1
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Betal S, Bhalla AS, Guo R. High-speed propulsion of magnetoelectric nanovehicle actuated by bio-cellular electric field sensing. SENSING AND BIO-SENSING RESEARCH 2022. [DOI: 10.1016/j.sbsr.2022.100521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/15/2022] Open
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2
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Synergistic use of gradient flipping and phase prediction for inline electron holography. Sci Rep 2022; 12:13294. [PMID: 35918369 PMCID: PMC9345894 DOI: 10.1038/s41598-022-17373-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 07/25/2022] [Indexed: 11/15/2022] Open
Abstract
Inline holography in the transmission electron microscope is a versatile technique which provides real-space phase information that can be used for the correction of imaging aberrations, as well as for measuring electric and magnetic fields and strain distributions. It is able to recover high-spatial-frequency contributions of the phase effectively but suffers from the weak transfer of low-spatial-frequency information, as well as from incoherent scattering. Here, we combine gradient flipping and phase prediction in an iterative flux-preserving focal series reconstruction algorithm with incoherent background subtraction that gives extensive access to the missing low spatial frequencies. A procedure for optimizing the reconstruction parameters is presented, and results from Fe-filled C nanospheres, and MgO cubes are compared with phase images obtained using off-axis holography.
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3
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Amor M, Wan J, Egli R, Carlut J, Gatel C, Andersen IM, Snoeck E, Komeili A. Key Signatures of Magnetofossils Elucidated by Mutant Magnetotactic Bacteria and Micromagnetic Calculations. JOURNAL OF GEOPHYSICAL RESEARCH. SOLID EARTH 2022; 127:e2021JB023239. [PMID: 35444924 PMCID: PMC9017866 DOI: 10.1029/2021jb023239] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/30/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
Magnetotactic bacteria (MTB) produce single-stranded or multi-stranded chains of magnetic nanoparticles that contribute to the magnetization of sediments and rocks. Their magnetic fingerprint can be detected in ancient geological samples and serve as a unique biosignature of microbial life. However, some fossilized assemblages bear contradictory signatures pointing to magnetic components that have distinct origin(s). Here, using micromagnetic simulations and mutant MTB producing looped magnetosome chains, we demonstrate that the observed magnetofossil fingerprints are produced by a mixture of single-stranded and multi-stranded chains, and that diagenetically induced chain collapse, if occurring, must preserve the strong uniaxial anisotropy of native chains. This anisotropy is the key factor for distinguishing magnetofossils from other populations of natural magnetite particles, including those with similar individual crystal characteristics. Furthermore, the detailed properties of magnetofossil signatures depend on the proportion of equant and elongated magnetosomes, as well as on the relative abundances of single-stranded and multi-stranded chains. This work has important paleoclimatic, paleontological, and phylogenetic implications, as it provides reference data to differentiate distinct MTB lineages according to their chain and magnetosome morphologies, which will enable the tracking of the evolution of some of the most ancient biomineralizing organisms in a time-resolved manner. It also enables a more accurate discrimination of different sources of magnetite particles, which is pivotal for gaining better environmental and relative paleointensity reconstructions from sedimentary records.
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Affiliation(s)
- Matthieu Amor
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCAUSA
- Aix‐Marseille Université, CEA, CNRS, BIAMSaint‐Paul‐lez‐DuranceFrance
| | - Juan Wan
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCAUSA
| | - Ramon Egli
- Zentralanstalt für Meteorologie und Geodynamik (ZAMG)ViennaAustria
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Julie Carlut
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | | | | | | | - Arash Komeili
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCAUSA
- Department of Molecular and Cell BiologyUniversity of CaliforniaBerkeleyCAUSA
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4
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Abstract
Abstract
Deep learning is transforming most areas of science and technology, including electron microscopy. This review paper offers a practical perspective aimed at developers with limited familiarity. For context, we review popular applications of deep learning in electron microscopy. Following, we discuss hardware and software needed to get started with deep learning and interface with electron microscopes. We then review neural network components, popular architectures, and their optimization. Finally, we discuss future directions of deep learning in electron microscopy.
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5
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López-Conesa L, Martínez-Boubeta C, Serantes D, Estradé S, Peiró F. Mapping the Magnetic Coupling of Self-Assembled Fe 3O 4 Nanocubes by Electron Holography. MATERIALS 2021; 14:ma14040774. [PMID: 33562117 PMCID: PMC7915427 DOI: 10.3390/ma14040774] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/18/2021] [Accepted: 02/03/2021] [Indexed: 01/21/2023]
Abstract
The nanoscale magnetic configuration of self-assembled groups of magnetite 40 nm cubic nanoparticles has been investigated by means of electron holography in the transmission electron microscope (TEM). The arrangement of the cubes in the form of chains driven by the alignment of their dipoles of single nanocubes is assessed by the measured in-plane magnetic induction maps, in good agreement with theoretical calculations.
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Affiliation(s)
- Lluís López-Conesa
- Laboratory of Electron Nanoscopies (LENS-MIND), Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, 08028 Barcelona, Spain; (S.E.); (F.P.)
- Institute of Nanoscience and Nanotechnology, Universtitat de Barcelona, (IN2UB), 08028 Barcelona, Spain
- Centres Científics i Tecnològics de la Universitat de Barcelona (CCiTUB), 08028 Barcelona, Spain
- Correspondence:
| | | | - David Serantes
- Instituto de Investigacións Tecnolóxicas and Departamento de Física Aplicada, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain;
| | - Sonia Estradé
- Laboratory of Electron Nanoscopies (LENS-MIND), Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, 08028 Barcelona, Spain; (S.E.); (F.P.)
- Institute of Nanoscience and Nanotechnology, Universtitat de Barcelona, (IN2UB), 08028 Barcelona, Spain
| | - Francesca Peiró
- Laboratory of Electron Nanoscopies (LENS-MIND), Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, 08028 Barcelona, Spain; (S.E.); (F.P.)
