1
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Stramaglia F, Panchal G, Nolting F, Vaz CAF. Fully Magnetically Polarized Ultrathin La 0.8Sr 0.2MnO 3 Films. ACS APPLIED MATERIALS & INTERFACES 2024; 16:4138-4149. [PMID: 38216138 PMCID: PMC10811626 DOI: 10.1021/acsami.3c14031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 12/18/2023] [Accepted: 12/18/2023] [Indexed: 01/14/2024]
Abstract
We report the observation of fully magnetically polarized ultrathin La0.8Sr0.2MnO3 films by using LaMnO3 and La0.45Sr0.55MnO3 buffer layers grown epitaxially on SrTiO3(001) substrates by molecular beam epitaxy. Specifically, we show that La0.8Sr0.2MnO3 films grown on 12-unit-cell LaMnO3 have bulk-like magnetic moments starting from a single unit cell thickness, while for the 15-unit-cell La0.45Sr0.55MnO3 buffer layer, the La0.8Sr0.2MnO3 transitions from an antiferromagnetic state to a fully spin-polarized ferromagnetic state at 4 unit cells. The magnetic results are confirmed by X-ray magnetic circular dichroism, while linear dichroic measurements carried out for the La0.8Sr0.2MnO3/La0.45Sr0.55MnO3 series show the presence of an orbital reorganization at the transition from the antiferromagnetic to ferromagnetic state corresponding to a change from a preferred in-plane orbital hole occupancy, characteristic of the A-type antiferromagnetic state of La0.45Sr0.55MnO3, to preferentially out of plane. We interpret our findings in terms of the different electronic charge transfers between the adjacent layers, confined to the unit cell in the case of insulating LaMnO3 and extended to a few unit cells in the case of conducting La0.45Sr0.55MnO3. Our work demonstrates an approach to growing ultrathin mixed-valence manganite films that are fully magnetically polarized from the single unit cell, paving the way to fully exploring the unique electronic properties of this class of strongly correlated oxide materials.
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Affiliation(s)
| | - Gyanendra Panchal
- Swiss Light Source, Paul Scherrer Institut, Villigen 5232, Switzerland
| | - Frithjof Nolting
- Swiss Light Source, Paul Scherrer Institut, Villigen 5232, Switzerland
| | - Carlos A. F. Vaz
- Swiss Light Source, Paul Scherrer Institut, Villigen 5232, Switzerland
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2
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Ji Z, Hu M, Xin HL. MnEdgeNet for accurate decomposition of mixed oxidation states for Mn XAS and EELS L2,3 edges without reference and calibration. Sci Rep 2023; 13:14132. [PMID: 37644034 PMCID: PMC10465522 DOI: 10.1038/s41598-023-40616-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 08/14/2023] [Indexed: 08/31/2023] Open
Abstract
Accurate decomposition of the mixed Mn oxidation states is highly important for characterizing the electronic structures, charge transfer and redox centers for electronic, and electrocatalytic and energy storage materials that contain Mn. Electron energy loss spectroscopy (EELS) and soft X-ray absorption spectroscopy (XAS) measurements of the Mn L2,3 edges are widely used for this purpose. To date, although the measurements of the Mn L2,3 edges are straightforward given the sample is prepared properly, an accurate decomposition of the mix valence states of Mn remains non-trivial. For both EELS and XAS, 2+, 3+, and 4+ reference spectra need to be taken on the same instrument/beamline and preferably in the same experimental session because the instrumental resolution and the energy axis offset could vary from one session to another. To circumvent this hurdle, in this study, we adopted a deep learning approach and developed a calibration-free and reference-free method to decompose the oxidation state of Mn L2,3 edges for both EELS and XAS. A deep learning regression model is trained to accurately predict the composition of the mix valence state of Mn. To synthesize physics-informed and ground-truth labeled training datasets, we created a forward model that takes into account plural scattering, instrumentation broadening, noise, and energy axis offset. With that, we created a 1.2 million-spectrum database with 1-by-3 oxidation state composition ground truth vectors. The library includes a sufficient variety of data including both EELS and XAS spectra. By training on this large database, our convolutional neural network achieves 85% accuracy on the validation dataset. We tested the model and found it is robust against noise (down to PSNR of 10) and plural scattering (up to t/λ = 1). We further validated the model against spectral data that were not used in training. In particular, the model shows high accuracy and high sensitivity for the decomposition of Mn3O4, MnO, Mn2O3, and MnO2. The accurate decomposition of Mn3O4 experimental data shows the model is quantitatively correct and can be deployed for real experimental data. Our model will not only be a valuable tool to researchers and material scientists but also can assist experienced electron microscopists and synchrotron scientists in the automated analysis of Mn L edge data.
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Affiliation(s)
- Zhengran Ji
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA, 92697, USA
| | - Mike Hu
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA, 92697, USA
| | - Huolin L Xin
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA, 92697, USA.
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3
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Goodge BH, Geisler B, Lee K, Osada M, Wang BY, Li D, Hwang HY, Pentcheva R, Kourkoutis LF. Resolving the polar interface of infinite-layer nickelate thin films. NATURE MATERIALS 2023; 22:466-473. [PMID: 36973543 DOI: 10.1038/s41563-023-01510-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/14/2023] [Indexed: 06/18/2023]
Abstract
Nickel-based superconductors provide a long-awaited experimental platform to explore possible cuprate-like superconductivity. Despite similar crystal structure and d electron filling, however, superconductivity in nickelates has thus far only been stabilized in thin-film geometry, raising questions about the polar interface between substrate and thin film. Here we conduct a detailed experimental and theoretical study of the prototypical interface between Nd1-xSrxNiO2 and SrTiO3. Atomic-resolution electron energy loss spectroscopy in the scanning transmission electron microscope reveals the formation of a single intermediate Nd(Ti,Ni)O3 layer. Density functional theory calculations with a Hubbard U term show how the observed structure alleviates the polar discontinuity. We explore the effects of oxygen occupancy, hole doping and cation structure to disentangle the contributions of each for reducing interface charge density. Resolving the non-trivial interface structure will be instructive for future synthesis of nickelate films on other substrates and in vertical heterostructures.
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Affiliation(s)
- Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA.
| | - Benjamin Geisler
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Duisburg, Germany
| | - Kyuho Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Motoki Osada
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Bai Yang Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Danfeng Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, USA
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Rossitza Pentcheva
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Duisburg, Germany
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA.
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4
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De Luca G, Spring J, Kaviani M, Jöhr S, Campanini M, Zakharova A, Guillemard C, Herrero-Martin J, Erni R, Piamonteze C, Rossell MD, Aschauer U, Gibert M. Top-Layer Engineering Reshapes Charge Transfer at Polar Oxide Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2203071. [PMID: 35841137 DOI: 10.1002/adma.202203071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/12/2022] [Indexed: 06/15/2023]
Abstract
Charge-transfer phenomena at heterointerfaces are a promising pathway to engineer functionalities absent in bulk materials but can also lead to degraded properties in ultrathin films. Mitigating such undesired effects with an interlayer reshapes the interface architecture, restricting its operability. Therefore, developing less-invasive methods to control charge transfer will be beneficial. Here, an appropriate top-interface design allows for remote manipulation of the charge configuration of the buried interface and concurrent restoration of the ferromagnetic trait of the whole film. Double-perovskite insulating ferromagnetic La2 NiMnO6 (LNMO) thin films grown on perovskite oxide substrates are investigated as a model system. An oxygen-vacancy-assisted electronic reconstruction takes place initially at the LNMO polar interfaces. As a result, the magnetic properties of 2-5 unit cell LNMO films are affected beyond dimensionality effects. The introduction of a top electron-acceptor layer redistributes the electron excess and restores the ferromagnetic properties of the ultrathin LNMO films. Such a strategy can be extended to other interfaces and provides an advanced approach to fine-tune the electronic features of complex multilayered heterostructures.
