1
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Nicholls D, Kobylynska M, Broad Z, Wells J, Robinson A, McGrouther D, Moshtaghpour A, Kirkland AI, Fleck RA, Browning ND. The Potential of Subsampling and Inpainting for Fast Low-Dose Cryo FIB-SEM Imaging. Microsc Microanal 2024; 30:96-102. [PMID: 38321738 DOI: 10.1093/micmic/ozae005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 12/13/2023] [Accepted: 01/06/2024] [Indexed: 02/08/2024]
Abstract
Traditional image acquisition for cryo focused ion-beam scanning electron microscopy (FIB-SEM) tomography often sees thousands of images being captured over a period of many hours, with immense data sets being produced. When imaging beam sensitive materials, these images are often compromised by additional constraints related to beam damage and the devitrification of the material during imaging, which renders data acquisition both costly and unreliable. Subsampling and inpainting are proposed as solutions for both of these aspects, allowing fast and low-dose imaging to take place in the Focused ion-beam scanning electron microscopy FIB-SEM without an appreciable loss in image quality. In this work, experimental data are presented which validate subsampling and inpainting as a useful tool for convenient and reliable data acquisition in a FIB-SEM, with new methods of handling three-dimensional data being employed in the context of dictionary learning and inpainting algorithms using a newly developed microscope control software and data recovery algorithm.
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Affiliation(s)
- Daniel Nicholls
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, L69 3BX, UK
- SenseAI Innovations Ltd., Liverpool, L69 3BX, UK
| | - Maryna Kobylynska
- Centre for Ultrastructural Imaging, King's College London, London, WC2R 2LS, UK
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, WC2R 2LS, UK
| | - Zoë Broad
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, L69 3BX, UK
| | - Jack Wells
- Distributed Algorithms Centre for Doctoral Training, University of Liverpool, Liverpool, L69 3BX, UK
| | - Alex Robinson
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, L69 3BX, UK
- SenseAI Innovations Ltd., Liverpool, L69 3BX, UK
| | | | - Amirafshar Moshtaghpour
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, L69 3BX, UK
- Correlated Imaging Group, Rosalind Franklin Institute, Didcot, OX11 0QS, UK
| | - Angus I Kirkland
- Correlated Imaging Group, Rosalind Franklin Institute, Didcot, OX11 0QS, UK
- Department of Materials, University of Oxford, Oxford, OX2 6NN, UK
| | - Roland A Fleck
- Centre for Ultrastructural Imaging, King's College London, London, WC2R 2LS, UK
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, WC2R 2LS, UK
| | - Nigel D Browning
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, L69 3BX, UK
- SenseAI Innovations Ltd., Liverpool, L69 3BX, UK
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2
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Cascales-Sandoval MA, Hierro-Rodriguez A, Ruiz-Gómez S, Skoric L, Donnelly C, Niño MA, McGrouther D, McVitie S, Flewett S, Jaouen N, Belkhou R, Foerster M, Fernandez-Pacheco A. Determination of optimal experimental conditions for accurate 3D reconstruction of the magnetization vector via XMCD-PEEM. J Synchrotron Radiat 2024; 31:336-342. [PMID: 38372673 PMCID: PMC10914169 DOI: 10.1107/s1600577524001073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/31/2024] [Indexed: 02/20/2024]
Abstract
This work presents a detailed analysis of the performance of X-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) as a tool for vector reconstruction of magnetization. For this, 360° domain wall ring structures which form in a synthetic antiferromagnet are chosen as the model to conduct the quantitative analysis. An assessment is made of how the quality of the results is affected depending on the number of projections that are involved in the reconstruction process, as well as their angular distribution. For this a self-consistent error metric is developed which allows an estimation of the optimum azimuthal rotation angular range and number of projections. This work thus proposes XMCD-PEEM as a powerful tool for vector imaging of complex 3D magnetic structures.
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Affiliation(s)
- Miguel A. Cascales-Sandoval
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
- Institute of Applied Physics, TU Wien, Wiedner Hauptstraße 8–10, 1040 Vienna, Austria
| | - A. Hierro-Rodriguez
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
- Departamento de Física, Universidad de Oviedo, 33007 Oviedo, Spain
- CINN, CSIC-Universidad de Oviedo, 33940 El Entrego, Spain
| | - S. Ruiz-Gómez
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - L. Skoric
- University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - C. Donnelly
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - M. A. Niño
- ALBA Synchrotron Light Facility, 08290 Cerdanyola del Vallés, Spain
| | - D. McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - S. McVitie
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - S. Flewett
- Instituto de Física, Pontificia Universidad Católica de Valparaíso, Avenida Universidad 330, Valparaíso, Chile
| | - N. Jaouen
- Synchrotron SOLEIL, L’Orme des Merisiers, 91192 Gif-Sur-Yvette Cedex, France
| | - R. Belkhou
- Synchrotron SOLEIL, L’Orme des Merisiers, 91192 Gif-Sur-Yvette Cedex, France
| | - M. Foerster
- ALBA Synchrotron Light Facility, 08290 Cerdanyola del Vallés, Spain
| | - A. Fernandez-Pacheco
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
- Institute of Applied Physics, TU Wien, Wiedner Hauptstraße 8–10, 1040 Vienna, Austria
- Instituto de Nanociencia y Materiales de Aragón, CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain
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3
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Nord M, Barthel J, Allen CS, McGrouther D, Kirkland AI, MacLaren I. Atomic resolution HOLZ-STEM imaging of atom position modulation in oxide heterostructures. Ultramicroscopy 2021; 226:113296. [PMID: 34004555 DOI: 10.1016/j.ultramic.2021.113296] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 03/16/2021] [Accepted: 04/24/2021] [Indexed: 11/26/2022]
Abstract
It is shown that higher order Laue zone (HOLZ) rings in high energy electron diffraction are specific to individual columns of atoms, and show different strengths, structure and radii for different atom columns along the same projection in a structure. An atomic resolution 4-dimensional STEM dataset is recorded from a <110> direction in a perovskite trilayer, where only the central LaFeO3 layer should show a period doubling that gives rise to an extra HOLZ ring. Careful comparison between experiment and multislice simulations is used to understand the origins of all features in the patterns. A strong HOLZ ring is seen for the La-O columns, indicating strong La position modulation along this direction, whereas a weaker ring is seen along the O columns, and a very weak ring is seen along the Fe columns. This demonstrates that atomic resolution HOLZ-STEM is a feasible method for investigating the 3D periodicity of crystalline materials with atomic resolution.
