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Song D, Zheng F, Dunin-Borkowski RE. Prospect for measuring two-dimensional van der Waals magnets by electron magnetic chiral dichroism. Ultramicroscopy 2022; 234:113476. [PMID: 35114564 DOI: 10.1016/j.ultramic.2022.113476] [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: 11/01/2021] [Revised: 01/13/2022] [Accepted: 01/24/2022] [Indexed: 10/19/2022]
Abstract
Two-dimensional (2D) van der Waals magnets have drawn considerable attention in recent years triggered by the huge interest in novel magnetism and spintronic devices. Magnetic measurement of 2D van der Waals (vdW) magnets is crucial to understand the physical origin of magnetism in 2D limits. Therefore, advanced magnetic characterization techniques are highly required. However, only a limited number of such techniques are available due to the extremely small volume of 2D vdW magnets. Here, we introduce the electron magnetic chiral dichroism (EMCD) technique in transmission electron microscope (TEM) to measure 2D vdW crystals. In comparison with some other already-employed techniques in 2D magnets, EMCD is able to quantitatively measure magnetic parameters in three orthogonal directions at nanometer or even at atomic scale. We then perform EMCD simulations on several typical 2D vdW magnets with respect to the accelerating voltage, the number of atomic layers and beam tilt under zone axial orientation. The intensity and distribution of EMCD signals in three orthogonal directions are given in the diffraction plane, thereby providing an optimized design to achieve EMCD measurements. Finally, we discuss the signal-to-noise-ratio and required electron dose in order to obtain a measurable EMCD signal for 2D vdW magnets. Our results provide a feasibility analysis and guideline to measure 2D vdW magnets in future experiments.
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Affiliation(s)
- Dongsheng Song
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China; Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52425, Germany.
| | - Fengshan Zheng
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52425, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52425, Germany
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2
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Song D, Wang Z, Zhu J. Magnetic measurement by electron magnetic circular dichroism in the transmission electron microscope. Ultramicroscopy 2019; 201:1-17. [PMID: 30904784 DOI: 10.1016/j.ultramic.2019.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 03/05/2019] [Accepted: 03/18/2019] [Indexed: 10/27/2022]
Abstract
Magnetic measurement by transmitted electrons at nanometer or even atomic scale is always an attractive and challenging issue in the transmission electron microscope. Electron magnetic circular dichroism, proposed in 2003 and realized in 2006, opens a new insight into the measurement of local magnetic properties. Later, it is developed into a powerful technique for quantitative magnetic measurement with site specificity and element specificity at high spatial resolution over years of efforts, both in the aspect of theory and experiments. The novel technique has been widely applied to the characterization of magnetic materials now. This present review gives an overview of its development and applications in the past fifteen years since its invention. The theory of electron magnetic circular dichroism and its development are reviewed. The diffraction geometry and experimental setups are summarized. The general way for quantitative measurement of magnetic parameters is presented with typical cases. Representative breakthroughs in method development and applications over a wide range of materials are then described. Finally, prospects for future development are briefly discussed.
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Affiliation(s)
- Dongsheng Song
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
| | - Ziqiang Wang
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Jing Zhu
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
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3
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Chen X, Higashikozono S, Ito K, Jin L, Ho PL, Yu CP, Tai NH, Mayer J, Dunin-Borkowski RE, Suemasu T, Zhong X. Nanoscale measurement of giant saturation magnetization in α″-Fe 16N 2 by electron energy-loss magnetic chiral dichroism. Ultramicroscopy 2019; 203:37-43. [PMID: 30862364 DOI: 10.1016/j.ultramic.2019.02.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/10/2019] [Accepted: 02/18/2019] [Indexed: 10/27/2022]
Abstract
Metastable α″-Fe16N2 thin films were reported to have a giant saturation magnetization of above 2200 emu/cm3 in 1972 and have been considered as candidates for next-generation rare-earth-free permanent magnetic materials. However, their magnetic properties have not been confirmed unequivocally. As a result of the limited spatial resolution of most magnetic characterization techniques, it is challenging to measure the saturation magnetization of the α″-Fe16N2 phase, as it is often mixed with the parent α'-Fe8N phase in thin films. Here, we use electron energy-loss magnetic chiral dichroism (EMCD), aberration-corrected transmission electron microscopy, X-ray diffraction and macroscopic magnetic measurements to study α″-Fe16N2 (containing ordered N atoms) and α'-Fe8N (containing disordered N atoms). The ratio of saturation magnetization in α″-Fe16N2 to that in α'-Fe8N is determined to be 1.31 ± 0.10 from quantitative EMCD measurements and dynamical diffraction calculations, confirming the giant saturation magnetization of α″-Fe16N2. Crystallographic information is also obtained about the two phases, which are mixed on the nanoscale.