- Institute of Nanoscience and Nanotechnology, Universtitat de Barcelona, (IN2UB), 08028 Barcelona, Spain
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6
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Pierobon L, Kovács A, Schäublin RE, Gerstl SSA, Caron J, Wyss UV, Dunin-Borkowski RE, Löffler JF, Charilaou M. Unconventional magnetization textures and domain-wall pinning in Sm-Co magnets. Sci Rep 2020; 10:21209. [PMID: 33273594 PMCID: PMC7713442 DOI: 10.1038/s41598-020-78010-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 11/19/2020] [Indexed: 11/21/2022] Open
Abstract
Some of the best-performing high-temperature magnets are Sm–Co-based alloys with a microstructure that comprises an \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Sm}_2\hbox {Co}_{17}$$\end{document}Sm2Co17 matrix and magnetically hard \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {SmCo}_5$$\end{document}SmCo5 cell walls. This generates a dense domain-wall-pinning network that endows the material with remarkable magnetic hardness. A precise understanding of the coupling between magnetism and microstructure is essential for enhancing the performance of Sm–Co magnets, but experiments and theory have not yet converged to a unified model. Here, transmission electron microscopy, atom probe tomography, and nanometer-resolution off-axis electron holography have been combined with micromagnetic simulations to reveal that the magnetization state in Sm–Co magnets results from curling instabilities and domain-wall pinning effects at the intersections of phases with different magnetic hardness. Additionally, this study has found that topologically non-trivial magnetic domains separated by a complex network of domain walls play a key role in the magnetic state by acting as nucleation sites for magnetization reversal. These findings reveal previously hidden aspects of magnetism in Sm–Co magnets and, by identifying weak points in the microstructure, provide guidelines for improving these high-performance magnetic materials.
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Affiliation(s)
- Leonardo Pierobon
- Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland.
| | - András Kovács
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, and Peter Grünberg Institute, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Robin E Schäublin
- Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland.,Scientific Center for Optical and Electron Microscopy, ETH Zurich, 8093, Zurich, Switzerland
| | - Stephan S A Gerstl
- Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland.,Scientific Center for Optical and Electron Microscopy, ETH Zurich, 8093, Zurich, Switzerland
| | - Jan Caron
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, and Peter Grünberg Institute, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Urs V Wyss
- Arnold Magnetic Technologies, 5242, Birr-Lupfig, Switzerland
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, and Peter Grünberg Institute, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Jörg F Löffler
- Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland.
| | - Michalis Charilaou
- Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland. .,Department of Physics, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA.
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7
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Boureau V, Nguyen VD, Masseboeuf A, Palomino A, Gautier E, Chatterjee J, Lequeux S, Auffret S, Vila L, Sousa R, Prejbeanu L, Cooper D, Dieny B. An electron holography study of perpendicular magnetic tunnel junctions nanostructured by deposition on pre-patterned conducting pillars. NANOSCALE 2020; 12:17312-17318. [PMID: 32789322 DOI: 10.1039/d0nr03353g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The fabrication of multi-gigabit magnetic random access memory (MRAM) chips requires the patterning of magnetic tunnel junctions at very small dimensions (sub-30 nm) and a very dense pitch. This remains a challenge due to the difficulty in etching magnetic tunnel junction stacks. We previously proposed a strategy to circumvent this problem by depositing the magnetic tunnel junction material on prepatterned metallic pillars, resulting in the junction being naturally shaped during deposition. Upon electrical contact, the deposit on top of the pillars constitutes the magnetic storage element of the memory cell. However, in this process, the magnetic material is also deposited in the trenches between the pillars that might affect the memory cell behaviour. Here we study the magnetic interactions between the deposit on top of the pillars and in the trenches by electron holography, at room temperature and up to 325 °C. Supported by models, we show that the additional material in the trenches is not perturbing the working principle of the memory chip and can even play the role of a flux absorber which reduces the crosstalk between neighboring dots. Besides, in the studied sample, the magnetization of the 1.4 nm thick storage layer of the dots is found to switch from out-of-plane to an in-plane configuration above 125 °C, but gradually decreases with temperature. Electron holography is shown to constitute a very efficient tool for characterizing the micromagnetic configuration of the storage layer in MRAM cells.
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Affiliation(s)
- V Boureau
- Univ. Grenoble Alpes, CEA-LETI, F-38000 Grenoble, France.
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8
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Gregurec D, Senko AW, Chuvilin A, Reddy PD, Sankararaman A, Rosenfeld D, Chiang PH, Garcia F, Tafel I, Varnavides G, Ciocan E, Anikeeva P. Magnetic Vortex Nanodiscs Enable Remote Magnetomechanical Neural Stimulation. ACS NANO 2020; 14:8036-8045. [PMID: 32559057 PMCID: PMC8592276 DOI: 10.1021/acsnano.0c00562] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Magnetic nanomaterials in magnetic fields can serve as versatile transducers for remote interrogation of cell functions. In this study, we leveraged the transition from vortex to in-plane magnetization in iron oxide nanodiscs to modulate the activity of mechanosensory cells. When a vortex configuration of spins is present in magnetic nanomaterials, it enables rapid control over their magnetization direction and magnitude. The vortex configuration manifests in near zero net magnetic moment in the absence of a magnetic field, affording greater colloidal stability of magnetic nanomaterials in suspensions. Together, these properties invite the application of magnetic vortex particles as transducers of externally applied minimally invasive magnetic stimuli in biological systems. Using magnetic modeling and electron holography, we predict and experimentally demonstrate magnetic vortex states in an array of colloidally synthesized magnetite nanodiscs 98-226 nm in diameter. The magnetic nanodiscs applied as transducers of torque for remote control of mechanosensory neurons demonstrated the ability to trigger Ca2+ influx in weak (≤28 mT), slowly varying (≤5 Hz) magnetic fields. The extent of cellular response was determined by the magnetic nanodisc volume and magnetic field conditions. Magnetomechanical activation of a mechanosensitive cation channel TRPV4 (transient receptor potential vanilloid family member 4) exogenously expressed in the nonmechanosensitive HEK293 cells corroborated that the stimulation is mediated by mechanosensitive ion channels. With their large magnetic torques and colloidal stability, magnetic vortex particles may facilitate basic studies of mechanoreception and its applications to control electroactive cells with remote magnetic stimuli.