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Affiliation(s)
- Gabriele De Luca
- Department of Physics, University of Zurich, Winterthurerstrasse 190, Zurich, 8057, Switzerland
| | - Jonathan Spring
- Department of Physics, University of Zurich, Winterthurerstrasse 190, Zurich, 8057, Switzerland
| | - Moloud Kaviani
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland
| | - Simon Jöhr
- Department of Physics, University of Zurich, Winterthurerstrasse 190, Zurich, 8057, Switzerland
| | - Marco Campanini
- Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf, 8600, Switzerland
| | - Anna Zakharova
- Swiss Light Source, Paul Scherrer Institut, Villigen, 5232, Switzerland
| | - Charles Guillemard
- ALBA Synchrotron Light Source, Carrer de la Llum 2-26, Cerdanyola del Vallès, 08290, Spain
| | - Javier Herrero-Martin
- ALBA Synchrotron Light Source, Carrer de la Llum 2-26, Cerdanyola del Vallès, 08290, Spain
| | - Rolf Erni
- Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf, 8600, Switzerland
| | | | - Marta D Rossell
- Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf, 8600, Switzerland
| | - Ulrich Aschauer
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland
| | - Marta Gibert
- Department of Physics, University of Zurich, Winterthurerstrasse 190, Zurich, 8057, Switzerland
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5
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Abstract
Copper-based (cuprate) oxides are not only the original but also one of the best-studied families of “high-temperature” superconductors. With nominally identical crystal structure and electron count, nickel-based (nickelate) compounds have been widely pursued for decades as a possible analog to the cuprates. The recent demonstration of superconductivity in nickelate thin films has provided an experimental platform to explore the possible connections between the copper- and nickel-based superconductors. Here, we perform highly localized spectroscopic measurements to reveal a number of key differences between the two systems, particularly with regard to the hybridization between the O and metal (Cu or Ni) orbitals. The recent observation of superconductivity in Nd0.8Sr0.2NiO2 has raised fundamental questions about the hierarchy of the underlying electronic structure. Calculations suggest that this system falls in the Mott–Hubbard regime, rather than the charge-transfer configuration of other nickel oxides and the superconducting cuprates. Here, we use state-of-the-art, locally resolved electron energy-loss spectroscopy to directly probe the Mott–Hubbard character of Nd1−xSrxNiO2. Upon doping, we observe emergent hybridization reminiscent of the Zhang–Rice singlet via the oxygen-projected states, modification of the Nd 5d states, and the systematic evolution of Ni 3d hybridization and filling. These experimental data provide direct evidence for the multiband electronic structure of the superconducting infinite-layer nickelates, particularly via the effects of hole doping on not only the oxygen but also nickel and rare-earth bands.
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Possinger AR, Zachman MJ, Enders A, Levin BDA, Muller DA, Kourkoutis LF, Lehmann J. Organo-organic and organo-mineral interfaces in soil at the nanometer scale. Nat Commun 2020; 11:6103. [PMID: 33257711 PMCID: PMC7705750 DOI: 10.1038/s41467-020-19792-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 10/30/2020] [Indexed: 01/07/2023] Open
Abstract
The capacity of soil as a carbon (C) sink is mediated by interactions between organic matter and mineral phases. However, previously proposed layered accumulation of organic matter within aggregate organo-mineral microstructures has not yet been confirmed by direct visualization at the necessary nanometer-scale spatial resolution. Here, we identify disordered micrometer-size organic phases rather than previously reported ordered gradients in C functional groups. Using cryo-electron microscopy with electron energy loss spectroscopy (EELS), we show organo-organic interfaces in contrast to exclusively organo-mineral interfaces. Single-digit nanometer-size layers of C forms were detected at the organo-organic interface, showing alkyl C and nitrogen (N) enrichment (by 4 and 7%, respectively). At the organo-mineral interface, 88% (72-92%) and 33% (16-53%) enrichment of N and oxidized C, respectively, indicate different stabilization processes than at organo-organic interfaces. However, N enrichment at both interface types points towards the importance of N-rich residues for greater C sequestration.
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Affiliation(s)
- Angela R Possinger
- Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
- Department of Forest Resources and Environmental Conservation, Virginia Tech, Cheatham Hall, Blacksburg, VA, 24060, USA
| | - Michael J Zachman
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Akio Enders
- Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Barnaby D A Levin
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, 14853, USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, 14853, USA
| | - Johannes Lehmann
- Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA.
- Institute for Advanced Study, Technical University of Munich, Garching, Germany.
- Cornell Atkinson Center for Sustainability, Ithaca, NY, 14853, USA.
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7
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Wang H, Srot V, Jiang X, Yi M, Wang Y, Boschker H, Merkle R, Stark RW, Mannhart J, van Aken PA. Probing Charge Accumulation at SrMnO 3/SrTiO 3 Heterointerfaces via Advanced Electron Microscopy and Spectroscopy. ACS NANO 2020; 14:12697-12707. [PMID: 32910642 PMCID: PMC7596774 DOI: 10.1021/acsnano.0c01545] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 09/10/2020] [Indexed: 06/11/2023]
Abstract
The last three decades have seen a growing trend toward studying the interfacial phenomena in complex oxide heterostructures. Of particular concern is the charge distribution at interfaces, which is a crucial factor in controlling the interface transport behavior. However, the study of the charge distribution is very challenging due to its small length scale and the intricate structure and chemistry at interfaces. Furthermore, the underlying origin of the interfacial charge distribution has been rarely studied in-depth and is still poorly understood. Here, by a combination of aberration-corrected scanning transmission electron microscopy (STEM) and spectroscopy techniques, we identify the charge accumulation in the SrMnO3 (SMO) side of SrMnO3/SrTiO3 heterointerfaces and find that the charge density attains the maximum of 0.13 ± 0.07 e-/unit cell (uc) at the first SMO monolayer. Based on quantitative atomic-scale STEM analyses and first-principle calculations, we explore the origin of interfacial charge accumulation in terms of epitaxial strain-favored oxygen vacancies, cationic interdiffusion, interfacial charge transfer, and space-charge effects. This study, therefore, provides a comprehensive description of the charge distribution and related mechanisms at the SMO/STO heterointerfaces, which is beneficial for the functionality manipulation via charge engineering at interfaces.