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Affiliation(s)
- Magnus Nord
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK; Department of Physics, NTNU, Høgskoleringen 5, 7491, Trondheim, Norway
| | - Juri Barthel
- Ernst Ruska-Centre (ER-C 2), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Christopher S Allen
- electron Physical Science Imaging Centre, Diamond Light Source Ltd., OX11 0DE, UK; Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Damien McGrouther
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - Angus I Kirkland
- electron Physical Science Imaging Centre, Diamond Light Source Ltd., OX11 0DE, UK; Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Ian MacLaren
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK.
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4
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Paton KA, Veale MC, Mu X, Allen CS, Maneuski D, Kübel C, O'Shea V, Kirkland AI, McGrouther D. Quantifying the performance of a hybrid pixel detector with GaAs:Cr sensor for transmission electron microscopy. Ultramicroscopy 2021; 227:113298. [PMID: 34051540 DOI: 10.1016/j.ultramic.2021.113298] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 02/01/2021] [Accepted: 04/24/2021] [Indexed: 10/21/2022]
Abstract
Hybrid pixel detectors (HPDs) have been shown to be highly effective for diffraction-based and time-resolved studies in transmission electron microscopy, but their performance is limited by the fact that high-energy electrons scatter over long distances in their thick Si sensors. An advantage of HPDs compared to monolithic active pixel sensors is that their sensors do not need to be fabricated from Si. We have compared the performance of the Medipix3 HPD with a Si sensor and a GaAs:Cr sensor using primary electrons in the energy range of 60-300 keV. We describe the measurement and calculation of the detectors' modulation transfer function (MTF) and detective quantum efficiency (DQE), which show that the performance of the GaAs:Cr device is markedly superior to that of the Si device for high-energy electrons.
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Affiliation(s)
- Kirsty A Paton
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, G12 8QQ, UK.
| | - Matthew C Veale
- UKRI Science & Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Xiaoke Mu
- Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Christopher S Allen
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK; electron Physical Sciences Imaging Centre (ePSIC), Diamond Lightsource Ltd., Didcot, OX11 0DE, UK
| | - Dzmitry Maneuski
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, G12 8QQ, UK
| | - Christian Kübel
- Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany; Department of Materials and Earth Science, Technische Universität Darmstadt and Karlsruhe Institute of Technology, Otto-Berndt-Str. 3, 64287 Darmstadt, Germany
| | - Val O'Shea
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, G12 8QQ, UK
| | - Angus I Kirkland
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK; electron Physical Sciences Imaging Centre (ePSIC), Diamond Lightsource Ltd., Didcot, OX11 0DE, UK
| | - Damien McGrouther
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, G12 8QQ, UK
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5
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MacLaren I, Frutos-Myro E, McGrouther D, McFadzean S, Weiss JK, Cosart D, Portillo J, Robins A, Nicolopoulos S, Nebot Del Busto E, Skogeby R. A Comparison of a Direct Electron Detector and a High-Speed Video Camera for a Scanning Precession Electron Diffraction Phase and Orientation Mapping. Microsc Microanal 2020; 26:1110-1116. [PMID: 32867871 DOI: 10.1017/s1431927620024411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A scanning precession electron diffraction system has been integrated with a direct electron detector to allow the collection of improved quality diffraction patterns. This has been used on a two-phase α–β titanium alloy (Timetal® 575) for phase and orientation mapping using an existing pattern-matching algorithm and has been compared to the commonly used detector system, which consisted of a high-speed video-camera imaging the small phosphor focusing screen. Noise is appreciably lower with the direct electron detector, and this is especially noticeable further from the diffraction pattern center where the real electron scattering is reduced and both diffraction spots and inelastic scattering between spots are weaker. The results for orientation mapping are a significant improvement in phase and orientation indexing reliability, especially of fine nanoscale laths of α-Ti, where the weak diffracted signal is rather lost in the noise for the optically coupled camera. This was done at a dose of ~19 e−/Å2, and there is clearly a prospect for reducing the current further while still producing indexable patterns. This opens the way for precession diffraction phase and orientation mapping of radiation-sensitive crystalline materials.
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Affiliation(s)
- Ian MacLaren
- School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | | | - Damien McGrouther
- School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Sam McFadzean
- School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Jon Karl Weiss
- NanoMEGAS USA, 1095 W Rio Salado Parkway, Suite 110, Tempe, AZ85281, USA
| | - Doug Cosart
- NanoMEGAS USA, 1095 W Rio Salado Parkway, Suite 110, Tempe, AZ85281, USA
| | - Joaquim Portillo
- NanoMEGAS SPRL, Bd.Edmond Machtens 79 bte 22, 1080Brussels, Belgium
- Centres Cientifics i Tecnologics, Universitat de Barcelona, Sole i Sabaris, 1-3, Barcelona08028, Spain
| | - Alan Robins
- NanoMEGAS SPRL, Bd.Edmond Machtens 79 bte 22, 1080Brussels, Belgium
| | | | | | - Richard Skogeby
- Quantum Detectors Ltd., R104, RAL, Harwell, OxfordOX11 0QX, UK
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6
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Paterson GW, Webster RWH, Ross A, Paton KA, Macgregor TA, McGrouther D, MacLaren I, Nord M. Fast Pixelated Detectors in Scanning Transmission Electron Microscopy. Part II: Post-Acquisition Data Processing, Visualization, and Structural Characterization. Microsc Microanal 2020; 26:944-963. [PMID: 32883393 DOI: 10.1017/s1431927620024307] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Fast pixelated detectors incorporating direct electron detection (DED) technology are increasingly being regarded as universal detectors for scanning transmission electron microscopy (STEM), capable of imaging under multiple modes of operation. However, several issues remain around the post-acquisition processing and visualization of the often very large multidimensional STEM datasets produced by them. We discuss these issues and present open source software libraries to enable efficient processing and visualization of such datasets. Throughout, we provide examples of the analysis methodologies presented, utilizing data from a 256 × 256 pixel Medipix3 hybrid DED detector, with a particular focus on the STEM characterization of the structural properties of materials. These include the techniques of virtual detector imaging; higher-order Laue zone analysis; nanobeam electron diffraction; and scanning precession electron diffraction. In the latter, we demonstrate a nanoscale lattice parameter mapping with a fractional precision ≤6 × 10−4 (0.06%).