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Affiliation(s)
- Xinfeng Chen
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Soma Higashikozono
- Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Keita Ito
- Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Lei Jin
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, Jülich 52425, Germany
| | - Ping-Luen Ho
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Chu-Ping Yu
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 30013, Taiwan
| | - Nyan-Hwa Tai
- Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 30013, Taiwan
| | - Joachim Mayer
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, Jülich 52425, Germany; Central Facility for Electron Microscopy, RWTH Aachen University, Aachen 52074, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, Jülich 52425, Germany
| | - Takashi Suemasu
- Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Xiaoyan Zhong
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
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4
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Effect of cation ratio and order on magnetic circular dichroism in the double perovskite Sr 2Fe 1+xRe 1-xO 6. Ultramicroscopy 2018; 193:137-142. [PMID: 30005323 DOI: 10.1016/j.ultramic.2018.06.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 05/10/2018] [Accepted: 06/10/2018] [Indexed: 11/22/2022]
Abstract
Superexchange-based magnetic coupling of the two B-site cations in rock-salt-ordered double perovskite oxides is extremely sensitive to the cation ratio and degree of order. However, as a result of the limited spatial resolution of most magnetic characterization techniques, it is challenging to establish a direct relationship between magnetic properties and structure in these materials, including the effects of elemental segregation and cation disorder. Here, we use electron energy-loss magnetic chiral dichroism together with aberration-corrected electron microscopy and spectroscopy to record magnetic circular dichroism (MCD) spectra at the nm scale, in combination with structural and chemical information at the atomic scale from the very same region. We study nanoscale phases in ordered Sr2[Fe][Re]O6, ordered Sr2[Fe][Fe1/5Re4/5]O6 and disordered Sr[Fe4/5Re1/5]O3 individually, in order to understand the role of cation ratio and order on local magnetic coupling. When compared with ordered Sr2[Fe][Re]O6, we find that antiferromagnetic Fe3+-O2--Fe3+superexchange interactions arising from an excess of Fe suppress the MCD signal from Fe cations in ordered Sr2[Fe][Fe1/5Re4/5]O6, while dominant Fe3+-O2--Fe3+antiferromagnetic coupling in disordered Sr[Fe4/5Re1/5]O3 leads to a decrease in MCD signal down to the noise level. Our work demonstrates a protocol that can be used to correlate crystallographic, electronic and magnetic information in materials such as Sr2Fe1+xRe1-xO6, in order to provide insight into structure-property relationships in double perovskite oxides at the atomic scale.