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Affiliation(s)
- Danijela Gregurec
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alexander W Senko
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Andrey Chuvilin
- CIC nanoGUNE, E20018 San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | - Pooja D Reddy
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ashwin Sankararaman
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Dekel Rosenfeld
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Po-Han Chiang
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Francisco Garcia
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ian Tafel
- Department of Neurosurgery, Brigham and Women's Hospital, Boston, Massachusetts 02115, United States
| | - Georgios Varnavides
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Eugenia Ciocan
- Department of Engineering and Physical Sciences, Bunker Hill Community College, Boston, Massachusetts 02129, United States
| | - Polina Anikeeva
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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9
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Jaafar M, Pablo-Navarro J, Berganza E, Ares P, Magén C, Masseboeuf A, Gatel C, Snoeck E, Gómez-Herrero J, de Teresa JM, Asenjo A. Customized MFM probes based on magnetic nanorods. NANOSCALE 2020; 12:10090-10097. [PMID: 32348391 DOI: 10.1039/d0nr00322k] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Focused Electron Beam Induced Deposition (FEBID) for magnetic tip fabrication is presented in this work as an alternative to conventional sputtering-based Magnetic Force Microscopy (MFM) tips. FEBID enables the growth of a high-aspect-ratio magnetic nanorod with customized geometry and composition to overcome the key technical limitations of MFM probes currently on the market. The biggest advantage of these tips, in comparison with CoCr coated pyramidal probes, lies in the capability of creating sharp ends, nearly 10 nm in diameter, which provides remarkable (topographic and magnetic) lateral resolution in samples with magnetic features close to the resolution limits of the MFM technique itself. The shape of the nanorods produces a very confined magnetic stray field, whose interaction with the sample is extremely localized and perpendicular to the surface, with negligible in-plane components. This effect can lead to a better analytical and numerical modelling of the MFM probes and to an increase in the sensitivity without perturbing the magnetic configuration of soft samples. Besides, the high-aspect ratio achievable in FEBID nanorod tips makes them magnetically harder than the commercial ones, reaching coercive fields higher than 900 Oe. According to the results shown, tips based on magnetic nanorods grown by FEBID can be eventually used for quantitative analysis in MFM measurements. Moreover, the customized growth of Co- or Fe-based tips onto levers with different mechanical properties allows MFM studies that demand different measuring conditions. To showcase the versatility of this type of probe, as a last step, MFM is performed in a liquid environment, which still remains a challenge for the MFM community largely due to the lack of appropriate probes on the market. This opens up new possibilities in the investigation of magnetic biological samples.
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Affiliation(s)
- Miriam Jaafar
- Departamento de Física de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain.
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10
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Iacovita C, Hurst J, Manfredi G, Hervieux PA, Donnio B, Gallani JL, Rastei MV. Magnetic force fields of isolated small nanoparticle clusters. NANOSCALE 2020; 12:1842-1851. [PMID: 31899471 DOI: 10.1039/c9nr08634j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The usage of magnetic nanoparticles (NPs) in applications necessitates a precise mastering of their properties at the single nanoparticle level. There has been a lot of progress in the understanding of the magnetic properties of NPs, but incomparably less when interparticle interactions govern the overall magnetic response. Here, we present a quantitative investigation of magnetic fields generated by small clusters of NPs assembled on a dielectric non-magnetic surface. Structures ranging from individual NPs to fifth-fold particulate clusters are investigated in their magnetization saturation state by magnetic force microscopy and numerical calculations. It is found that the magnetic stray field does not increase proportionally with the number of NPs in the cluster. Both measured and calculated magnetic force fields underline the great importance of the exact spatial arrangement of NPs, shedding light on the magnetic force field distribution of particulate clusters, which is relevant for the quantitative evaluation of their magnetization and perceptibly for many applications.
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Affiliation(s)
- C Iacovita
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, Université de Strasbourg, F-67034 Strasbourg, France.
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11
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Csörgö T, Novák T, Pasechnik R, Ster A, Szanyi I. Proton Holography Discovering Odderon from Scaling Properties of Elastic Scattering. EPJ WEB OF CONFERENCES 2020. [DOI: 10.1051/epjconf/202023506002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We investigate the scaling properties of elastic scattering data at ISR and LHC energies, and find that the significance of an Odderon observation is larger than the discovery threshold of 5σ. As an unexpected by-product of these investigations, for certain experimentally relevant cases, we also conjecture the possibility of proton holography with the help of elastic proton-proton scattering.
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12
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13
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Off-axis electron holography combining summation of hologram series with double-exposure phase-shifting: Theory and application. Ultramicroscopy 2018; 193:52-63. [DOI: 10.1016/j.ultramic.2018.06.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/30/2018] [Accepted: 06/03/2018] [Indexed: 11/23/2022]
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14
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Magnetic-field induced rotation of magnetosome chains in silicified magnetotactic bacteria. Sci Rep 2018; 8:7699. [PMID: 29769616 PMCID: PMC5955880 DOI: 10.1038/s41598-018-25972-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 04/19/2018] [Indexed: 11/21/2022] Open
Abstract
Understanding the biological processes enabling magnetotactic bacteria to maintain oriented chains of magnetic iron-bearing nanoparticles called magnetosomes is a major challenge. The study aimed to constrain the role of an external applied magnetic field on the alignment of magnetosome chains in Magnetospirillum magneticum AMB-1 magnetotactic bacteria immobilized within a hydrated silica matrix. A deviation of the chain orientation was evidenced, without significant impact on cell viability, which was preserved after the field was turned-off. Transmission electron microscopy showed that the crystallographic orientation of the nanoparticles within the chains were preserved. Off-axis electron holography evidenced that the change in magnetosome orientation was accompanied by a shift from parallel to anti-parallel interactions between individual nanocrystals. The field-induced destructuration of the chain occurs according to two possible mechanisms: (i) each magnetosome responds individually and reorients in the magnetic field direction and/or (ii) short magnetosome chains deviate in the magnetic field direction. This work enlightens the strong dynamic character of the magnetosome assembly and widens the potentialities of magnetotactic bacteria in bionanotechnology.