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Affiliation(s)
- Gary W Paterson
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Robert W H Webster
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Andrew Ross
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Kirsty A Paton
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Thomas A Macgregor
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Ian MacLaren
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Magnus Nord
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
- EMAT, Department of Physics, University of Antwerp, Antwerp2000, Belgium
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7
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Nord M, Webster RWH, Paton KA, McVitie S, McGrouther D, MacLaren I, Paterson GW. Fast Pixelated Detectors in Scanning Transmission Electron Microscopy. Part I: Data Acquisition, Live Processing, and Storage. Microsc Microanal 2020; 26:653-666. [PMID: 32627727 DOI: 10.1017/s1431927620001713] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The use of fast pixelated detectors and direct electron detection technology is revolutionizing many aspects of scanning transmission electron microscopy (STEM). The widespread adoption of these new technologies is impeded by the technical challenges associated with them. These include issues related to hardware control, and the acquisition, real-time processing and visualization, and storage of data from such detectors. We discuss these problems and present software solutions for them, with a view to making the benefits of new detectors in the context of STEM more accessible. Throughout, we provide examples of the application of the technologies presented, using data from a Medipix3 direct electron detector. Most of our software are available under an open source licence, permitting transparency of the implemented algorithms, and allowing the community to freely use and further improve upon them.
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Affiliation(s)
- Magnus Nord
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
- EMAT, Department of Physics, University of Antwerp, Antwerp2000, Belgium
| | - Robert W H Webster
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Kirsty A Paton
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Stephen McVitie
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Ian MacLaren
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
| | - Gary W Paterson
- SUPA, School of Physics and Astronomy, University of Glasgow, GlasgowG12 8QQ, UK
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8
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Rendell-Bhatti F, Lamb RJ, van der Jagt JW, Paterson GW, Swagten HJM, McGrouther D. Spontaneous creation and annihilation dynamics and strain-limited stability of magnetic skyrmions. Nat Commun 2020; 11:3536. [PMID: 32669654 PMCID: PMC7363836 DOI: 10.1038/s41467-020-17338-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 06/24/2020] [Indexed: 11/08/2022] Open
Abstract
Magnetic skyrmions are topological magnetic spin structures exhibiting particle-like behaviour. They are of strong interest from a fundamental viewpoint and for application, where they have potential to act as information carriers in future low-power computing technologies. Importantly, skyrmions have high physical stability because of topological protection. However, they have potential to deform according to their local energy environment. Here we demonstrate that, in regions of high exchange energy density, skyrmions may exhibit such extreme deformation that spontaneous merging with nearest neighbours or spawning new skyrmions is favoured to attain a lower energy state. Using transmission electron microscopy and a high-speed imaging detector, we observe dynamics involving distinct configurational states, in which transitions are accompanied by spontaneous creation or annihilation of skyrmions. These observations raise important questions regarding the limits of skyrmion stability and topological charge conservation, while also suggesting a means of control of skyrmion creation and annihilation.
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Affiliation(s)
| | - Raymond J Lamb
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Johannes W van der Jagt
- Department of Applied Physics, Eindhoven University of Technology, 5612 AZ, Eindhoven, The Netherlands
| | - Gary W Paterson
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Henk J M Swagten
- Department of Applied Physics, Eindhoven University of Technology, 5612 AZ, Eindhoven, The Netherlands
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
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9
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Fallon K, Hughes S, Zeissler K, Legrand W, Ajejas F, Maccariello D, McFadzean S, Smith W, McGrouther D, Collin S, Reyren N, Cros V, Marrows CH, McVitie S. Controlled Individual Skyrmion Nucleation at Artificial Defects Formed by Ion Irradiation. Small 2020; 16:e1907450. [PMID: 32141234 DOI: 10.1002/smll.201907450] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 06/10/2023]
Abstract
Magnetic skyrmions are particle-like deformations in a magnetic texture. They have great potential as information carriers in spintronic devices because of their interesting topological properties and favorable motion under spin currents. A new method of nucleating skyrmions at nanoscale defect sites, created in a controlled manner with focused ion beam irradiation, in polycrystalline magnetic multilayer samples with an interfacial Dzyaloshinskii-Moriya interaction, is reported. This new method has three notable advantages: 1) localization of nucleation; 2) stability over a larger range of external field strengths, including stability at zero field; and 3) existence of skyrmions in material systems where, prior to defect fabrication, skyrmions were not previously obtained by field cycling. Additionally, it is observed that the size of defect nucleated skyrmions is uninfluenced by the defect itself-provided that the artificial defects are controlled to be smaller than the inherent skyrmion size. All of these characteristics are expected to be useful toward the goal of realizing a skyrmion-based spintronic device. This phenomenon is studied with a range of transmission electron microscopy techniques to probe quantitatively the magnetic behavior at the defects with applied field and correlate this with the structural impact of the defects.
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Affiliation(s)
- Kayla Fallon
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Sean Hughes
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Katharina Zeissler
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, Palaiseau, 91767, France
| | - William Legrand
- National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK
| | - Fernando Ajejas
- National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK
| | | | - Samuel McFadzean
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - William Smith
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Damien McGrouther
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Sophie Collin
- National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK
| | - Nicolas Reyren
- National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK
| | - Vincent Cros
- National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK
| | | | - Stephen McVitie
- SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
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10
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Paterson GW, Lamb RJ, Ballabriga R, Maneuski D, O'Shea V, McGrouther D. Sub-100 nanosecond temporally resolved imaging with the Medipix3 direct electron detector. Ultramicroscopy 2019; 210:112917. [PMID: 31841837 DOI: 10.1016/j.ultramic.2019.112917] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/13/2019] [Accepted: 12/03/2019] [Indexed: 11/17/2022]
Abstract
Detector developments are currently enabling new capabilities in the field of transmission electron microscopy (TEM). We have investigated the limits of a hybrid pixel detector, Medipix3, to record dynamic, time varying, electron signals. Operating with an energy of 60 keV, we have utilised electrostatic deflection to oscillate electron beam position on the detector. Adopting a pump-probe imaging strategy, we have demonstrated that temporal resolutions three orders of magnitude smaller than are available for typically used TEM imaging detectors are possible. Our experiments have shown that energy deposition of the primary electrons in the hybrid pixel detector limits the overall temporal resolution. Through adjustment of user specifiable thresholds or the use of charge summing mode, we have obtained images composed from summing 10,000s frames containing single electron events to achieve temporal resolution less than 100 ns. We propose that this capability can be directly applied to studying repeatable material dynamic processes but also to implement low-dose imaging schemes in scanning transmission electron microscopy.