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5
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Probing the localization of magnetic dichroism by atomic-size astigmatic and vortex electron beams. Sci Rep 2018; 8:4019. [PMID: 29507317 PMCID: PMC5838113 DOI: 10.1038/s41598-018-22234-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/15/2018] [Indexed: 12/04/2022] Open
Abstract
We report localization of a magnetic dichroic signal on atomic columns in electron magnetic circular dichroism (EMCD), probed by beam distorted by four-fold astigmatism and electron vortex beam. With astigmatic probe, magnetic signal to noise ratio can be enhanced by blocking the intensity from the central part of probe. However, the simulations show that for atomic resolution magnetic measurements, vortex beam is a more effective probe, with much higher magnetic signal to noise ratio. For all considered beam shapes, the optimal SNR constrains the signal detection at low collection angles of approximately 6–8 mrad. Irrespective of the material thickness, the magnetic signal remains strongly localized within the probed atomic column with vortex beam, whereas for astigmatic probes, the magnetic signal originates mostly from the nearest neighbor atomic columns. Due to excellent signal localization at probing individual atomic columns, vortex beams are predicted to be a strong candidate for studying the crystal site specific magnetic properties, magnetic properties at interfaces, or magnetism arising from individual atomic impurities.
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6
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An in-plane magnetic chiral dichroism approach for measurement of intrinsic magnetic signals using transmitted electrons. Nat Commun 2017; 8:15348. [PMID: 28504267 PMCID: PMC5440662 DOI: 10.1038/ncomms15348] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 03/22/2017] [Indexed: 12/05/2022] Open
Abstract
Electron energy-loss magnetic chiral dichroism is a powerful technique that allows the local magnetic properties of materials to be measured quantitatively with close-to-atomic spatial resolution and element specificity in the transmission electron microscope. Until now, the technique has been restricted to measurements of the magnetic circular dichroism signal in the electron beam direction. However, the intrinsic magnetization directions of thin samples are often oriented in the specimen plane, especially when they are examined in magnetic-field-free conditions in the transmission electron microscope. Here, we introduce an approach that allows in-plane magnetic signals to be measured using electron magnetic chiral dichroism by selecting a specific diffraction geometry. We compare experimental results recorded from a cobalt nanoplate with simulations to demonstrate that an electron magnetic chiral dichroism signal originating from in-plane magnetization can be detected successfully. Electron energy-loss magnetic chiral dichroism enables the measurement of the local magnetic properties of a material using a transmission electron microscope, but is limited to signals in the electron-beam direction. Here, the authors demonstrate a method to extend this to in-plane magnetic signals too.
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7
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Rusz J. Modified automatic term selection v2: A faster algorithm to calculate inelastic scattering cross-sections. Ultramicroscopy 2017; 177:20-25. [PMID: 28214388 DOI: 10.1016/j.ultramic.2017.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 01/08/2017] [Accepted: 01/21/2017] [Indexed: 11/17/2022]
Abstract
We present a new algorithm for calculating inelastic scattering cross-section for fast electrons. Compared to the previous Modified Automatic Term Selection (mats) algorithm (Rusz et al. [18]), it has far better convergence properties in zone axis calculations and it allows to identify contributions of individual atoms. One can think of it as a blend of mats algorithm and a method described by Weickenmeier and Kohl [10].
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Affiliation(s)
- Ján Rusz
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden.
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8
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Wang ZC, Zhong XY, Jin L, Chen XF, Moritomo Y, Mayer J. Effects of dynamic diffraction conditions on magnetic parameter determination in a double perovskite Sr 2FeMoO 6 using electron energy-loss magnetic chiral dichroism. Ultramicroscopy 2016; 176:212-217. [PMID: 28089306 DOI: 10.1016/j.ultramic.2016.12.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 12/23/2016] [Accepted: 12/29/2016] [Indexed: 10/20/2022]
Abstract
Electron energy-loss magnetic chiral dichroism (EMCD) spectroscopy, which is similar to the well-established X-ray magnetic circular dichroism spectroscopy (XMCD), can determine the quantitative magnetic parameters of materials with high spatial resolution. One of the major obstacles in quantitative analysis using the EMCD technique is the relatively poor signal-to-noise ratio (SNR), compared to XMCD. Here, in the example of a double perovskite Sr2FeMoO6, we predicted the optimal dynamical diffraction conditions such as sample thickness, crystallographic orientation and detection aperture position by theoretical simulations. By using the optimized conditions, we showed that the SNR of experimental EMCD spectra can be significantly improved and the error of quantitative magnetic parameter determined by EMCD technique can be remarkably lowered. Our results demonstrate that, with enhanced SNR, the EMCD technique can be a unique tool to understand the structure-property relationship of magnetic materials particularly in the high-density magnetic recording and spintronic devices by quantitatively determining magnetic structure and properties at the nanometer scale.