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15
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Song D, Li ZA, Caron J, Kovács A, Tian H, Jin C, Du H, Tian M, Li J, Zhu J, Dunin-Borkowski RE. Quantification of Magnetic Surface and Edge States in an FeGe Nanostripe by Off-Axis Electron Holography. PHYSICAL REVIEW LETTERS 2018; 120:167204. [PMID: 29756913 DOI: 10.1103/physrevlett.120.167204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 12/13/2017] [Indexed: 06/08/2023]
Abstract
Whereas theoretical investigations have revealed the significant influence of magnetic surface and edge states on Skyrmonic spin texture in chiral magnets, experimental studies of such chiral states remain elusive. Here, we study chiral edge states in an FeGe nanostripe experimentally using off-axis electron holography. Our results reveal the magnetic-field-driven formation of chiral edge states and their penetration lengths at 95 and 240 K. We determine values of saturation magnetization M_{S} by analyzing the projected in-plane magnetization distributions of helices and Skyrmions. Values of M_{S} inferred for Skyrmions are lower by a few percent than those for helices. We attribute this difference to the presence of chiral surface states, which are predicted theoretically in a three-dimensional Skyrmion model. Our experiments provide direct quantitative measurements of magnetic chiral boundary states and highlight the applicability of state-of-the-art electron holography for the study of complex spin textures in nanostructures.
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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, 100084 Beijing, China
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Zi-An Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190 Beijing, China
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Jan Caron
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - András Kovács
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Huanfang Tian
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190 Beijing, China
| | - Chiming Jin
- High Magnetic Field Laboratory, Chinese Academy of Sciences, 230031 Anhui, China
| | - Haifeng Du
- High Magnetic Field Laboratory, Chinese Academy of Sciences, 230031 Anhui, China
| | - Mingliang Tian
- High Magnetic Field Laboratory, Chinese Academy of Sciences, 230031 Anhui, China
| | - Jianqi Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190 Beijing, 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, 100084 Beijing, China
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
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16
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Venturi F, Gazzadi GC, Tavabi AH, Rota A, Dunin-Borkowski RE, Frabboni S. Magnetic characterization of cobalt nanowires and square nanorings fabricated by focused electron beam induced deposition. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:1040-1049. [PMID: 29719756 PMCID: PMC5905252 DOI: 10.3762/bjnano.9.97] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 02/28/2018] [Indexed: 06/08/2023]
Abstract
The magnetic properties of nanowires (NWs) and square nanorings, which were deposited by focused electron beam induced deposition (FEBID) of a Co carbonyl precursor, are studied using off-axis electron holography (EH), Lorentz transmission electron microscopy (L-TEM) and magnetic force microscopy (MFM). EH shows that NWs deposited using beam energies of 5 and 15 keV have the characteristics of magnetic dipoles, with larger magnetic moments observed for NWs deposited at lower energy. L-TEM is used to image magnetic domain walls in NWs and nanorings and their motion as a function of applied magnetic field. The NWs are found to have almost square hysteresis loops, with coercivities of ca. 10 mT. The nanorings show two different magnetization states: for low values of the applied in-plane field (0.02 T) a horseshoe state is observed using L-TEM, while for higher values of the applied in-plane field (0.3 T) an onion state is observed at remanence using L-TEM and MFM. Our results confirm the suitability of FEBID for nanofabrication of magnetic structures and demonstrate the versatility of TEM techniques for the study and manipulation of magnetic domain walls in nanostructures.
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Affiliation(s)
- Federico Venturi
- FIM Department, University of Modena and Reggio Emilia, Via G. Campi 213/a, Modena I-41125, Italy
- CNR – Nanoscience Institute, S3 Center, Via G. Campi 213/a, Modena I-41125, Italy
| | - Gian Carlo Gazzadi
- CNR – Nanoscience Institute, S3 Center, Via G. Campi 213/a, Modena I-41125, Italy
| | - Amir H Tavabi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Alberto Rota
- Intermech-Mo.Re. Center, University of Modena and Reggio Emilia, Via Vignolese 905/b, Modena I-41125, Italy
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Stefano Frabboni
- FIM Department, University of Modena and Reggio Emilia, Via G. Campi 213/a, Modena I-41125, Italy
- CNR – Nanoscience Institute, S3 Center, Via G. Campi 213/a, Modena I-41125, Italy
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17
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Core-shell magnetoelectric nanorobot - A remotely controlled probe for targeted cell manipulation. Sci Rep 2018; 8:1755. [PMID: 29379076 PMCID: PMC5788862 DOI: 10.1038/s41598-018-20191-w] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 01/16/2018] [Indexed: 01/16/2023] Open
Abstract
We have developed a remotely controlled dynamic process of manipulating targeted biological live cells using fabricated core-shell nanocomposites, which comprises of single crystalline ferromagnetic cores (CoFe2O4) coated with crystalline ferroelectric thin film shells (BaTiO3). We demonstrate them as a unique family of inorganic magnetoelectric nanorobots (MENRs), controlled remotely by applied a.c. or d.c. magnetic fields, to perform cell targeting, permeation, and transport. Under a.c. magnetic field excitation (50 Oe, 60 Hz), the MENR acts as a localized electric periodic pulse generator and can permeate a series of misaligned cells, while aligning them to an equipotential mono-array by inducing inter-cellular signaling. Under a.c. magnetic field (40 Oe, 30 Hz) excitation, MENRs can be dynamically driven to a targeted cell, avoiding untargeted cells in the path, irrespective of cell density. D.C. magnetic field (−50 Oe) excitation causes the MENRs to act as thrust generator and exerts motion in a group of cells.