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Affiliation(s)
- Gary W Paterson
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
| | - Raymond J Lamb
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
| | | | - Dima Maneuski
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Val O'Shea
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
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11
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Vanacore GM, Madan I, Berruto G, Wang K, Pomarico E, Lamb RJ, McGrouther D, Kaminer I, Barwick B, de Abajo FJG, Carbone F. Author Correction: Attosecond coherent control of free-electron wave functions using semi-infinite light fields. Nat Commun 2019; 10:1069. [PMID: 30824703 PMCID: PMC6397259 DOI: 10.1038/s41467-019-08996-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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12
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Nord M, Semisalova A, Kákay A, Hlawacek G, MacLaren I, Liersch V, Volkov OM, Makarov D, Paterson GW, Potzger K, Lindner J, Fassbender J, McGrouther D, Bali R. Strain Anisotropy and Magnetic Domains in Embedded Nanomagnets. Small 2019; 15:e1904738. [PMID: 31709733 DOI: 10.1002/smll.201904738] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/27/2019] [Indexed: 06/10/2023]
Abstract
Nanoscale modifications of strain and magnetic anisotropy can open pathways to engineering magnetic domains for device applications. A periodic magnetic domain structure can be stabilized in sub-200 nm wide linear as well as curved magnets, embedded within a flat non-ferromagnetic thin film. The nanomagnets are produced within a non-ferromagnetic B2-ordered Fe60 Al40 thin film, where local irradiation by a focused ion beam causes the formation of disordered and strongly ferromagnetic regions of A2 Fe60 Al40 . An anisotropic lattice relaxation is observed, such that the in-plane lattice parameter is larger when measured parallel to the magnet short-axis as compared to its length. This in-plane structural anisotropy manifests a magnetic anisotropy contribution, generating an easy-axis parallel to the short axis. The competing effect of the strain and shape anisotropies stabilizes a periodic domain pattern in linear as well as spiral nanomagnets, providing a versatile and geometrically controllable path to engineering the strain and thereby the magnetic anisotropy at the nanoscale.
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Affiliation(s)
- Magnus Nord
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
- Electron Microscopy for Materials Science, University of Antwerp, Antwerp, 2000, Belgium
| | - Anna Semisalova
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
| | - Attila Kákay
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
| | - Gregor Hlawacek
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
| | - Ian MacLaren
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Vico Liersch
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
| | - Oleksii M Volkov
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
| | - Denys Makarov
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
| | - Gary W Paterson
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Kay Potzger
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
| | - Jürgen Lindner
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
| | - Jürgen Fassbender
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Rantej Bali
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
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13
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Vanacore GM, Berruto G, Madan I, Pomarico E, Biagioni P, Lamb RJ, McGrouther D, Reinhardt O, Kaminer I, Barwick B, Larocque H, Grillo V, Karimi E, García de Abajo FJ, Carbone F. Ultrafast generation and control of an electron vortex beam via chiral plasmonic near fields. Nat Mater 2019; 18:573-579. [PMID: 31061485 DOI: 10.1038/s41563-019-0336-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 03/07/2019] [Indexed: 05/27/2023]
Abstract
Vortex-carrying matter waves, such as chiral electron beams, are of significant interest in both applied and fundamental science. Continuous-wave electron vortex beams are commonly prepared via passive phase masks imprinting a transverse phase modulation on the electron's wavefunction. Here, we show that femtosecond chiral plasmonic near fields enable the generation and dynamic control on the ultrafast timescale of an electron vortex beam. The vortex structure of the resulting electron wavepacket is probed in both real and reciprocal space using ultrafast transmission electron microscopy. This method offers a high degree of scalability to small length scales and a highly efficient manipulation of the electron vorticity with attosecond precision. Besides the direct implications in the investigation of nanoscale ultrafast processes in which chirality plays a major role, we further discuss the perspectives of using this technique to shape the wavefunction of charged composite particles, such as protons, and how it can be used to probe their internal structure.
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Affiliation(s)
- G M Vanacore
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
| | - G Berruto
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - I Madan
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - E Pomarico
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - P Biagioni
- Dipartimento di Fisica, Politecnico di Milano, Milano, Italy
| | - R J Lamb
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, UK
| | - D McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, UK
| | - O Reinhardt
- Faculty of Electrical Engineering and Solid State Institute, Technion, Haifa, Israel
| | - I Kaminer
- Faculty of Electrical Engineering and Solid State Institute, Technion, Haifa, Israel
| | | | - H Larocque
- Department of Physics, University of Ottawa, Ottawa, Ontario, Canada
| | - V Grillo
- CNR-Istituto Nanoscienze, Centro S3, Modena, Italy
| | - E Karimi
- Department of Physics, University of Ottawa, Ottawa, Ontario, Canada
| | - F J García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
| | - F Carbone
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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14
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Madan I, Vanacore GM, Pomarico E, Berruto G, Lamb RJ, McGrouther D, Lummen TTA, Latychevskaia T, García de Abajo FJ, Carbone F. Holographic imaging of electromagnetic fields via electron-light quantum interference. Sci Adv 2019; 5:eaav8358. [PMID: 31058225 PMCID: PMC6499551 DOI: 10.1126/sciadv.aav8358] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 03/15/2019] [Indexed: 05/22/2023]
Abstract
Holography relies on the interference between a known reference and a signal of interest to reconstruct both the amplitude and the phase of that signal. With electrons, the extension of holography to the ultrafast time domain remains a challenge, although it would yield the highest possible combined spatiotemporal resolution. Here, we show that holograms of local electromagnetic fields can be obtained with combined attosecond/nanometer resolution in an ultrafast transmission electron microscope (UEM). Unlike conventional holography, where signal and reference are spatially separated and then recombined to interfere, our method relies on electromagnetic fields to split an electron wave function in a quantum coherent superposition of different energy states. In the image plane, spatial modulation of the electron energy distribution reflects the phase relation between reference and signal fields. Beyond imaging applications, this approach allows implementing quantum measurements in parallel, providing an efficient and versatile tool for electron quantum optics.
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Affiliation(s)
- I. Madan
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - G. M. Vanacore
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - E. Pomarico
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - G. Berruto
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - R. J. Lamb
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - D. McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - T. T. A. Lummen
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - T. Latychevskaia
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - F. J. García de Abajo
- ICFO–Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- ICREA–Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - F. Carbone
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
- Corresponding author.