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Affiliation(s)
- Z C Wang
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - X Y Zhong
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
| | - L Jin
- Peter Grünberg Institute and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - X F Chen
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Y Moritomo
- Graduate School of Pure & Applied Science and Faculty of Pure & Applied Science, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-7571, Japan
| | - J Mayer
- Peter Grünberg Institute and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, 52425 Jülich, Germany; Central Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen, Germany
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9
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Schneider S, Pohl D, Löffler S, Rusz J, Kasinathan D, Schattschneider P, Schultz L, Rellinghaus B. Magnetic properties of single nanomagnets: Electron energy-loss magnetic chiral dichroism on FePt nanoparticles. Ultramicroscopy 2016; 171:186-194. [PMID: 27694036 DOI: 10.1016/j.ultramic.2016.09.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 09/05/2016] [Accepted: 09/18/2016] [Indexed: 11/24/2022]
Abstract
Electron energy-loss magnetic chiral dichroism (EMCD) allows for the quantification of magnetic properties of materials at the nanometer scale. It is shown that with the support of simulations that help to identify the optimal conditions for a successful experiment and upon implementing measurement routines that effectively reduce the noise floor, EMCD measurements can be pushed towards quantitative magnetic measurements even on individual nanoparticles. With this approach, the ratio of orbital to spin magnetic moments for the Fe atoms in a single L10 ordered FePt nanoparticle is determined to be ml/ms=0.08±0.02. This finding is in good quantitative agreement with the results of XMCD ensemble measurements.
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Affiliation(s)
- Sebastian Schneider
- IFW Dresden, Institute for Metallic Materials, PO Box 270116, D-01171 Dresden, Germany; TU Dresden, Institut für Festkörperphysik, D-01062 Dresden, Germany.
| | - Darius Pohl
- IFW Dresden, Institute for Metallic Materials, PO Box 270116, D-01171 Dresden, Germany
| | - Stefan Löffler
- TU Wien, University Service Centre for Electron Microscopy, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria; McMaster University, Department of Materials Science and Engineering, 1280 Main Street West, Hamilton, Ontario, Canada L8S4L8
| | - Ján Rusz
- Uppsala University, Department of Physics and Astronomy, PO Box 516, S-75120 Uppsala, Sweden
| | - Deepa Kasinathan
- Max-Planck-Institut für Chemische Physik fester Stoffe, Department of Physics of Correlated Matter, Nöthnitzer Straße 40, D-01187 Dresden, Germany
| | - Peter Schattschneider
- TU Wien, University Service Centre for Electron Microscopy, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria; TU Wien, Institute of Solid State Physics, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria
| | - Ludwig Schultz
- IFW Dresden, Institute for Metallic Materials, PO Box 270116, D-01171 Dresden, Germany; TU Dresden, Institut für Festkörperphysik, D-01062 Dresden, Germany
| | - Bernd Rellinghaus
- IFW Dresden, Institute for Metallic Materials, PO Box 270116, D-01171 Dresden, Germany
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10
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Song D, Rusz J, Cai J, Zhu J. Detection of electron magnetic circular dichroism signals under zone axial diffraction geometry. Ultramicroscopy 2016; 169:44-54. [DOI: 10.1016/j.ultramic.2016.07.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 06/28/2016] [Accepted: 07/03/2016] [Indexed: 11/26/2022]
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11
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Song D, Li G, Cai J, Zhu J. A general way for quantitative magnetic measurement by transmitted electrons. Sci Rep 2016; 6:18489. [PMID: 26726959 PMCID: PMC4698752 DOI: 10.1038/srep18489] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 11/18/2015] [Indexed: 11/09/2022] Open
Abstract
EMCD (electron magnetic circular dichroism) technique opens a new door to explore magnetic properties by transmitted electrons. The recently developed site-specific EMCD technique makes it possible to obtain rich magnetic information from the Fe atoms sited at nonequivalent crystallographic planes in NiFe2O4, however it is based on a critical demand for the crystallographic structure of the testing sample. Here, we have further improved and tested the method for quantitative site-specific magnetic measurement applicable for more complex crystallographic structure by using the effective dynamical diffraction effects (general routine for selecting proper diffraction conditions, making use of the asymmetry of dynamical diffraction for design of experimental geometry and quantitative measurement, etc), and taken yttrium iron garnet (Y3Fe5O12, YIG) with more complex crystallographic structure as an example to demonstrate its applicability. As a result, the intrinsic magnetic circular dichroism signals, spin and orbital magnetic moment of iron with site-specific are quantitatively determined. The method will further promote the development of quantitative magnetic measurement with high spatial resolution by transmitted electrons.