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Affiliation(s)
- Hongguang Wang
- Max
Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Vesna Srot
- Max
Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Xijie Jiang
- Institute
of Materials Science, Technische Universität
Darmstadt, 64287 Darmstadt, Germany
| | - Min Yi
- Institute
of Materials Science, Technische Universität
Darmstadt, 64287 Darmstadt, Germany
- State
Key Lab of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics
(NUAA), Nanjing 210016, China
| | - Yi Wang
- Max
Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Hans Boschker
- Max
Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Rotraut Merkle
- Max
Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Robert W. Stark
- Institute
of Materials Science, Technische Universität
Darmstadt, 64287 Darmstadt, Germany
| | - Jochen Mannhart
- Max
Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Peter A. van Aken
- Max
Planck Institute for Solid State Research, 70569 Stuttgart, Germany
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8
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Zachman MJ, Hachtel JA, Idrobo JC, Chi M. Emerging Electron Microscopy Techniques for Probing Functional Interfaces in Energy Materials. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201902993] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Michael J. Zachman
- Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Jordan A. Hachtel
- Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Juan Carlos Idrobo
- Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Miaofang Chi
- Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge TN 37831 USA
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9
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Zachman MJ, Hachtel JA, Idrobo JC, Chi M. Emerging Electron Microscopy Techniques for Probing Functional Interfaces in Energy Materials. Angew Chem Int Ed Engl 2019; 59:1384-1396. [PMID: 31081976 DOI: 10.1002/anie.201902993] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 05/01/2019] [Indexed: 11/10/2022]
Abstract
Interfaces play a fundamental role in many areas of chemistry. However, their localized nature requires characterization techniques with high spatial resolution in order to fully understand their structure and properties. State-of-the-art atomic resolution or in situ scanning transmission electron microscopy and electron energy-loss spectroscopy are indispensable tools for characterizing the local structure and chemistry of materials with single-atom resolution, but they are not able to measure many properties that dictate function, such as vibrational modes or charge transfer, and are limited to room-temperature samples containing no liquids. Here, we outline emerging electron microscopy techniques that are allowing these limitations to be overcome and highlight several recent studies that were enabled by these techniques. We then provide a vision for how these techniques can be paired with each other and with in situ methods to deliver new insights into the static and dynamic behavior of functional interfaces.
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Affiliation(s)
- Michael J Zachman
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Jordan A Hachtel
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Juan Carlos Idrobo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Miaofang Chi
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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10
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Li M, Tang C, Paudel TR, Song D, Lü W, Han K, Huang Z, Zeng S, Renshaw Wang X, Yang P, Chen J, Venkatesan T, Tsymbal EY, Li C, Pennycook SJ. Controlling the Magnetic Properties of LaMnO 3 /SrTiO 3 Heterostructures by Stoichiometry and Electronic Reconstruction: Atomic-Scale Evidence. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1901386. [PMID: 31099075 DOI: 10.1002/adma.201901386] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/10/2019] [Indexed: 06/09/2023]
Abstract
Interface-driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking are of importance for fundamental physics and device applications. How interfaces affect the interplay between charge, spin, orbital, and lattice degrees of freedom is the key to boosting device performance. In LaMnO3 /SrTiO3 (LMO/STO) polar-nonpolar heterostructures, electronic reconstruction leads to an antiferromagnetic to ferromagnetic transition, making them viable for spin filter applications. The interfacial electronic structure plays a critical role in the understanding of the microscopic origins of the observed magnetic phase transition, from antiferromagnetic at 5 unit cells (ucs) of LMO or below to ferromagnetic at 6 ucs or above, yet such a study is missing. Here, an atomic scale understanding of LMO/STO ambipolar ferromagnetism is offered by quantifying the interface charge distribution and performing first-principles density functional theory (DFT) calculations across this abrupt magnetic transition. It is found that the electronic reconstruction is confined within the first 3 ucs of LMO from the interface, and more importantly, it is robust against oxygen nonstoichiometry. When restoring stoichiometry, an enhanced ferromagnetic insulating state in LMO films with a thickness as thin as 2 nm (5 uc) is achieved, making LMO readily applicable as barriers in spin filters.
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Affiliation(s)
- Mengsha Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Chunhua Tang
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Tula R Paudel
- Department of Physics and Astronomy and Nebraska, Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, 68588, USA
| | - Dongsheng Song
- NUSNNI-Nanocore, National University of Singapore, Singapore, 117411, Singapore
| | - Weiming Lü
- Spintronics Institute, University of Jinan, Jinan, 250022, China
- Condensed Matter Science and Technology Institute and Department of Physics, Harbin Institute of Technology, Harbin, 150001, China
| | - Kun Han
- NUSNNI-Nanocore, National University of Singapore, Singapore, 117411, Singapore
| | - Zhen Huang
- NUSNNI-Nanocore, National University of Singapore, Singapore, 117411, Singapore
| | - Shengwei Zeng
- NUSNNI-Nanocore, National University of Singapore, Singapore, 117411, Singapore
| | - Xiao Renshaw Wang
- School of Physical and Mathematical Sciences and School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Ping Yang
- Singapore Synchrotron Light Source National University of Singapore 5 Research Link, Singapore, 117603, Singapore
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | | | - Evgeny Y Tsymbal
- Department of Physics and Astronomy and Nebraska, Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, 68588, USA
| | - Changjian Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Stephen John Pennycook
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
- NUSNNI-Nanocore, National University of Singapore, Singapore, 117411, Singapore
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11
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Atomic-scale determination of spontaneous magnetic reversal in oxide heterostructures. Proc Natl Acad Sci U S A 2019; 116:10309-10316. [PMID: 31068468 DOI: 10.1073/pnas.1819570116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interfaces between transition metal oxides are known to exhibit emerging electronic and magnetic properties. Here we report intriguing magnetic phenomena for La2/3Sr1/3MnO3 films on an SrTiO3 (001) substrate (LSMO/STO), where the interface governs the macroscopic properties of the entire monolithic thin film. The interface is characterized on the atomic level utilizing scanning transmission electron microscopy and electron energy loss spectroscopy (STEM-EELS), and density functional theory (DFT) is employed to elucidate the physics. STEM-EELS reveals mixed interfacial stoichiometry, subtle lattice distortions, and oxidation-state changes. Magnetic measurements combined with DFT calculations demonstrate that a unique form of antiferromagnetic exchange coupling appears at the interface, generating a novel exchange spring-type interaction that results in a remarkable spontaneous magnetic reversal of the entire ferromagnetic film, and an inverted magnetic hysteresis, persisting above room temperature. Formal oxidation states derived from electron spectroscopy data expose the fact that interfacial oxidation states are not consistent with nominal charge counting. The present work demonstrates the necessity of atomically resolved electron microscopy and spectroscopy for interface studies. Theory demonstrates that interfacial nonstoichiometry is an essential ingredient, responsible for the observed physical properties. The DFT-calculated electrostatic potential is flat in both the LSMO and STO sides (no internal electric field) for both Sr-rich and stoichiometric interfaces, while the DFT-calculated charge density reveals no charge transfer/accumulation at the interface, indicating that oxidation-state changes do not necessarily reflect charge transfer and that the concept of polar mismatch is not applicable in metal-insulator polar-nonpolar interfaces.
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12
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Gan Y, Christensen DV, Zhang Y, Zhang H, Krishnan D, Zhong Z, Niu W, Carrad DJ, Norrman K, von Soosten M, Jespersen TS, Shen B, Gauquelin N, Verbeeck J, Sun J, Pryds N, Chen Y. Diluted Oxide Interfaces with Tunable Ground States. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1805970. [PMID: 30637817 DOI: 10.1002/adma.201805970] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/31/2018] [Indexed: 06/09/2023]
Abstract
The metallic interface between two oxide insulators, such as LaAlO3 /SrTiO3 (LAO/STO), provides new opportunities for electronics and spintronics. However, due to the presence of multiple orbital populations, tailoring the interfacial properties such as the ground state and metal-insulator transitions remains challenging. Here, an unforeseen tunability of the phase diagram of LAO/STO is reported by alloying LAO with a ferromagnetic LaMnO3 insulator without forming lattice disorder and at the same time without changing the polarity of the system. By increasing the Mn-doping level, x, of LaAl1- x Mnx O3 /STO (0 ≤ x ≤ 1), the interface undergoes a Lifshitz transition at x = 0.225 across a critical carrier density of nc = 2.8 × 1013 cm-2 , where a peak TSC ≈255 mK of superconducting transition temperature is observed. Moreover, the LaAl1- x Mnx O3 turns ferromagnetic at x ≥ 0.25. Remarkably, at x = 0.3, where the metallic interface is populated by only dxy electrons and just before it becomes insulating, a same device with both signatures of superconductivity and clear anomalous Hall effect (7.6 × 1012 cm-2 < ns ≤ 1.1 × 1013 cm-2 ) is achieved reproducibly. This provides a unique and effective way to tailor oxide interfaces for designing on-demand electronic and spintronic devices.