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18
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Kovács A, Dunin-Borkowski RE. Magnetic Imaging of Nanostructures Using Off-Axis Electron Holography. HANDBOOK OF MAGNETIC MATERIALS 2018. [DOI: 10.1016/bs.hmm.2018.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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19
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Clifford DM, Castano CE, Tsui MHM, Rojas JV, Carpenter EE. Tailoring the magnetic properties of Fe xCo (1-x) nanopowders prepared by a polyol process. Dalton Trans 2017; 46:10364-10373. [PMID: 28745350 DOI: 10.1039/c7dt01691c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Precise control over the magnetic properties of FeCo alloys is of scientific significance, due to their high Curie points and saturation magnetizations, and of broad interest for applications such as transformer cores, induction motors, switching devices, and hyperthermia. The magnetic properties of FexCo(1-x) alloy-based nanopowders prepared by polyol synthesis and their relationship with morphological features and the evolution of the microstructure were investigated using a design of experiments (DoE) approach. Proportionalities related to the magnetic properties, saturation magnetization (Ms) and coercivity (Hc), were identified where Ms ∝ (110) crystallite size of FeCo (bcc) and Hc ∝ particle diameter for the as-synthesized FexCo(1-x) nanopowders. Adjusting the reaction composition allows for control of the FeCo (bcc) (110) crystallite size from 20-45 nm represented by a response surface model. Morphological features of the as-synthesized nanopowders include particles interlinked as chains, and particles either in the form of cuboids or spheroids, all with diameters ranging from 75-175 nm. FexCo(1-x) alloy was confirmed by XRD in each nanopowder while few contained a combination of phases which include Co (fcc), or ferrite (CoFe2O4), or both. Depending on composition, particle dimension, and microstructure, the Ms ranged from 90-215 emu g-1 with Hc from 90-400 Oe for all nanopowders synthesized by the sub-reflux, isothermal condition (150 °C). Tailoring the magnetic properties of FexCo(1-x) alloy-based nanopowders is accomplished chemically by identifying and regulating significant reaction parameters and conditions.
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Affiliation(s)
- Dustin M Clifford
- Dept. of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
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20
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Röder F, Vogel K, Wolf D, Hellwig O, Wee SH, Wicht S, Rellinghaus B. Model-based magnetization retrieval from holographic phase images. Ultramicroscopy 2017; 176:177-187. [DOI: 10.1016/j.ultramic.2016.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 10/28/2016] [Accepted: 11/03/2016] [Indexed: 10/20/2022]
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21
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Akhtari-Zavareh A, De Graef M, Kavanagh KL. Magnetic phase shift reconstruction for uniformly magnetized nanowires. Ultramicroscopy 2016; 172:10-16. [PMID: 27744132 DOI: 10.1016/j.ultramic.2016.10.002] [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: 07/25/2016] [Revised: 09/13/2016] [Accepted: 10/02/2016] [Indexed: 10/20/2022]
Abstract
A new analytical model is developed for the magnetic phase shift of uniformly magnetized nanowires with ideal cylindrical geometry. The model is applied to experimental data from off-axis electron holography measurements of the phase shift of CoFeB nanowires, and the saturation induction of a selected wire, as well as its radius, aspect ratio, position and orientation, is determined by fitting the model parameters. The saturation induction value of 1.7T of the CoFeB nanowire is found to be similar, to be within the measurement error, to values reported in the literature.
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Affiliation(s)
| | - Marc De Graef
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Karen L Kavanagh
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada
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22
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Zweck J. Imaging of magnetic and electric fields by electron microscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:403001. [PMID: 27536873 DOI: 10.1088/0953-8984/28/40/403001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Nanostructured materials become more and more a part of our daily life, partly as self-assembled particles or artificially patterned. These nanostructures often possess intrinsic magnetic and/or electric fields which determine (at least partially) their physical properties. Therefore it is important to be able to measure these fields reliably on a nanometre scale. A rather common instrument for the investigation of these fields is the transmission electron microscope as it offers high spatial resolution. The use of an electron microscope to image electric and magnetic fields on a micron down to sub-nanometre scale is treated in detail for transmission electron microscopes (TEM) and scanning transmission electron microscopes (STEM). The formation of contrast is described for the most common imaging modes, the specific advantages and disadvantages of each technique are discussed and examples are given. In addition, the experimental requirements for the use of the techniques described are listed and explained.
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Affiliation(s)
- Josef Zweck
- Physics Faculty, University of Regensburg, Electron Microscopy Laboratory, 93040 Regensburg, Universitätsstrasse 31, Germany
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23
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Phatak C, de Knoop L, Houdellier F, Gatel C, Hÿtch MJ, Masseboeuf A. Quantitative 3D electromagnetic field determination of 1D nanostructures from single projection. Ultramicroscopy 2016; 164:24-30. [PMID: 26998702 DOI: 10.1016/j.ultramic.2016.03.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 03/07/2016] [Accepted: 03/09/2016] [Indexed: 10/22/2022]
Abstract
One-dimensional (1D) nanostructures have been regarded as the most promising building blocks for nanoelectronics and nanocomposite material systems as well as for alternative energy applications. Although they result in confinement of a material, their properties and interactions with other nanostructures are still very much three-dimensional (3D) in nature. In this work, we present a novel method for quantitative determination of the 3D electromagnetic fields in and around 1D nanostructures using a single electron wave phase image, thereby eliminating the cumbersome acquisition of tomographic data. Using symmetry arguments, we have reconstructed the 3D magnetic field of a nickel nanowire as well as the 3D electric field around a carbon nanotube field emitter, from one single projection. The accuracy of quantitative values determined here is shown to be a better fit to the physics at play than the value obtained by conventional analysis. Moreover the 3D reconstructions can then directly be visualized and used in the design of functional 3D architectures built using 1D nanostructures.