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15
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McVitie S, Hughes S, Fallon K, McFadzean S, McGrouther D, Krajnak M, Legrand W, Maccariello D, Collin S, Garcia K, Reyren N, Cros V, Fert A, Zeissler K, Marrows CH. A transmission electron microscope study of Néel skyrmion magnetic textures in multilayer thin film systems with large interfacial chiral interaction. Sci Rep 2018; 8:5703. [PMID: 29632330 PMCID: PMC5890272 DOI: 10.1038/s41598-018-23799-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 03/21/2018] [Indexed: 12/05/2022] Open
Abstract
Skyrmions in ultrathin ferromagnetic metal (FM)/heavy metal (HM) multilayer systems produced by conventional sputtering methods have recently generated huge interest due to their applications in the field of spintronics. The sandwich structure with two correctly-chosen heavy metal layers provides an additive interfacial exchange interaction which promotes domain wall or skyrmion spin textures that are Néel in character and with a fixed chirality. Lorentz transmission electron microscopy (TEM) is a high resolution method ideally suited to quantitatively image such chiral magnetic configurations. When allied with physical and chemical TEM analysis of both planar and cross-sectional samples, key length scales such as grain size and the chiral variation of the magnetisation variation have been identified and measured. We present data showing the importance of the grain size (mostly < 10 nm) measured from direct imaging and its potential role in describing observed behaviour of isolated skyrmions (diameter < 100 nm). In the latter the region in which the magnetization rotates is measured to be around 30 nm. Such quantitative information on the multiscale magnetisation variations in the system is key to understanding and exploiting the behaviour of skyrmions for future applications in information storage and logic devices.
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Affiliation(s)
- S McVitie
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.
| | - S Hughes
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - K Fallon
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - S McFadzean
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - D McGrouther
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - M Krajnak
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.,Department of Materials Science and Engineering, Monash University, Clayton, Victoria, 3800, Australia
| | - W Legrand
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - D Maccariello
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - S Collin
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - K Garcia
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - N Reyren
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - V Cros
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - A Fert
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - K Zeissler
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - C H Marrows
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom
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16
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Berruto G, Madan I, Murooka Y, Vanacore GM, Pomarico E, Rajeswari J, Lamb R, Huang P, Kruchkov AJ, Togawa Y, LaGrange T, McGrouther D, Rønnow HM, Carbone F. Laser-Induced Skyrmion Writing and Erasing in an Ultrafast Cryo-Lorentz Transmission Electron Microscope. Phys Rev Lett 2018; 120:117201. [PMID: 29601740 DOI: 10.1103/physrevlett.120.117201] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Indexed: 05/27/2023]
Abstract
We demonstrate that light-induced heat pulses of different duration and energy can write Skyrmions in a broad range of temperatures and magnetic field in FeGe. Using a combination of camera-rate and pump-probe cryo-Lorentz transmission electron microscopy, we directly resolve the spatiotemporal evolution of the magnetization ensuing optical excitation. The Skyrmion lattice was found to maintain its structural properties during the laser-induced demagnetization, and its recovery to the initial state happened in the sub-μs to μs range, depending on the cooling rate of the system.
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Affiliation(s)
- G Berruto
- Institute of Physics, LUMES, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - I Madan
- Institute of Physics, LUMES, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Y Murooka
- Institute of Physics, LUMES, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - G M Vanacore
- Institute of Physics, LUMES, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - E Pomarico
- Institute of Physics, LUMES, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - J Rajeswari
- Institute of Physics, LUMES, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - R Lamb
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - P Huang
- Institute of Physics, LUMES, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
- Institute of Physics, LQM, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - A J Kruchkov
- Institute of Physics, LQM, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Y Togawa
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
- Osaka Prefecture University, 1-2 Gakuencho, Sakai, Osaka 599-8570, Japan
- Chirality Research Center (CResCent), Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - T LaGrange
- Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - D McGrouther
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - H M Rønnow
- Institute of Physics, LQM, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - F Carbone
- Institute of Physics, LUMES, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
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17
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Almeida TP, Temple R, Massey J, Fallon K, McGrouther D, Moore T, Marrows CH, McVitie S. Quantitative TEM imaging of the magnetostructural and phase transitions in FeRh thin film systems. Sci Rep 2017; 7:17835. [PMID: 29259255 PMCID: PMC5736605 DOI: 10.1038/s41598-017-18194-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 12/07/2017] [Indexed: 11/26/2022] Open
Abstract
Equi-atomic FeRh is a very interesting material as it undergoes a magnetostructural transition from an antiferromagnetic (AF) to a ferromagnetic (FM) phase between 75-105 °C. Its ability to present phase co-existence separated by domain walls (DWs) above room temperature provides immense potential for exploitation of their DW motion in spintronic devices. To be able to effectively control the DWs associated with AF/FM coexistence in FeRh thin films we must fully understand the magnetostructural transition and thermomagnetic behaviour of DWs at a localised scale. Here we present a transmission electron microscopy investigation of the transition in planar FeRh thin-film samples by combining differential phase contrast (DPC) magnetic imaging with in situ heating. We perform quantitative measurements from individual DWs as a function of temperature, showing that FeRh on NiAl exhibits thermomagnetic behaviour consistent with the transition from AF to FM. DPC imaging of an FeRh sample with HF-etched substrate reveals a state of AF/FM co-existence and shows the transition from AF to FM regions proceeds via nucleation of small vortex structures, which then grow by combining with newly nucleated vortex states into larger complex magnetic domains, until it is in a fully-FM state.
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Affiliation(s)
- Trevor P Almeida
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Rowan Temple
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Jamie Massey
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Kayla Fallon
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Thomas Moore
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | | | - Stephen McVitie
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
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18
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Mir J, Clough R, MacInnes R, Gough C, Plackett R, Shipsey I, Sawada H, MacLaren I, Ballabriga R, Maneuski D, O'Shea V, McGrouther D, Kirkland A. Characterisation of the Medipix3 detector for 60 and 80 keV electrons. Ultramicroscopy 2017; 182:44-53. [DOI: 10.1016/j.ultramic.2017.06.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/04/2017] [Accepted: 06/12/2017] [Indexed: 10/19/2022]
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19
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Goncalves FJT, Paterson GW, McGrouther D, Drysdale T, Togawa Y, Schmool DS, Stamps RL. Probing microwave fields and enabling in-situ experiments in a transmission electron microscope. Sci Rep 2017; 7:11064. [PMID: 28894134 PMCID: PMC5593874 DOI: 10.1038/s41598-017-11009-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/15/2017] [Indexed: 12/04/2022] Open
Abstract
A technique is presented whereby the performance of a microwave device is evaluated by mapping local field distributions using Lorentz transmission electron microscopy (L-TEM). We demonstrate the method by measuring the polarisation state of the electromagnetic fields produced by a microstrip waveguide as a function of its gigahertz operating frequency. The forward and backward propagating electromagnetic fields produced by the waveguide, in a specimen-free experiment, exert Lorentz forces on the propagating electron beam. Importantly, in addition to the mapping of dynamic fields, this novel method allows detection of effects of microwave fields on specimens, such as observing ferromagnetic materials at resonance.