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Affiliation(s)
- Yulin Gan
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
| | - Dennis Valbjørn Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
| | - Yu Zhang
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
- National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hongrui Zhang
- National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Dileep Krishnan
- EMAT, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium
| | - Zhicheng Zhong
- Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
| | - Wei Niu
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
| | - Damon James Carrad
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Kion Norrman
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
| | - Merlin von Soosten
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Thomas Sand Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Baogen Shen
- National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Nicolas Gauquelin
- EMAT, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium
| | - Johan Verbeeck
- EMAT, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium
| | - Jirong Sun
- National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
| | - Yunzhong Chen
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
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13
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Metal-to-Insulator Transition in Ultrathin Manganite Heterostructures. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9010144] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Thickness-driven phase transitions have been widely observed in many correlated transition metal oxides materials. One of the important topics is the thickness-driven metal to insulator transition in half-metal La2/3Sr1/3MnO3 (LSMO) thin films, which has attracted great attention in the past few decades. In this article, we review research on the nature of the metal-to-insulator (MIT) transition in LSMO ultrathin films. We discuss in detail the proposed mechanisms, the progress made up to date, and the key issues existing in understanding the related MIT. We also discuss MIT in other correlated oxide materials as a comparison that also has some implications for understanding the origin of MIT.
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14
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Electrostatic potential and valence modulation in La 0.7Sr 0.3MnO 3 thin films. Sci Rep 2018; 8:14313. [PMID: 30254275 PMCID: PMC6156561 DOI: 10.1038/s41598-018-32701-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 09/13/2018] [Indexed: 11/13/2022] Open
Abstract
The Mn valence in thin film La0.7Sr0.3MnO3 was studied as a function of film thickness in the range of 1–16 unit cells with a combination of non-destructive bulk and surface sensitive X-ray absorption spectroscopy techniques. Using a layer-by-layer valence model, it was found that while the bulk averaged valence hovers around its expected value of 3.3, a significant deviation occurs within several unit cells of the surface and interface. These results were supported by first principles calculations. The surface valence increases to up to Mn3.7+, whereas the interface valence reduces down to Mn2.5+. The change in valence from the expected bulk value is consistent with charge redistribution due to the polar discontinuity at the film-substrate interface. The comparison with theory employed here illustrates how this layer-by-layer valence evolves with film thickness and allows for a deeper understanding of the microscopic mechanisms at play in this effect. These results offer insight on how the two-dimensional electron gas is created in thin film oxide alloys and how the magnetic ordering is reduced with dimensionality.
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15
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Abstract
The nature of superconductivity in the dilute semiconductor SrTiO3 has remained an open question for more than 50 y. The extremely low carrier densities ([Formula: see text]-[Formula: see text] cm-3) at which superconductivity occurs suggest an unconventional origin of superconductivity outside of the adiabatic limit on which the Bardeen-Cooper-Schrieffer (BCS) and Migdal-Eliashberg (ME) theories are based. We take advantage of a newly developed method for engineering band alignments at oxide interfaces and access the electronic structure of Nb-doped SrTiO3, using high-resolution tunneling spectroscopy. We observe strong coupling to the highest-energy longitudinal optic (LO) phonon branch and estimate the doping evolution of the dimensionless electron-phonon interaction strength ([Formula: see text]). Upon cooling below the superconducting transition temperature ([Formula: see text]), we observe a single superconducting gap corresponding to the weak-coupling limit of BCS theory, indicating an order of magnitude smaller coupling ([Formula: see text]). These results suggest that despite the strong normal state interaction with electrons, the highest LO phonon does not provide a dominant contribution to pairing. They further demonstrate that SrTiO3 is an ideal system to probe superconductivity over a wide range of carrier density, adiabatic parameter, and electron-phonon coupling strength.
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16
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Zhang F, Wu B, Zhou G, Quan ZY, Xu XH. Increased Curie Temperature Induced by Orbital Ordering in La 0.67Sr 0.33MnO 3/BaTiO 3 Superlattices. NANOSCALE RESEARCH LETTERS 2018; 13:24. [PMID: 29344742 PMCID: PMC5772345 DOI: 10.1186/s11671-018-2441-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 01/09/2018] [Indexed: 06/07/2023]
Abstract
Recent theoretical studies indicated that the Curie temperature of perovskite manganite thin films can be increased by more than an order of magnitude by applying appropriate interfacial strain to control orbital ordering. In this work, we demonstrate that the regular intercalation of BaTiO3 layers between La0.67Sr0.33MnO3 layers effectively enhances ferromagnetic order and increases the Curie temperature of La0.67Sr0.33MnO3/BaTiO3 superlattices. The preferential orbital occupancy of eg(x 2 -y 2 ) in La0.67Sr0.33MnO3 layers induced by the tensile strain of BaTiO3 layers is identified by X-ray linear dichroism measurements. Our results reveal that controlling orbital ordering can effectively improve the Curie temperature of La0.67Sr0.33MnO3 films and that in-plane orbital occupancy is beneficial to the double exchange ferromagnetic coupling of thin-film samples. These findings create new opportunities for the design and control of magnetism in artificial structures and pave the way to a variety of novel magnetoelectronic applications that operate far above room temperature.
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Affiliation(s)
- Fei Zhang
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen, 041004 China
- Research Institute of Materials Science, Shanxi Normal University, Linfen, 041004 China
| | - Biao Wu
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen, 041004 China
- Research Institute of Materials Science, Shanxi Normal University, Linfen, 041004 China
- Suzhou Institute of Nano-Tech and Nano-Bionics, China Academy of Sciences, Suzhou, 215123 China
| | - Guowei Zhou
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen, 041004 China
- Research Institute of Materials Science, Shanxi Normal University, Linfen, 041004 China
| | - Zhi-Yong Quan
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen, 041004 China
- Research Institute of Materials Science, Shanxi Normal University, Linfen, 041004 China
| | - Xiao-Hong Xu
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen, 041004 China
- Research Institute of Materials Science, Shanxi Normal University, Linfen, 041004 China
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17
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Yi D, Lu N, Chen X, Shen S, Yu P. Engineering magnetism at functional oxides interfaces: manganites and beyond. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:443004. [PMID: 28745614 DOI: 10.1088/1361-648x/aa824d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The family of transition metal oxides (TMOs) is a large class of magnetic materials that has been intensively studied due to the rich physics involved as well as the promising potential applications in next generation electronic devices. In TMOs, the spin, charge, orbital and lattice are strongly coupled, and significant advances have been achieved to engineer the magnetism by different routes that manipulate these degrees of freedom. The family of manganites is a model system of strongly correlated magnetic TMOs. In this review, using manganites thin films and the heterostructures in conjunction with other TMOs as model systems, we review the recent progress of engineering magnetism in TMOs. We first discuss the role of the lattice that includes the epitaxial strain and the interface structural coupling. Then we look into the role of charge, focusing on the interface charge modulation. Having demonstrated the static effects, we continue to review the research on dynamical control of magnetism by electric field. Next, we review recent advances in heterostructures comprised of high T c cuprate superconductors and manganites. Following that, we discuss the emergent magnetic phenomena at interfaces between 3d TMOs and 5d TMOs with strong spin-orbit coupling. Finally, we provide our outlook for prospective future directions.