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Affiliation(s)
- Dongsheng Song
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE) and The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Gen Li
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE) and The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Jianwang Cai
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jing Zhu
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE) and The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
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12
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Kudo T, Tatsumi K, Muto S, Leifer K, Rusz J. B11-P-01Magnetocrystalline anisotropy of hexagonal Co by relative intensities of electron magnetic circular dichroic signals. Microscopy (Oxf) 2015. [DOI: 10.1093/jmicro/dfv205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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13
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Thersleff T, Rusz J, Rubino S, Hjörvarsson B, Ito Y, J. Zaluzec N, Leifer K. Quantitative analysis of magnetic spin and orbital moments from an oxidized iron (1 1 0) surface using electron magnetic circular dichroism. Sci Rep 2015; 5:13012. [PMID: 26278134 PMCID: PMC4538391 DOI: 10.1038/srep13012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 07/03/2015] [Indexed: 11/17/2022] Open
Abstract
Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.
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Affiliation(s)
- Thomas Thersleff
- Department of Engineering Sciences, Division of Applied Materials, Uppsala University, Uppsala, Sweden
| | - Jan Rusz
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Stefano Rubino
- Department of Engineering Sciences, Division of Applied Materials, Uppsala University, Uppsala, Sweden
- Department of Physics, University of Oslo, Oslo, Norway
| | | | - Yasuo Ito
- Department of Physics, Northern Illinois University, DeKalb, IL, USA
| | - Nestor J. Zaluzec
- Electron Microscopy Center, NanoScience and Technology Division, Argonne National Laboratory, Argonne, IL, USA
| | - Klaus Leifer
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
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14
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Hetaba W, Löffler S, Willinger MG, Schuster ME, Schlögl R, Schattschneider P. Site-specific ionisation edge fine-structure of Rutile in the electron microscope. Micron 2014; 63:15-9. [PMID: 24629520 DOI: 10.1016/j.micron.2014.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 02/12/2014] [Accepted: 02/12/2014] [Indexed: 10/25/2022]
Abstract
Combined Bloch-wave and density functional theory simulations are performed to investigate the effects of different channelling conditions on the fine-structure of electron energy-loss spectra. The simulated spectra compare well with experiments. Furthermore, we demonstrate that using this technique, the site-specific investigation of atomic orbitals is possible. This opens new possibilities for chemical analyses.