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Affiliation(s)
- C Phatak
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA.
| | - L de Knoop
- CEMES-CNRS, 29 rue Jeanne Marvig, F-31055 Toulouse, France; Université Paul Sabatier, F-31000 Toulouse, France
| | - F Houdellier
- CEMES-CNRS, 29 rue Jeanne Marvig, F-31055 Toulouse, France; Université Paul Sabatier, F-31000 Toulouse, France
| | - C Gatel
- CEMES-CNRS, 29 rue Jeanne Marvig, F-31055 Toulouse, France; Université Paul Sabatier, F-31000 Toulouse, France
| | - M J Hÿtch
- CEMES-CNRS, 29 rue Jeanne Marvig, F-31055 Toulouse, France
| | - A Masseboeuf
- CEMES-CNRS, 29 rue Jeanne Marvig, F-31055 Toulouse, France
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24
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Reyes D, Biziere N, Warot-Fonrose B, Wade T, Gatel C. Magnetic Configurations in Co/Cu Multilayered Nanowires: Evidence of Structural and Magnetic Interplay. NANO LETTERS 2016; 16:1230-1236. [PMID: 26783831 DOI: 10.1021/acs.nanolett.5b04553] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Off-axis electron holography experiments have been combined with micromagnetic simulations to study the remnant magnetic states of electrodeposited Co/Cu multilayered nanocylinders. Structural and chemical data obtained by transmission electron microscopy have been introduced in the simulations. Three different magnetic configurations such as an antiparallel coupling of the Co layers, coupled vortices, and a monodomain-like state have been quantitatively mapped and simulated. While most of the wires present the same remnant state whatever the direction of the saturation field, we show that some layers can present a change from an antiparallel coupling to vortices. Such a configuration can be of particular interest to design nano-oscillators with two different working frequencies.
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Affiliation(s)
- D Reyes
- CEMES CNRS-UPR 8011, Université de Toulouse , 31055 Toulouse, France
| | - N Biziere
- CEMES CNRS-UPR 8011, Université de Toulouse , 31055 Toulouse, France
| | - B Warot-Fonrose
- CEMES CNRS-UPR 8011, Université de Toulouse , 31055 Toulouse, France
| | - T Wade
- Laboratoire des Solides Irradiés, Ecole Polytechnique, CNRS, CEA, Université Paris Saclay , F 91128 Palaiseau, France
| | - C Gatel
- CEMES CNRS-UPR 8011, Université de Toulouse , 31055 Toulouse, France
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25
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Simon P, Wolf D, Wang C, Levin AA, Lubk A, Sturm S, Lichte H, Fecher GH, Felser C. Synthesis and Three-Dimensional Magnetic Field Mapping of Co2FeGa Heusler Nanowires at 5 nm Resolution. NANO LETTERS 2016; 16:114-120. [PMID: 26674206 DOI: 10.1021/acs.nanolett.5b03102] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present the synthesis of Co2FeGa Heusler nanowires and the results of our investigations on their three-dimensional (3D) electric and magnetic internal and external fields mapped by electron holographic tomography (EHT). These fields will be of great importance in next-generation nanomagnets integrated in spintronics and memory devices. The Co2FeGa nanowires with a L21 ordered structure are prepared by a SBA-15 silica-assisted method. The magnetic dipole-like stray fields of several Co2FeGa nanowires are revealed by holographically reconstructed phase images. Based on the measured magnetic phase shifts of an individual nanowire and its 3D reconstruction using EHT, we obtain an internal magnetic induction with a magnitude of 1.15 T and a nonmagnetic surface layer of 10 nm thickness. Furthermore, we also reconstruct the 3D distribution of the electrostatic potential of the same nanowire.
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Affiliation(s)
- Paul Simon
- Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - Daniel Wolf
- Institute of Structure Physics, Triebenberg Laboratory, Technical University of Dresden , Zum Triebenberg 50, 01328 Dresden Zaschendorf, Germany
| | - Changhai Wang
- Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - Aleksandr A Levin
- Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - Axel Lubk
- Institute of Structure Physics, Triebenberg Laboratory, Technical University of Dresden , Zum Triebenberg 50, 01328 Dresden Zaschendorf, Germany
| | - Sebastian Sturm
- Institute of Structure Physics, Triebenberg Laboratory, Technical University of Dresden , Zum Triebenberg 50, 01328 Dresden Zaschendorf, Germany
| | - Hannes Lichte
- Institute of Structure Physics, Triebenberg Laboratory, Technical University of Dresden , Zum Triebenberg 50, 01328 Dresden Zaschendorf, Germany
| | - Gerhard H Fecher
- Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - Claudia Felser
- Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Str. 40, 01187 Dresden, Germany
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26
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Peddis D, Muscas G, Mathieu R, Kumar PA, Varvaro G, Singh G, Orue I, Gil-Carton D, Marcano L, Muela A, Fdez-Gubieda ML. Studying nanoparticles’ 3D shape by aspect maps: Determination of the morphology of bacterial magnetic nanoparticles. Faraday Discuss 2016; 191:177-188. [DOI: 10.1039/c6fd00059b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Magnetic nanoparticles (MNPs) are widely investigated due to their potential use in various applications, ranging from electronics to biomedical devices. The magnetic properties of MNPs are strongly dependent on their size and shape (i.e., morphology), thus appropriate tools to investigate their morphology are fundamental to understand the physics of these systems. Recently a new approach to study nanoparticle morphology by Transmission Electron Microscopy (TEM) analysis has been proposed, introducing the so-called Aspect Maps (AMs). In this paper, a further evolution of the AM method is presented, allowing determination of the nanoparticles’ 3D shape by TEM image. As a case study, this paper will focus on magnetite nanoparticles (Fe3O4), with a mean size of ∼45 nm extracted from Magnetospirillum gryphiswaldense magnetostatic bacteria (MTB). The proposed approach gives a complete description of the nanoparticles’ morphology, allowing estimation of an average geometrical size and shape. In addition, preliminary investigation of the magnetic properties of MTB nanoparticles was performed, giving some insight into interparticle interactions and on the reversal mechanism of the magnetization.