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Affiliation(s)
- Di Yi
- Geballe Laboratory for Advanced Materials and Applied Physics Department, Stanford University, Stanford, CA 94305, United States of America
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18
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Chen Z, Chen Z, Liu ZQ, Holtz ME, Li CJ, Wang XR, Lü WM, Motapothula M, Fan LS, Turcaud JA, Dedon LR, Frederick C, Xu RJ, Gao R, N'Diaye AT, Arenholz E, Mundy JA, Venkatesan T, Muller DA, Wang LW, Liu J, Martin LW. Electron Accumulation and Emergent Magnetism in LaMnO_{3}/SrTiO_{3} Heterostructures. PHYSICAL REVIEW LETTERS 2017; 119:156801. [PMID: 29077457 DOI: 10.1103/physrevlett.119.156801] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Indexed: 06/07/2023]
Abstract
Emergent phenomena at polar-nonpolar oxide interfaces have been studied intensely in pursuit of next-generation oxide electronics and spintronics. Here we report the disentanglement of critical thicknesses for electron reconstruction and the emergence of ferromagnetism in polar-mismatched LaMnO_{3}/SrTiO_{3} (001) heterostructures. Using a combination of element-specific x-ray absorption spectroscopy and dichroism, and first-principles calculations, interfacial electron accumulation, and ferromagnetism have been observed within the polar, antiferromagnetic insulator LaMnO_{3}. Our results show that the critical thickness for the onset of electron accumulation is as thin as 2 unit cells (UC), significantly thinner than the observed critical thickness for ferromagnetism of 5 UC. The absence of ferromagnetism below 5 UC is likely induced by electron overaccumulation. In turn, by controlling the doping of the LaMnO_{3}, we are able to neutralize the excessive electrons from the polar mismatch in ultrathin LaMnO_{3} films and thus enable ferromagnetism in films as thin as 3 UC, extending the limits of our ability to synthesize and tailor emergent phenomena at interfaces and demonstrating manipulation of the electronic and magnetic structures of materials at the shortest length scales.
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Affiliation(s)
- Zuhuang Chen
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Zhanghui Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Z Q Liu
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - M E Holtz
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - C J Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - X Renshaw Wang
- School of Physical and Mathematical Sciences & School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 637371, Singapore
| | - W M Lü
- Condensed Matter Science and Technology Institute, School of Science, Harbin Institute of Technology, Harbin 150081, People's Republic of China
| | - M Motapothula
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - L S Fan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J A Turcaud
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - L R Dedon
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - C Frederick
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - R J Xu
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - R Gao
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - A T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - E Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J A Mundy
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - T Venkatesan
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - D A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - L-W Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jian Liu
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - L W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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19
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Pincelli T, Lollobrigida V, Borgatti F, Regoutz A, Gobaut B, Schlueter C, Lee TL, Payne DJ, Oura M, Tamasaku K, Petrov AY, Graziosi P, Granozio FM, Cavallini M, Vinai G, Ciprian R, Back CH, Rossi G, Taguchi M, Daimon H, van der Laan G, Panaccione G. Quantifying the critical thickness of electron hybridization in spintronics materials. Nat Commun 2017; 8:16051. [PMID: 28714466 PMCID: PMC5520016 DOI: 10.1038/ncomms16051] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 05/15/2017] [Indexed: 11/09/2022] Open
Abstract
In the rapidly growing field of spintronics, simultaneous control of electronic and magnetic properties is essential, and the perspective of building novel phases is directly linked to the control of tuning parameters, for example, thickness and doping. Looking at the relevant effects in interface-driven spintronics, the reduced symmetry at a surface and interface corresponds to a severe modification of the overlap of electron orbitals, that is, to a change of electron hybridization. Here we report a chemically and magnetically sensitive depth-dependent analysis of two paradigmatic systems, namely La1−xSrxMnO3 and (Ga,Mn)As. Supported by cluster calculations, we find a crossover between surface and bulk in the electron hybridization/correlation and we identify a spectroscopic fingerprint of bulk metallic character and ferromagnetism versus depth. The critical thickness and the gradient of hybridization are measured, setting an intrinsic limit of 3 and 10 unit cells from the surface, respectively, for (Ga,Mn)As and La1−xSrxMnO3, for fully restoring bulk properties. Surface versus bulk effects in electronic structure of spintronics materials are crucial to their applications but are yet well understood. Here the authors experimentally determine the critical thickness that defines the crossover of electron hybridization between surface and bulk for two prototype spintronics materials.
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Affiliation(s)
- T Pincelli
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste I-34149, Italy.,Dipartimento di Fisica, Università di Milano, Via Celoria 16, Milano I-20133, Italy
| | - V Lollobrigida
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste I-34149, Italy.,Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, Roma I-00146, Italy
| | - F Borgatti
- Consiglio Nazionale delle Ricerche-Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), via P. Gobetti 101, Bologna I-40129, Italy
| | - A Regoutz
- Department of Materials, Imperial College London, South Kensington, London SW7 2AZ, UK
| | - B Gobaut
- Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, Area Science Park, Trieste 34149, Italy
| | - C Schlueter
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - T-L Lee
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - D J Payne
- Department of Materials, Imperial College London, South Kensington, London SW7 2AZ, UK
| | - M Oura
- RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - K Tamasaku
- RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - A Y Petrov
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste I-34149, Italy
| | - P Graziosi
- Consiglio Nazionale delle Ricerche-Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), via P. Gobetti 101, Bologna I-40129, Italy
| | - F Miletto Granozio
- CNR-SPIN, Complesso Universitario Monte S. Angelo, Napoli 80126, Italy.,Dipartimento di Fisica, Università 'Federico II' di Napoli, Napoli, 80126, Italy
| | - M Cavallini
- Consiglio Nazionale delle Ricerche-Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), via P. Gobetti 101, Bologna I-40129, Italy
| | - G Vinai
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste I-34149, Italy
| | - R Ciprian
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste I-34149, Italy
| | - C H Back
- Institut fur Experimentelle Physik, Universitat Regensburg, Regensburg D-93040, Germany
| | - G Rossi
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste I-34149, Italy.,Dipartimento di Fisica, Università di Milano, Via Celoria 16, Milano I-20133, Italy
| | - M Taguchi
- RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,Nara Institute of Science and Technology, 8-9165 Takayama, Ikoma, Nara 630-0192, Japan
| | - H Daimon
- Nara Institute of Science and Technology, 8-9165 Takayama, Ikoma, Nara 630-0192, Japan
| | - G van der Laan
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - G Panaccione
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste I-34149, Italy
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20
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Interface-induced multiferroism by design in complex oxide superlattices. Proc Natl Acad Sci U S A 2017; 114:E5062-E5069. [PMID: 28607082 DOI: 10.1073/pnas.1706814114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interfaces between materials present unique opportunities for the discovery of intriguing quantum phenomena. Here, we explore the possibility that, in the case of superlattices, if one of the layers is made ultrathin, unexpected properties can be induced between the two bracketing interfaces. We pursue this objective by combining advanced growth and characterization techniques with theoretical calculations. Using prototype La2/3Sr1/3MnO3 (LSMO)/BaTiO3 (BTO) superlattices, we observe a structural evolution in the LSMO layers as a function of thickness. Atomic-resolution EM and spectroscopy reveal an unusual polar structure phase in ultrathin LSMO at a critical thickness caused by interfacing with the adjacent BTO layers, which is confirmed by first principles calculations. Most important is the fact that this polar phase is accompanied by reemergent ferromagnetism, making this system a potential candidate for ultrathin ferroelectrics with ferromagnetic ordering. Monte Carlo simulations illustrate the important role of spin-lattice coupling in LSMO. These results open up a conceptually intriguing recipe for developing functional ultrathin materials via interface-induced spin-lattice coupling.