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Affiliation(s)
- Walid Hetaba
- University Service Centre for Transmission Electron Microscopy, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Wien, Austria; Thin Films and Physics of Nanostructures, Department of Physics, Bielefeld University, Universitätsstrasse 25, D-33615 Bielefeld, Germany.
| | - Stefan Löffler
- University Service Centre for Transmission Electron Microscopy, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Wien, Austria
| | - Marc-Georg Willinger
- Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Manfred Erwin Schuster
- Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Robert Schlögl
- Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Peter Schattschneider
- University Service Centre for Transmission Electron Microscopy, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Wien, Austria; Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Wien, Austria
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15
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Tatsumi K, Muto S, Rusz J, Kudo T, Arai S. Signal enhancement of electron magnetic circular dichroism by ultra-high-voltage TEM, toward quantitative nano-magnetism measurements. Microscopy (Oxf) 2014; 63:243-7. [DOI: 10.1093/jmicro/dfu002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Kazuyoshi Tatsumi
- EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Shunsuke Muto
- EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-75120, Sweden
| | - Tomohiro Kudo
- Graduate school of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Shigeo Arai
- EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
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Quantitative characterization of nanoscale polycrystalline magnets with electron magnetic circular dichroism. Nat Commun 2014; 5:3138. [DOI: 10.1038/ncomms4138] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Accepted: 12/17/2013] [Indexed: 11/08/2022] Open
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Tatsumi K, Muto S, Rusz J. Energy loss by channeled electrons: a quantitative study on transition metal oxides. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2013; 19:1586-1594. [PMID: 23985156 DOI: 10.1017/s1431927613013214] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Electron energy-loss spectroscopy (EELS) attached to current transmission electron microscopes can probe not only element-selective chemical information, but also site-selective information that depends on the position that a specific element occupies in a crystal lattice. The latter information is exploited by utilizing the Bloch waves symmetry in the crystal, which changes with its orientation with respect to the incident electron wave (electron channeling). We demonstrate the orientation dependence of the cross-section of the electron energy-loss near-edge structure for particular crystalline sites of spinel ferrites, by quantitatively taking into account the dynamical diffraction effects with a large number of the diffracted beams. The theoretical results are consistent with a set of experiments in which the transition metal sites in spinel crystal structures are selectively excited. A new measurement scheme for site-selective EELS using a two-dimensional position-sensitive detector is proposed and validated by theoretical predictions and trial experiments.
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Affiliation(s)
- Kazuyoshi Tatsumi
- Department of Materials, Physics and Energy Engineering, Nagoya University, Chikusa, Nagoya, Aichi Pref. 464-8603, Japan
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Rusz J, Bhowmick S. Boundaries for efficient use of electron vortex beams to measure magnetic properties. PHYSICAL REVIEW LETTERS 2013; 111:105504. [PMID: 25166681 DOI: 10.1103/physrevlett.111.105504] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2013] [Indexed: 05/14/2023]
Abstract
Development of experimental techniques for characterization of magnetic properties at high spatial resolution is essential for progress in miniaturization of magnetic devices, for example, in data storage media. Inelastic scattering of electron vortex beams (EVBs) was recently reported to contain atom-specific magnetic information. We develop a theoretical description of inelastic scattering of EVBs on crystals and perform simulations for EVBs of different diameters. We show that use of an EVB wider than an interatomic distance does not provide any advantage over an ordinary convergent beam without angular momentum. On the other hand, in the atomic-resolution limit, electron energy loss spectra measured by EVBs are strongly sensitive to the spin and orbital magnetic moments of studied matter, when channeling through or very close to the atomic columns. Our results demonstrate the boundaries for efficient use of EVBs in measurement of magnetic properties.
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Affiliation(s)
- Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Post Office Box 516, 75120 Uppsala, Sweden and Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Prague, Czech Republic
| | - Somnath Bhowmick
- Department of Physics and Astronomy, Uppsala University, Post Office Box 516, 75120 Uppsala, Sweden and Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208016, India
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Muto S, Tatsumi K, Rusz J. Parameter-free extraction of EMCD from an energy-filtered diffraction datacube using multivariate curve resolution. Ultramicroscopy 2013; 125:89-96. [DOI: 10.1016/j.ultramic.2012.09.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 09/15/2012] [Accepted: 09/23/2012] [Indexed: 11/30/2022]
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