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27
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Röder F, Hlawacek G, Wintz S, Hübner R, Bischoff L, Lichte H, Potzger K, Lindner J, Fassbender J, Bali R. Direct Depth- and Lateral- Imaging of Nanoscale Magnets Generated by Ion Impact. Sci Rep 2015; 5:16786. [PMID: 26584789 PMCID: PMC4653643 DOI: 10.1038/srep16786] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 10/20/2015] [Indexed: 11/09/2022] Open
Abstract
Nanomagnets form the building blocks for a variety of spin-transport, spin-wave and data storage devices. In this work we generated nanoscale magnets by exploiting the phenomenon of disorder-induced ferromagnetism; disorder was induced locally on a chemically ordered, initially non-ferromagnetic, Fe60Al40 precursor film using nm diameter beam of Ne(+) ions at 25 keV energy. The beam of energetic ions randomized the atomic arrangement locally, leading to the formation of ferromagnetism in the ion-affected regime. The interaction of a penetrating ion with host atoms is known to be spatially inhomogeneous, raising questions on the magnetic homogeneity of nanostructures caused by ion-induced collision cascades. Direct holographic observations of the flux-lines emergent from the disorder-induced magnetic nanostructures were made in order to measure the depth- and lateral- magnetization variation at ferromagnetic/non-ferromagnetic interfaces. Our results suggest that high-resolution nanomagnets of practically any desired 2-dimensional geometry can be directly written onto selected alloy thin films using a nano-focussed ion-beam stylus, thus enabling the rapid prototyping and testing of novel magnetization configurations for their magneto-coupling and spin-wave properties.
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Affiliation(s)
- Falk Röder
- Triebenberg Labor, Institut für Strukturphysik, Technische Universität Dresden, D-01062 Dresden, Germany
| | - Gregor Hlawacek
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany
| | - Sebastian Wintz
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany
| | - René Hübner
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany
| | - Lothar Bischoff
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany
| | - Hannes Lichte
- Triebenberg Labor, Institut für Strukturphysik, Technische Universität Dresden, D-01062 Dresden, Germany
| | - Kay Potzger
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany
| | - Jürgen Lindner
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany
| | - Jürgen Fassbender
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany.,Institut für Festkörperphysik, Technische Universität Dresden, Helmholtzstr. 10, D-01069 Dresden, Germany
| | - Rantej Bali
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany
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28
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Ercius P, Alaidi O, Rames MJ, Ren G. Electron Tomography: A Three-Dimensional Analytic Tool for Hard and Soft Materials Research. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:5638-63. [PMID: 26087941 PMCID: PMC4710474 DOI: 10.1002/adma.201501015] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 04/22/2015] [Indexed: 05/23/2023]
Abstract
Three-dimensional (3D) structural analysis is essential to understand the relationship between the structure and function of an object. Many analytical techniques, such as X-ray diffraction, neutron spectroscopy, and electron microscopy imaging, are used to provide structural information. Transmission electron microscopy (TEM), one of the most popular analytic tools, has been widely used for structural analysis in both physical and biological sciences for many decades, in which 3D objects are projected into two-dimensional (2D) images. In many cases, 2D-projection images are insufficient to understand the relationship between the 3D structure and the function of nanoscale objects. Electron tomography (ET) is a technique that retrieves 3D structural information from a tilt series of 2D projections, and is gradually becoming a mature technology with sub-nanometer resolution. Distinct methods to overcome sample-based limitations have been separately developed in both physical and biological science, although they share some basic concepts of ET. This review discusses the common basis for 3D characterization, and specifies difficulties and solutions regarding both hard and soft materials research. It is hoped that novel solutions based on current state-of-the-art techniques for advanced applications in hybrid matter systems can be motivated.
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Affiliation(s)
- Peter Ercius
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA
| | - Osama Alaidi
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA
| | - Matthew J. Rames
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA
| | - Gang Ren
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA
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29
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Cantu-Valle J, Betancourt I, Sanchez JE, Ruiz-Zepeda F, Maqableh MM, Mendoza-Santoyo F, Stadler BJH, Ponce A. Mapping the magnetic and crystal structure in cobalt nanowires. JOURNAL OF APPLIED PHYSICS 2015; 118:024302. [PMID: 26221057 PMCID: PMC4499055 DOI: 10.1063/1.4923745] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 06/23/2015] [Indexed: 06/05/2023]
Abstract
Using off-axis electron holography under Lorentz microscopy conditions to experimentally determine the magnetization distribution in individual cobalt (Co) nanowires, and scanning precession-electron diffraction to obtain their crystalline orientation phase map, allowed us to directly visualize with high accuracy the effect of crystallographic texture on the magnetization of nanowires. The influence of grain boundaries and disorientations on the magnetic structure is correlated on the basis of micromagnetic analysis in order to establish the detailed relationship between magnetic and crystalline structure. This approach demonstrates the applicability of the method employed and provides further understanding on the effect of crystalline structure on magnetic properties at the nanometric scale.