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21
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Guo EJ, Charlton T, Ambaye H, Desautels RD, Lee HN, Fitzsimmons MR. Orientation Control of Interfacial Magnetism at La 0.67Sr 0.33MnO 3/SrTiO 3 Interfaces. ACS APPLIED MATERIALS & INTERFACES 2017; 9:19307-19312. [PMID: 28509529 DOI: 10.1021/acsami.7b03252] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Understanding the magnetism at the interface between a ferromagnet and an insulator is essential because the commonly posited magnetic "dead" layer close to an interface can be problematic in magnetic tunnel junctions. Previously, degradation of the magnetic interface was attributed to charge discontinuity across the interface. Here, the interfacial magnetism was investigated using three identically prepared La0.67Sr0.33MnO3 (LSMO) thin films grown on different oriented SrTiO3 (STO) substrates by polarized neutron reflectometry. In all cases the magnetization at the LSMO/STO interface is larger than the film bulk. We show that the interfacial magnetization is largest across the LSMO/STO interfaces with (001) and (111) orientations, which have the largest net charge discontinuities across the interfaces. In contrast, the magnetization of LSMO/STO across the (110) interface, the orientation with no net charge discontinuity, is the smallest of the three orientations. We show that a magnetically degraded interface is not intrinsic to LSMO/STO heterostructures. The approach to use different crystallographic orientations provides a means to investigate the influence of charge discontinuity on the interfacial magnetization.
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Affiliation(s)
- Er-Jia Guo
- Quantum Condensed Matter Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Timothy Charlton
- Quantum Condensed Matter Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Haile Ambaye
- Instruments and Source Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Ryan D Desautels
- Quantum Condensed Matter Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Ho Nyung Lee
- Materials Science and Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Michael R Fitzsimmons
- Quantum Condensed Matter Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
- Department of Physics and Astronomy, University of Tennessee , Knoxville, Tennessee 37996, United States
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22
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Mundy JA, Schaab J, Kumagai Y, Cano A, Stengel M, Krug IP, Gottlob DM, Dog Anay H, Holtz ME, Held R, Yan Z, Bourret E, Schneider CM, Schlom DG, Muller DA, Ramesh R, Spaldin NA, Meier D. Functional electronic inversion layers at ferroelectric domain walls. NATURE MATERIALS 2017; 16:622-627. [PMID: 28319611 DOI: 10.1038/nmat4878] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 02/06/2017] [Indexed: 06/06/2023]
Abstract
Ferroelectric domain walls hold great promise as functional two-dimensional materials because of their unusual electronic properties. Particularly intriguing are the so-called charged walls where a polarity mismatch causes local, diverging electrostatic potentials requiring charge compensation and hence a change in the electronic structure. These walls can exhibit significantly enhanced conductivity and serve as a circuit path. The development of all-domain-wall devices, however, also requires walls with controllable output to emulate electronic nano-components such as diodes and transistors. Here we demonstrate electric-field control of the electronic transport at ferroelectric domain walls. We reversibly switch from resistive to conductive behaviour at charged walls in semiconducting ErMnO3. We relate the transition to the formation-and eventual activation-of an inversion layer that acts as the channel for the charge transport. The findings provide new insight into the domain-wall physics in ferroelectrics and foreshadow the possibility to design elementary digital devices for all-domain-wall circuitry.
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Affiliation(s)
- J A Mundy
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - J Schaab
- Department of Materials, ETH Zurich, 8093 Zürich, Switzerland
| | - Y Kumagai
- Department of Materials, ETH Zurich, 8093 Zürich, Switzerland
| | - A Cano
- CNRS, Université de Bordeaux, ICMCB, UPR 9048, 33600 Pessac, France
| | - M Stengel
- ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - I P Krug
- Institut für Optik und Atomare Physik, TU Berlin, 10623 Berlin, Germany
| | - D M Gottlob
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - H Dog Anay
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - M E Holtz
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - R Held
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Z Yan
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, ETH Zurich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - E Bourret
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C M Schneider
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - D G Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| | - D A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| | - R Ramesh
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Materials Science and Engineering and Department of Physics, UC Berkeley, Berkeley, California 94720, USA
| | - N A Spaldin
- Department of Materials, ETH Zurich, 8093 Zürich, Switzerland
| | - D Meier
- Department of Materials, ETH Zurich, 8093 Zürich, Switzerland
- Department of Materials Science and Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway
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23
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Li X, Lindfors-Vrejoiu I, Ziese M, Gloter A, van Aken PA. Impact of interfacial coupling of oxygen octahedra on ferromagnetic order in La 0.7Sr 0.3MnO 3/SrTiO 3 heterostructures. Sci Rep 2017; 7:40068. [PMID: 28074836 PMCID: PMC5225431 DOI: 10.1038/srep40068] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 11/30/2016] [Indexed: 11/09/2022] Open
Abstract
La0.7Sr0.3MnO3, a half-metallic ferromagnet with full spin polarization, is generally used as a standard spin injector in heterostructures. However, the magnetism of La0.7Sr0.3MnO3 is strongly modified near interfaces, which was addressed as "dead-layer" phenomenon whose origin is still controversial. Here, both magnetic and structural properties of La0.7Sr0.3MnO3/SrTiO3 heterostructures were investigated, with emphasis on the quantitative analysis of oxygen octahedral rotation (OOR) across interfaces using annular-bright-field imaging. OOR was found to be significantly altered near interface for both La0.7Sr0.3MnO3 and SrTiO3, as linked to the magnetism deterioration. Especially in La0.7Sr0.3MnO3/SrTiO3 superlattices, the almost complete suppression of OOR in 4 unit-cell-thick La0.7Sr0.3MnO3 results in a canted ferromagnetism. Detailed comparisons between strain and OOR relaxation and especially the observation of an unexpected La0.7Sr0.3MnO3 lattice c expansion near interfaces, prove the relevance of OOR for the magnetic properties. These results indicate the capability of tuning the magnetism by engineering OOR at the atomic scale.