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Affiliation(s)
- F J T Goncalves
- Department of Physics and Electronics, Osaka Prefecture University, Osaka, 599-8570, Japan.
- School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - G W Paterson
- School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - D McGrouther
- School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - T Drysdale
- Department of Engineering and Innovation, The Open University, Milton Keynes, MK7 6AA, UK
| | - Y Togawa
- Department of Physics and Electronics, Osaka Prefecture University, Osaka, 599-8570, Japan
- School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | - D S Schmool
- Groupe d'Etude de la Matière Condensée GEMaC, CNRS (UMR 8635), Université de Versailles/Saint-Quentin-en-Yvelines, 45 Avenue des États-Unis, 78035, Versailles, France
| | - R L Stamps
- School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
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20
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Lummen TTA, Lamb RJ, Berruto G, LaGrange T, Dal Negro L, García de Abajo FJ, McGrouther D, Barwick B, Carbone F. Imaging and controlling plasmonic interference fields at buried interfaces. Nat Commun 2016; 7:13156. [PMID: 27725670 PMCID: PMC5062594 DOI: 10.1038/ncomms13156] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 09/08/2016] [Indexed: 11/20/2022] Open
Abstract
Capturing and controlling plasmons at buried interfaces with nanometre and femtosecond resolution has yet to be achieved and is critical for next generation plasmonic devices. Here we use light to excite plasmonic interference patterns at a buried metal–dielectric interface in a nanostructured thin film. Plasmons are launched from a photoexcited array of nanocavities and their propagation is followed via photon-induced near-field electron microscopy (PINEM). The resulting movie directly captures the plasmon dynamics, allowing quantification of their group velocity at ∼0.3 times the speed of light, consistent with our theoretical predictions. Furthermore, we show that the light polarization and nanocavity design can be tailored to shape transient plasmonic gratings at the nanoscale. This work, demonstrating dynamical imaging with PINEM, paves the way for the femtosecond and nanometre visualization and control of plasmonic fields in advanced heterostructures based on novel two-dimensional materials such as graphene, MoS2, and ultrathin metal films. Visualizing surface plasmon polaritons at buried interfaces has remained elusive. Here, the authors develop a methodology to study the spatiotemporal evolution of buried near-fields within complex heterostructures, enabling the characterization of the next generation of plasmonic devices.
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Affiliation(s)
- Tom T A Lummen
- Laboratory for Ultrafast Microscopy and Electron Scattering, ICMP, École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - Raymond J Lamb
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - Gabriele Berruto
- Laboratory for Ultrafast Microscopy and Electron Scattering, ICMP, École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - Thomas LaGrange
- Interdisciplinary Center for Electron Microscopy (CIME), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Luca Dal Negro
- Department of Electrical and Computer Engineering and Photonics Center, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215, USA
| | - F Javier García de Abajo
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, 08860 Barcelona, Spain.,ICREA - Institució Catalana de Recerca i Estudis Avancats, Passeig Lluís Companys, 23, Barcelona 08010, Spain
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - B Barwick
- Department of Physics, Trinity College, 300 Summit Street, Hartford, Connecticut 06106, USA
| | - F Carbone
- Laboratory for Ultrafast Microscopy and Electron Scattering, ICMP, École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
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21
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Leonov AO, Togawa Y, Monchesky TL, Bogdanov AN, Kishine J, Kousaka Y, Miyagawa M, Koyama T, Akimitsu J, Koyama T, Harada K, Mori S, McGrouther D, Lamb R, Krajnak M, McVitie S, Stamps RL, Inoue K. Chiral Surface Twists and Skyrmion Stability in Nanolayers of Cubic Helimagnets. Phys Rev Lett 2016; 117:087202. [PMID: 27588877 DOI: 10.1103/physrevlett.117.087202] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Indexed: 06/06/2023]
Abstract
Theoretical analysis and Lorentz transmission electron microscopy (LTEM) investigations in an FeGe wedge demonstrate that chiral twists arising near the surfaces of noncentrosymmetric ferromagnets [Meynell et al., Phys. Rev. B 90, 014406 (2014)] provide a stabilization mechanism for magnetic Skyrmion lattices and helicoids in cubic helimagnet nanolayers. The magnetic phase diagram obtained for freestanding cubic helimagnet nanolayers shows that magnetization processes differ fundamentally from those in bulk cubic helimagnets and are characterized by the first-order transitions between modulated phases. LTEM investigations exhibit a series of hysteretic transformation processes among the modulated phases, which results in the formation of the multidomain patterns.
