgium
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25
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Snijders PC, Gao M, Guo H, Cao G, Siemons W, Gao H, Ward TZ, Shen J, Gai Z. A persistent metal-insulator transition at the surface of an oxygen-deficient, epitaxial manganite film. NANOSCALE 2013; 5:9659-9665. [PMID: 23979041 DOI: 10.1039/c3nr02343e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The oxygen stoichiometry has a large influence on the physical and chemical properties of complex oxides. Most of the functionality in e.g. catalysis and electrochemistry depends in particular on control of the oxygen stoichiometry. In order to understand the fundamental properties of intrinsic surfaces of oxygen-deficient complex oxides, we report on in situ temperature dependent scanning tunnelling spectroscopy experiments on pristine oxygen deficient, epitaxial manganite films. Although these films are insulating in subsequent ex situ in-plane electronic transport experiments at all temperatures, in situ scanning tunnelling spectroscopic data reveal that the surface of these films exhibits a metal-insulator transition (MIT) at 120 K, coincident with the onset of ferromagnetic ordering of small clusters in the bulk of the oxygen-deficient film. The surprising proximity of the surface MIT transition temperature of nonstoichiometric films with that of the fully oxygenated bulk suggests that the electronic properties in the surface region are not significantly affected by oxygen deficiency in the bulk. This carries important implications for the understanding and functional design of complex oxides and their interfaces with specific electronic properties in catalysis, oxide electronics and electrochemistry.
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Affiliation(s)
- Paul C Snijders
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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26
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Chen H, Millis AJ, Marianetti CA. Engineering correlation effects via artificially designed oxide superlattices. PHYSICAL REVIEW LETTERS 2013; 111:116403. [PMID: 24074110 DOI: 10.1103/physrevlett.111.116403] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Indexed: 06/02/2023]
Abstract
Ab initio calculations are used to predict that a superlattice composed of layers of LaTiO3 and LaNiO3 alternating along the [001] direction is a S=1 Mott insulator with large magnetic moments on the Ni sites, negligible moments on the Ti sites and a charge transfer gap set by the energy difference between Ni d and Ti d states, distinct from conventional Mott insulators. Correlation effects are enhanced on the Ni sites via filling the oxygen p states and reducing the Ni-O-Ni bond angle. Small hole (electron) doping of the superlattice leads to a two-dimensional single-band situation with holes (electrons) residing on the Ni d(x2-y2) (Ti d(xy)) orbital and coupled to antiferromagnetically correlated spins in the NiO2 layer.
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Affiliation(s)
- Hanghui Chen
- Department of Physics, Columbia University, New York, New York 10027, USA and Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
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27
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Simultaneous EELS/EDS Composition Mapping at Atomic Resolution Using Fast STEM Spectrum-Imaging. ACTA ACUST UNITED AC 2013. [DOI: 10.1017/s1551929513000643] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
With advancements in aberration-corrected electron optics, the resolution in scanning transmission electron microscopy (STEM) has been significantly improved. More importantly, the reduction of the probe size and the increase of the probe current density enable the acquisition of elemental maps at the atomic scale in a fast manner using both EELS and EDS. With the latest generations of EELS spectrometers, atomic resolution compositional and chemical maps allow interfaces, oxidation state, and even single atoms to be examined with increasing detail. These improvements have also enabled elemental and chemical maps to be acquired rapidly using both low- and high-energy edges from elements across the periodic table, including heavy atoms such Au or Pt. On the EDS side, the introduction of large-area silicon drift detectors (SDD) has allowed these high-beam-current sources to be fully utilized. Improved detector area and support for higher count rates, compared to the previous generation of EDS detectors, allows the acquisition of EDS intensity maps from most types of material in the STEM, even for moderately thin samples. For the case of light elements, the reduced detector dead layer of SDD-based systems partially overcomes the very low florescence yield typical of low-energy X-ray lines. Also as reported in, atomic-level X-ray maps using fast detectors and bright sources can now be collected under some conditions. Because EDS and EELS provide complementary information about the sample, and are both generated with the electron beam, it would be wasteful to not acquire both datasets with every sample run.
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Miwa JA, Hofmann P, Simmons MY, Wells JW. Direct measurement of the band structure of a buried two-dimensional electron gas. PHYSICAL REVIEW LETTERS 2013; 110:136801. [PMID: 23581353 DOI: 10.1103/physrevlett.110.136801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Indexed: 06/02/2023]
Abstract
We directly measure the band structure of a buried two dimensional electron gas (2DEG) using angle resolved photoemission spectroscopy. The buried 2DEG forms 2 nm beneath the surface of p-type silicon, because of a dense delta-type layer of phosphorus n-type dopants which have been placed there. The position of the phosphorous layer is beyond the probing depth of the photoemission experiment but the observation of the 2DEG is nevertheless possible at certain photon energies where emission from the states is resonantly enhanced. This permits direct access to the band structure of the 2DEG and its temperature dependence.
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Affiliation(s)
- Jill A Miwa
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
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Song F, Monsen ÅF, Li ZS, Wells JW, Wahlström E. The layer-by-layer stoichiometry of La0.7
Sr0.3
MnO3
/SrTiO3
thin films and interfaces. SURF INTERFACE ANAL 2013. [DOI: 10.1002/sia.5240] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- F. Song
- Department of Physics; Norwegian University of Science and Technology (NTNU); Trondheim Norway
- Zernike Institute of Advanced Materials; University of Groningen; 9747 AG Groningen The Netherlands
| | - Å. F. Monsen
- Department of Physics; Norwegian University of Science and Technology (NTNU); Trondheim Norway
| | - Z. S. Li
- Institute for the Storage Ring Facilities; University of Aarhus; Aarhus Denmark
| | - J. W. Wells
- Department of Physics; Norwegian University of Science and Technology (NTNU); Trondheim Norway
- MAX IV Laboratory; Lund University; Lund Sweden
| | - E. Wahlström
- Department of Physics; Norwegian University of Science and Technology (NTNU); Trondheim Norway
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Rondinelli JM, May SJ. Oxide interfaces: Instrumental insights. NATURE MATERIALS 2012; 11:833-834. [PMID: 23001227 DOI: 10.1038/nmat3425] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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