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Affiliation(s)
- Xiaoyan Li
- Stuttgart Center for Electron Microscopy, Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.,Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris Sud, 91405 Orsay, France
| | | | - Michael Ziese
- Universität Leipzig, Fakultät für Physik und Geowissenschaften, Abteilung Supraleitung und Magnetismus, Linnéstrasse 5, D-04103 Leipzig, Germany
| | - Alexandre Gloter
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris Sud, 91405 Orsay, France
| | - Peter A van Aken
- Stuttgart Center for Electron Microscopy, Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
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24
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Chen B, Chen P, Xu H, Jin F, Guo Z, Lan D, Wan S, Gao G, Chen F, Wu W. Interfacial Control of Ferromagnetism in Ultrathin La 0.67Ca 0.33MnO 3 Sandwiched between CaRu 1-xTi xO 3 (x = 0-0.8) Epilayers. ACS APPLIED MATERIALS & INTERFACES 2016; 8:34924-34932. [PMID: 27936558 DOI: 10.1021/acsami.6b13158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Controlling functionalities in oxide heterostructures remains challenging for the rather complex interfacial interactions. Here, by modifying the interface properties with chemical doping, we achieve a nontrivial control over the ferromagnetism in ultrathin La0.67Ca0.33MnO3 (LCMO) layer sandwiched between CaRu1-xTixO3 [CRTO(x)] epilayers. The Ti doping suppresses the interfacial electron transfer from CRTO(x) to LCMO side; as a result, a steadily decreased Curie temperature with increasing x, from 262 K at x = 0 to 186 K at x = 0.8, is observed for the structures with LCMO fixed at 3.2 nm. Moreover, for more insulating CRTO(x ≥ 0.5), the electron confinement induces an interfacial Mn-eg(x2-y2) orbital order in LCMO which further attenuates the ferromagnetism. Also, in order to characterize the heterointerfaces, for the first time the doping- and thickness-dependent metal-insulator transitions in CRTO(x) films are examined. Our results demonstrate that the LCMO/CRTO(x) heterostructure could be a model system for investigating the interfacial multiple interactions in correlated oxides.
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Affiliation(s)
- Binbin Chen
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China , Hefei 230026, China
| | - Pingfan Chen
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China , Hefei 230026, China
| | - Haoran Xu
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China , Hefei 230026, China
| | - Feng Jin
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China , Hefei 230026, China
| | - Zhuang Guo
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China , Hefei 230026, China
| | - Da Lan
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China , Hefei 230026, China
| | - Siyuan Wan
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China , Hefei 230026, China
| | - Guanyin Gao
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China , Hefei 230026, China
| | - Feng Chen
- High Magnetic Field Laboratory, Chinese Academy of Sciences , Hefei 230031, China
| | - Wenbin Wu
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China , Hefei 230026, China
- High Magnetic Field Laboratory, Chinese Academy of Sciences , Hefei 230031, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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25
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Zachman MJ, Asenath-Smith E, Estroff LA, Kourkoutis LF. Site-Specific Preparation of Intact Solid-Liquid Interfaces by Label-Free In Situ Localization and Cryo-Focused Ion Beam Lift-Out. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2016; 22:1338-1349. [PMID: 27869059 DOI: 10.1017/s1431927616011892] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Scanning transmission electron microscopy (STEM) allows atomic scale characterization of solid-solid interfaces, but has seen limited applications to solid-liquid interfaces due to the volatility of liquids in the microscope vacuum. Although cryo-electron microscopy is routinely used to characterize hydrated samples stabilized by rapid freezing, sample thinning is required to access the internal interfaces of thicker specimens. Here, we adapt cryo-focused ion beam (FIB) "lift-out," a technique recently developed for biological specimens, to prepare intact internal solid-liquid interfaces for high-resolution structural and chemical analysis by cryo-STEM. To guide the milling process we introduce a label-free in situ method of localizing subsurface structures in suitable materials by energy dispersive X-ray spectroscopy (EDX). Monte Carlo simulations are performed to evaluate the depth-probing capability of the technique, and show good qualitative agreement with experiment. We also detail procedures to produce homogeneously thin lamellae, which enable nanoscale structural, elemental, and chemical analysis of intact solid-liquid interfaces by analytical cryo-STEM. This work demonstrates the potential of cryo-FIB lift-out and cryo-STEM for understanding physical and chemical processes at solid-liquid interfaces.
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Affiliation(s)
- Michael J Zachman
- 1School of Applied and Engineering Physics,Cornell University,Ithaca,NY 14853,USA
| | - Emily Asenath-Smith
- 3Department of Materials Science and Engineering,Cornell University,Ithaca,NY 14853,USA
| | - Lara A Estroff
- 2Kavli Institute at Cornell for Nanoscale Science,Cornell University,Ithaca,NY 14853,USA
| | - Lena F Kourkoutis
- 1School of Applied and Engineering Physics,Cornell University,Ithaca,NY 14853,USA
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26
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Li Z, Song D, Yu R, Ge B, Liao Z, Li Y, Dong S, Zhu J. Competing Interfacial Reconstruction Mechanisms in La0.7Sr0.3MnO3/SrTiO3 Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2016; 8:24192-24197. [PMID: 27551951 DOI: 10.1021/acsami.6b07569] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Interface coupling between complex oxides offers unique possibilities to tailor materials properties and stabilize novel ground states. Understanding the structural reconstruction of the corner-shared octahedral framework and the charge redistribution are crucial for controlling interfacial properties in oxide electronics. Here, we study the interfacial oxygen octahedral behavior in La0.7Sr0.3MnO3/SrTiO3 heterostructure, by directly imaging the oxygen octahedra at the atomic scale and extracting the structural parameters. We combine these experimental results with electronic structure calculations to elucidate the effect of reconstructed MnO6 octahedral geometry on increased interfacial magnetization and conductivity. The Mn valence profiles near the interface are quantitatively analyzed and compared at variant temperatures, revealing the insulating nature of interfacial manganite with reduced Mn valence. This study suggests a pathway to manipulate the interfacial properties and creation of new ground states in complex oxide heterostructures by tuning competing structural and electronic parameters.
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Affiliation(s)
- Zhipeng Li
- National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advanced Materials, Tsinghua University , Beijing 100084, China
| | - Dongsheng Song
- National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advanced Materials, Tsinghua University , Beijing 100084, China
| | - Rong Yu
- National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advanced Materials, Tsinghua University , Beijing 100084, China
| | - Binghui Ge
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences , Beijing 100190, China
| | - Zhenyu Liao
- National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advanced Materials, Tsinghua University , Beijing 100084, China
| | - Yueliang Li
- National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advanced Materials, Tsinghua University , Beijing 100084, China
| | - Shuai Dong
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Jing Zhu
- National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advanced Materials, Tsinghua University , Beijing 100084, China
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27
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Haruta M, Hosaka Y, Ichikawa N, Saito T, Shimakawa Y, Kurata H. Determination of Elemental Ratio in an Atomic Column by Electron Energy Loss Spectroscopy. ACS NANO 2016; 10:6680-6684. [PMID: 27341006 DOI: 10.1021/acsnano.6b01887] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Atomic-resolution quantification of the elemental ratio of Fe to Mn at the octahedral and tetrahedral sites in brownmillerite Ca2Fe1.07Mn0.93O5 was determined using electron energy-loss spectroscopy combined with aberration-corrected scanning transmission electron microscopy. The combined techniques revealed that oversampling of the spectral imaging data yielded a spatially resolved area that very nearly reflects atomic resolution (∼1.2 Å radius). The average experimental ratios of Fe to Mn within this region were 17.5:82.5 for the octahedral sites and 81.6:18.4 for the tetrahedral sites. The elemental ratio in an octahedral atomic column was successfully extracted by estimating the mixing of signals from nearest neighbor columns. The results indicated that the ratio of Fe to Mn was 13:87 at the octahedral site, which is in good agreement with the results of neutron diffraction analysis. In addition, the uncertainty of experimental results obtained by using an average 1.2 Å radius was less than 10% at octahedral sites, depending on the sample thickness. In contrast, the experimental error due to dechanneling of incident electrons was larger at the tetrahedral sites. This experimental procedure has wide application for determining the spatially resolved composition ratio of elements in perovskite-like compounds.