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Affiliation(s)
- A O Leonov
- Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- IFW Dresden, Postfach 270016, D-01171 Dresden, Germany
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands
| | - Y Togawa
- Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Osaka Prefecture University, 1-2 Gakuencho, Sakai, Osaka 599-8570, Japan
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
- JST, PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 333-0012, Japan
| | - T L Monchesky
- Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 3J5, Canada
| | - A N Bogdanov
- Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- IFW Dresden, Postfach 270016, D-01171 Dresden, Germany
| | - J Kishine
- Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- The Open University of Japan, Chiba 261-8586, Japan
| | - Y Kousaka
- Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - M Miyagawa
- Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - T Koyama
- Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - J Akimitsu
- Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Ts Koyama
- Osaka Prefecture University, 1-2 Gakuencho, Sakai, Osaka 599-8570, Japan
| | - K Harada
- Osaka Prefecture University, 1-2 Gakuencho, Sakai, Osaka 599-8570, Japan
| | - S Mori
- Osaka Prefecture University, 1-2 Gakuencho, Sakai, Osaka 599-8570, Japan
| | - D McGrouther
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - R Lamb
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - M Krajnak
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - S McVitie
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - R L Stamps
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - K Inoue
- Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- IAMR, Facility of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8530, Japan
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Krajnak M, McGrouther D, Maneuski D, Shea VO, McVitie S. Pixelated detectors and improved efficiency for magnetic imaging in STEM differential phase contrast. Ultramicroscopy 2016; 165:42-50. [DOI: 10.1016/j.ultramic.2016.03.006] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 03/08/2016] [Accepted: 03/22/2016] [Indexed: 11/26/2022]
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Benitez MJ, Hrabec A, Mihai AP, Moore TA, Burnell G, McGrouther D, Marrows CH, McVitie S. Magnetic microscopy and topological stability of homochiral Néel domain walls in a Pt/Co/AlOx trilayer. Nat Commun 2015; 6:8957. [PMID: 26642936 PMCID: PMC4686874 DOI: 10.1038/ncomms9957] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 10/20/2015] [Indexed: 11/09/2022] Open
Abstract
The microscopic magnetization variation in magnetic domain walls in thin films is a crucial property when considering the torques driving their dynamic behaviour. For films possessing out-of-plane anisotropy normally the presence of Néel walls is not favoured due to magnetostatic considerations. However, they have the right structure to respond to the torques exerted by the spin Hall effect. Their existence is an indicator of the interfacial Dzyaloshinskii-Moriya interaction (DMI). Here we present direct imaging of Néel domain walls with a fixed chirality in device-ready Pt/Co/AlOx films using Lorentz transmission electron and Kerr microscopies. It is shown that any independently nucleated pair of walls in our films form winding pairs when they meet that are difficult to annihilate with field, confirming that they all possess the same topological winding number. The latter is enforced by the DMI. The field required to annihilate these winding wall pairs is used to give a measure of the DMI strength. Such domain walls, which are robust against collisions with each other, are good candidates for dense data storage.
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Affiliation(s)
- M J Benitez
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, Scotland
| | - A Hrabec
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - A P Mihai
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - T A Moore
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - G Burnell
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - D McGrouther
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, Scotland
| | - C H Marrows
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - S McVitie
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, Scotland
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O'Shea KJ, MacLaren DA, McGrouther D, Schwarzbach D, Jungbauer M, Hühn S, Moshnyaga V, Stamps RL. Nanoscale Mapping of the Magnetic Properties of (111)-Oriented La(0.67)Sr(0.33)MnO3. Nano Lett 2015; 15:5868-74. [PMID: 26252745 DOI: 10.1021/acs.nanolett.5b01953] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Spatially resolved analysis of magnetic properties on the nanoscale remains challenging, yet strain and defects on this length-scale can profoundly affect a material's bulk performance. We present a detailed investigation of the magnetic properties of La0.67Sr0.33MnO3 thin films in both free-standing and nanowire form and assess the role of strain and local defects in modifying the films' magnetic properties. Lorentz transmission electron microscopy is used to measure the magnetocrystalline anisotropy and to map the Curie temperature and saturation magnetization with nanometric spatial resolution. Atomic-scale defects are identified as pinning sites for magnetic domain wall propagation. Measurement of domain wall widths and crystalline strain are used to identify a strong magnetoelastic contribution to the magnetic anisotropy. Together, these results provide unique insight into the relationship between the nanostructure and magnetic functionality of a ferromagnetic complex oxide film.
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Affiliation(s)
- Kerry J O'Shea
- SUPA, School of Physics and Astronomy, University of Glasgow , G12 8QQ, Glasgow, United Kingdom
| | - Donald A MacLaren
- SUPA, School of Physics and Astronomy, University of Glasgow , G12 8QQ, Glasgow, United Kingdom
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow , G12 8QQ, Glasgow, United Kingdom
| | - Danny Schwarzbach
- I. Physikalisches Institut, Georg-August-Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Markus Jungbauer
- I. Physikalisches Institut, Georg-August-Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sebastian Hühn
- I. Physikalisches Institut, Georg-August-Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Vasily Moshnyaga
- I. Physikalisches Institut, Georg-August-Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Robert L Stamps
- SUPA, School of Physics and Astronomy, University of Glasgow , G12 8QQ, Glasgow, United Kingdom
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MacLaren I, Wang L, McGrouther D, Craven AJ, McVitie S, Schierholz R, Kovács A, Barthel J, Dunin-Borkowski RE. On the origin of differential phase contrast at a locally charged and globally charge-compensated domain boundary in a polar-ordered material. Ultramicroscopy 2015; 154:57-63. [DOI: 10.1016/j.ultramic.2015.03.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/09/2015] [Accepted: 03/18/2015] [Indexed: 11/27/2022]
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26
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O'Shea KJ, McGrouther D, Ferguson CA, Jungbauer M, Hühn S, Moshnyaga V, MacLaren DA. Fabrication of high quality plan-view TEM specimens using the focused ion beam. Micron 2014; 66:9-15. [PMID: 25080271 DOI: 10.1016/j.micron.2014.04.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 04/24/2014] [Accepted: 04/24/2014] [Indexed: 10/25/2022]
Abstract
We describe a technique using a focused ion beam instrument to fabricate high quality plan-view specimens for transmission electron microscopy studies. The technique is simple, site-specific and is capable of fabricating multiple large, >100 μm(2) electron transparent windows within epitaxially grown thin films. A film of La0.67Sr0.33MnO3 is used to demonstrate the technique and its structural and functional properties are surveyed by high resolution imaging, electron spectroscopy, atomic force microscopy and Lorentz electron microscopy. The window is demonstrated to have good thickness uniformity and a low defect density that does not impair the film's Curie temperature. The technique will enable the study of in-plane structural and functional properties of a variety of epitaxial thin film systems.
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Affiliation(s)
- K J O'Shea
- SUPA, School of Physics and Astronomy, University of Glasgow, G12 8QQ, UK.
| | - D McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, G12 8QQ, UK
| | - C A Ferguson
- SUPA, School of Physics and Astronomy, University of Glasgow, G12 8QQ, UK
| | - M Jungbauer
- University of Gottingen, Institute Physics 1, Friedrich Hund Pl 1, D-37077 Gottingen, Germany
| | - S Hühn
- University of Gottingen, Institute Physics 1, Friedrich Hund Pl 1, D-37077 Gottingen, Germany
| | - V Moshnyaga
- University of Gottingen, Institute Physics 1, Friedrich Hund Pl 1, D-37077 Gottingen, Germany
| | - D A MacLaren
- SUPA, School of Physics and Astronomy, University of Glasgow, G12 8QQ, UK
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27
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O’Shea KJ, Bova K, McGrouther D, MacLaren DA. Investigating the effect of a stress-based uniaxial anisotropy on the magnetic behaviour of La0.7Sr0.3MnO3elements. EPJ Web of Conferences 2014. [DOI: 10.1051/epjconf/20147505017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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28
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Payraudeau N, McGrouther D, O'Kelly KU. Quantification of subsurface damage in a brittle insulating ceramic by three-dimensional focused ion beam tomography. Microsc Microanal 2011; 17:240-245. [PMID: 21371371 DOI: 10.1017/s1431927610094523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this study, we present a fully automated method to investigate and reconstruct the three-dimensional crack structure beneath an indent in a highly insulating material. This work concentrates on issues arising from a long automatic acquisition process, the insulating nature of the specimen, and the introduction of minimal damage to the original cracks resulting from indentation.
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Affiliation(s)
- N Payraudeau
- Department of Mechanical and Manufacturing Engineering, Trinity College Dublin, Dublin 2, Ireland.
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29
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Abstract
AbstractThe response of crystalline Ge to indentation has been studied over a range of maximum loads. At a certain load, an unusual ‘giant pop-in’ event occurs, in which a discontinuous extension of >1 μm is observed in the force-displacement curve. In such cases, load release curves show a pronounced ‘elbowing’ response, leading to increased depth recovery. TEM and Raman microspectroscopy revealed the presence of amorphous material in the residual impression. To examine cracking, a sequence of cross-sections was milled through the indent and images taken using an automated method (the ‘slice-and-view’ method). Using 3-D reconstruction software, the data was segmented and reconstructed into a 3-dimensional representation of the cracks around the indent. Applying this technique to indents featuring a giant pop-in, it was deduced that the inelastic elbowing observed was a bending response of material detached by lateral cracking. The giant pop-in is attributable to material removal, caused by lateral cracks formed during loading.
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30
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Bode M, Pietzsch O, Kubetzka A, Wulfhekel W, McGrouther D, McVitie S, Chapman JN. Comment on "three-dimensional, spin-resolved structure of magnetic vortex and antivortex states in patterned co films using scanning ion microscopy with polarization analysis". Phys Rev Lett 2008; 100:029703. [PMID: 18232943 DOI: 10.1103/physrevlett.100.029703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Indexed: 05/25/2023]
Affiliation(s)
- M Bode
- Institute of Applied Physics and Microstructure Research Center University of Hamburg Hamburg, Germany
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31
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Abstract
A dual FIB/SEM provides solutions to many challenges in atom probe specimen preparation. When combined with an in situ lift-out capability, the versatility of this tool allows almost any region of interest, in almost any geometry, to be placed at the apex of a specimen tip. Several preparation techniques have been developed in response to specific application requirements; for example, in cases where materials are not suitable for electropolishing, or where site-specific analysis is required. Two general techniques, with wide-ranging potential applications, are described in detail here. The first is a 'cut-out' technique that provides a relatively quick means of micro-tip specimen preparation from bulk material samples. The second method is a 'lift-out' technique that can be used in an in situ or ex situ mode and does not require the preparation of pre-sharpened mounting points.
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Affiliation(s)
- D W Saxey
- Australian Key Centre for Microscopy & Microanalysis, University of Sydney, Sydney, NSW 2006, Australia.
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32
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Abstract
The application of focused ion beam instrumentation in the generation of three-dimensional microstructural data is described. The methodologies used to acquire and manipulate this data are explained, and the technique is illustrated by a number of examples from the material sciences. The limitations of this method, and practical pointers to the generation of meaningful data, are also discussed.
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Affiliation(s)
- D McGrouther
- Electron Microscope Unit, University of New South Wales, Sydney, New South Wales, Australia
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Hormbrey E, Gillespie P, Turner K, Han C, Roberts A, McGrouther D, Harris AL. A critical review of vascular endothelial growth factor (VEGF) analysis in peripheral blood: is the current literature meaningful? Clin Exp Metastasis 2003; 19:651-63. [PMID: 12553370 DOI: 10.1023/a:1021379811308] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Vascular endothelial growth factor (VEGF) is a potent angiogenic growth factor with a key role in many physiological and pathological processes. Investigation into the implications of circulating levels of this cytokine is progressing at an exponential rate. However, there are important inconsistencies between reports ranging from method of sample collection, processing, software manipulation and data interpretation and controversy as to whether plasma, serum or whole blood will provide the best prognostic information. Different techniques of centrifugation and temperature on sample handling and the impact of in vitro collection of blood on subsequent VEGF results have not been fully appreciated. We provide a critical review of the literature, report the results of our further investigations, suggest a uniform protocol for handling blood samples and highlight previously unsuspected problems in data interpretation.
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Affiliation(s)
- E Hormbrey
- Weatherall Institute of Molecular Medicine, Headington, Oxford, UK
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Abstract
Specimens of hypertrophic scar tissue (n = 9), non-hypertrophic, flat scar tissue (n = 5) and control skin (n = 3) were obtained from eight adult females (aged 22-56) and three adult males (aged 22-59). The specimens were studied histologically and immunohistochemically for vasoactive intestinal polypeptide, neuropeptide Y, calcitonin gene-related peptide, substance P, somatostatin, [Met]enkephalin, [Leu]enkephalin, and the enzyme dopamine beta-hydroxylase. The non-hypertrophic scar tissues were not dissimilar to the control tissue, but contained connective tissue in bundles with a greater number of collagen fibres. In the hypertrophic scar tissue of some patients, the dermis contained adipose tissue displaced upwards from the hypodermis. The connective tissue contained densely packed collagen fibres and fibroblasts; this region was devoid of hair follicles, sweat glands and blood vessels, although they were observed in the region of loosely packed connective tissue. The normal skin contained all the neuropeptides studied, except somatostatin-, and dopamine beta-hydroxylase-immunoreactive nerves, which were seen as single fibres or in nerve bundles, and were associated with blood vessels in the dermis. Neuropeptide Y-immunoreactive nerves were found in the arrector pili muscle, and neuropeptide Y-, vasoactive intestinal polypeptide-, calcitonin gene-related peptide-, [Met]enkephalin- and dopamine beta-hydroxylase-containing nerves were found within sweat glands. In patients with flat, non-hypertrophic scar tissue, neuropeptides and dopamine beta-hydroxylase-containing nerves were absent. In patients with hypertrophic scars, the density of neuropeptide Y-, vasoactive intestinal polypeptide-, substance P-, calcitonin gene-related peptide- and dopamine beta-hydroxylase-immunoreactive nerves was greater in the dermis when compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R Crowe
- Department of Anatomy and Developmental Biology, University College London, U.K
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