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Affiliation(s)
- Mitsutaka Haruta
- Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan
| | - Yoshiteru Hosaka
- Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan
| | - Noriya Ichikawa
- Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan
| | - Takashi Saito
- Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan
| | - Yuichi Shimakawa
- Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan
| | - Hiroki Kurata
- Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan
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28
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Gibert M, Viret M, Torres-Pardo A, Piamonteze C, Zubko P, Jaouen N, Tonnerre JM, Mougin A, Fowlie J, Catalano S, Gloter A, Stéphan O, Triscone JM. Interfacial Control of Magnetic Properties at LaMnO3/LaNiO3 Interfaces. NANO LETTERS 2015; 15:7355-7361. [PMID: 26484628 DOI: 10.1021/acs.nanolett.5b02720] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The functional properties of oxide heterostructures ultimately rely on how the electronic and structural mismatches occurring at interfaces are accommodated by the chosen materials combination. We discuss here LaMnO3/LaNiO3 heterostructures, which display an intrinsic interface structural asymmetry depending on the growth sequence. Using a variety of synchrotron-based techniques, we show that the degree of intermixing at the monolayer scale allows interface-driven properties such as charge transfer and the induced magnetic moment in the nickelate layer to be controlled. Further, our results demonstrate that the magnetic state of strained LaMnO3 thin films dramatically depends on interface reconstructions.
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Affiliation(s)
- M Gibert
- Département de Physique de la Matière Quantique, University of Geneva , Geneva, Switzerland
| | - M Viret
- Département de Physique de la Matière Quantique, University of Geneva , Geneva, Switzerland
- Service de Physique de l'Etat Condensé, CNRS URA 2464 , CEA Saclay, Gif-sur-Yvette, France
| | - A Torres-Pardo
- Laboratoire de Physique des Solides, University of Paris-Sud, CNRS-UMR 8502 , Orsay 91405, France
| | - C Piamonteze
- Swiss Light Source, Paul Scherrer Institute , 5232 Villigen-PSI, Switzerland
| | - P Zubko
- Département de Physique de la Matière Quantique, University of Geneva , Geneva, Switzerland
| | - N Jaouen
- Synchrotron SOLEIL , 91192 Gif-Sur-Yvette, France
| | | | - A Mougin
- Laboratoire de Physique des Solides, University of Paris-Sud, CNRS-UMR 8502 , Orsay 91405, France
| | - J Fowlie
- Département de Physique de la Matière Quantique, University of Geneva , Geneva, Switzerland
| | - S Catalano
- Département de Physique de la Matière Quantique, University of Geneva , Geneva, Switzerland
| | - A Gloter
- Laboratoire de Physique des Solides, University of Paris-Sud, CNRS-UMR 8502 , Orsay 91405, France
| | - O Stéphan
- Laboratoire de Physique des Solides, University of Paris-Sud, CNRS-UMR 8502 , Orsay 91405, France
| | - J-M Triscone
- Département de Physique de la Matière Quantique, University of Geneva , Geneva, Switzerland
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29
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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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30
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Marinova M, Rault JE, Gloter A, Nemsak S, Palsson GK, Rueff JP, Fadley CS, Carrétéro C, Yamada H, March K, Garcia V, Fusil S, Barthélémy A, Stéphan O, Colliex C, Bibes M. Depth profiling charge accumulation from a ferroelectric into a doped Mott insulator. NANO LETTERS 2015; 15:2533-2541. [PMID: 25768912 DOI: 10.1021/acs.nanolett.5b00104] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The electric field control of functional properties is a crucial goal in oxide-based electronics. Nonvolatile switching between different resistivity or magnetic states in an oxide channel can be achieved through charge accumulation or depletion from an adjacent ferroelectric. However, the way in which charge distributes near the interface between the ferroelectric and the oxide remains poorly known, which limits our understanding of such switching effects. Here, we use a first-of-a-kind combination of scanning transmission electron microscopy with electron energy loss spectroscopy, near-total-reflection hard X-ray photoemission spectroscopy, and ab initio theory to address this issue. We achieve a direct, quantitative, atomic-scale characterization of the polarization-induced charge density changes at the interface between the ferroelectric BiFeO3 and the doped Mott insulator Ca(1-x)Ce(x)MnO3, thus providing insight on how interface-engineering can enhance these switching effects.
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Affiliation(s)
- Maya Marinova
- †Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris Sud XI, 91405 Orsay, France
| | - Julien E Rault
- ‡Synchrotron-SOLEIL, BP 48, Saint-Aubin, F91192 Gif sur Yvette CEDEX, France
| | - Alexandre Gloter
- †Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris Sud XI, 91405 Orsay, France
| | - Slavomir Nemsak
- §Department of Physics, University of California Davis, Davis, California 95616, United States
- ∥Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- ⊥Peter Grünberg Institut PGI-6, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Gunnar K Palsson
- ∇Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala, Sweden
- #Institut Laue-Langevin, 38000 Grenoble, France
| | - Jean-Pascal Rueff
- ‡Synchrotron-SOLEIL, BP 48, Saint-Aubin, F91192 Gif sur Yvette CEDEX, France
| | - Charles S Fadley
- §Department of Physics, University of California Davis, Davis, California 95616, United States
- ∥Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Cécile Carrétéro
- ■Unité Mixte de Physique CNRS/Thales,1 Avenue A. Fresnel, 91767 Palaiseau, France and Université Paris-Sud, 91405 Orsay, France
| | - Hiroyuki Yamada
- ■Unité Mixte de Physique CNRS/Thales,1 Avenue A. Fresnel, 91767 Palaiseau, France and Université Paris-Sud, 91405 Orsay, France
- ▲National Institute of Advanced Industrial Science and Technology (AIST), JST, PRESTO, Tsukuba, Ibaraki 305-8562, Japan
| | - Katia March
- †Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris Sud XI, 91405 Orsay, France
| | - Vincent Garcia
- ■Unité Mixte de Physique CNRS/Thales,1 Avenue A. Fresnel, 91767 Palaiseau, France and Université Paris-Sud, 91405 Orsay, France
| | - Stéphane Fusil
- ■Unité Mixte de Physique CNRS/Thales,1 Avenue A. Fresnel, 91767 Palaiseau, France and Université Paris-Sud, 91405 Orsay, France
| | - Agnès Barthélémy
- ■Unité Mixte de Physique CNRS/Thales,1 Avenue A. Fresnel, 91767 Palaiseau, France and Université Paris-Sud, 91405 Orsay, France
| | - Odile Stéphan
- †Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris Sud XI, 91405 Orsay, France
| | - Christian Colliex
- †Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris Sud XI, 91405 Orsay, France
| | - Manuel Bibes
- ■Unité Mixte de Physique CNRS/Thales,1 Avenue A. Fresnel, 91767 Palaiseau, France and Université Paris-Sud, 91405 Orsay, France
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31
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Vaz CAF, Walker FJ, Ahn CH, Ismail-Beigi S. Intrinsic interfacial phenomena in manganite heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:123001. [PMID: 25721578 DOI: 10.1088/0953-8984/27/12/123001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We review recent advances in our understanding of interfacial phenomena that emerge when dissimilar materials are brought together at atomically sharp and coherent interfaces. In particular, we focus on phenomena that are intrinsic to the interface and review recent work carried out on perovskite manganites interfaces, a class of complex oxides whose rich electronic properties have proven to be a useful playground for the discovery and prediction of novel phenomena.
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Affiliation(s)
- C A F Vaz
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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