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Affiliation(s)
- Jesus Cantu-Valle
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle , San Antonio, Texas 78249, USA
| | - Israel Betancourt
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle , San Antonio, Texas 78249, USA
| | - John E Sanchez
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle , San Antonio, Texas 78249, USA
| | - Francisco Ruiz-Zepeda
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle , San Antonio, Texas 78249, USA
| | - Mazin M Maqableh
- Electrical and Computer Engineering, University of Minnesota , 4-174 EE/CSci Bldg., 200 Union St. SE, Minneapolis, Minnesota 55455, USA
| | - Fernando Mendoza-Santoyo
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle , San Antonio, Texas 78249, USA
| | - Bethanie J H Stadler
- Electrical and Computer Engineering, University of Minnesota , 4-174 EE/CSci Bldg., 200 Union St. SE, Minneapolis, Minnesota 55455, USA
| | - Arturo Ponce
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle , San Antonio, Texas 78249, USA
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31
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Körner M, Röder F, Lenz K, Fritzsche M, Lindner J, Lichte H, Fassbender J. Quantitative imaging of the magnetic configuration of modulated nanostructures by electron holography. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:5161-5169. [PMID: 25066641 DOI: 10.1002/smll.201400377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 06/30/2014] [Indexed: 06/03/2023]
Abstract
By means of off-axis electron holography the local distribution of the magnetic induction within and around a poly-crystalline Permalloy (Ni81Fe19) thin film is studied. In addition the stray field above the sample is measured by magnetic force microscopy on a larger area. The film is deposited on a periodically nanostructured (rippled) Si substrate, which was formed by Xe(+) ion beam erosion. This introduces the periodical ripple shape to the Permalloy film. The created ripple morphology is expected to modify the magnetization distribution within the Permalloy and to induce dipolar stray fields. These stray fields play an important role in spinwave dynamics of periodic nanostructures like magnonic crystals. Micromagnetic simulations estimate those stray fields in the order of only 10 mT. Consequently, their experimental determination at nanometer spatial resolution is highly demanding and requires advanced acquisition and reconstruction techniques such as electron holography. The reconstructed magnetic phase images show the magnetized thin film, in which the magnetization direction follows mainly the given morphology. Furthermore, a closer look to the Permalloy/carbon interface reveals stray fields at the detection limit of the method in the order of 10 mT, which is in qualitative agreement with the micromagnetic simulations.
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Affiliation(s)
- Michael Körner
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328, Dresden, Germany; Technische Universität Dresden, 01062, Dresden, Germany
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32
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Röder F, Lubk A, Wolf D, Niermann T. Noise estimation for off-axis electron holography. Ultramicroscopy 2014; 144:32-42. [PMID: 24821224 DOI: 10.1016/j.ultramic.2014.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 04/03/2014] [Accepted: 04/11/2014] [Indexed: 10/25/2022]
Abstract
Off-axis electron holography provides access to the phase of the elastically scattered wave in a transmission electron microscope at scales ranging from several hundreds of nanometres down to 0.1nm. In many cases the reconstructed phase shift is directly proportional to projected electric and magnetic potentials rendering electron holography a useful and established characterisation method for materials science. However, quantitative interpretation of experimental phase shifts requires quantitative knowledge about the noise, which has been previously established for some limiting cases only. Here, we present a general noise transfer formalism for off-axis electron holography allowing to compute the covariance (noise) of reconstructed amplitude and phase from characteristic detector functions and general properties of the reconstruction process. Experimentally, we verify the presented noise transfer formulas for two different cameras with and without objects within the errors given by the experimental noise determination.
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Affiliation(s)
- Falk Röder
- Triebenberg Labor, Institut für Strukturphysik, Technische Universität Dresden, D-01062 Dresden, Germany.
| | - Axel Lubk
- Triebenberg Labor, Institut für Strukturphysik, Technische Universität Dresden, D-01062 Dresden, Germany
| | - Daniel Wolf
- Triebenberg Labor, Institut für Strukturphysik, Technische Universität Dresden, D-01062 Dresden, Germany
| | - Tore Niermann
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
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Rodríguez LA, Magén C, Snoeck E, Gatel C, Marín L, Serrano-Ramón L, Prieto JL, Muñoz M, Algarabel PA, Morellon L, De Teresa JM, Ibarra MR. Quantitative in situ magnetization reversal studies in Lorentz microscopy and electron holography. Ultramicroscopy 2013; 134:144-54. [PMID: 23831132 DOI: 10.1016/j.ultramic.2013.06.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 06/05/2013] [Accepted: 06/07/2013] [Indexed: 10/26/2022]
Abstract
A generalized procedure for the in situ application of magnetic fields by means of the excitation of the objective lens for magnetic imaging experiments in Lorentz microscopy and electron holography is quantitatively described. A protocol for applying magnetic fields with arbitrary in-plane magnitude and orientation is presented, and a freeware script for Digital Micrograph(™) is provided to assist the operation of the microscope. Moreover, a method to accurately reconstruct hysteresis loops is detailed. We show that the out-of-plane component of the magnetic field cannot be always neglected when performing quantitative measurements of the local magnetization. Several examples are shown to demonstrate the accuracy and functionality of the methods.
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Affiliation(s)
- L A Rodríguez
- Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, 50018 Zaragoza, Spain; Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain; Transpyrenean Associated Laboratory for Electron Microscopy (TALEM), CEMES-INA, CNRS-Universidad de Zaragoza, Toulouse, France; CEMES-CNRS 29, rue Jeanne Marvig, B.P. 94347, F-31055 Toulouse Cedex, France
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Varón M, Beleggia M, Kasama T, Harrison RJ, Dunin-Borkowski RE, Puntes VF, Frandsen C. Dipolar magnetism in ordered and disordered low-dimensional nanoparticle assemblies. Sci Rep 2013; 3:1234. [PMID: 23390584 PMCID: PMC3565170 DOI: 10.1038/srep01234] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 01/18/2013] [Indexed: 11/14/2022] Open
Abstract
Magnetostatic (dipolar) interactions between nanoparticles promise to open new ways to design nanocrystalline magnetic materials and devices if the collective magnetic properties can be controlled at the nanoparticle level. Magnetic dipolar interactions are sufficiently strong to sustain magnetic order at ambient temperature in assemblies of closely-spaced nanoparticles with magnetic moments of ≥ 100 μB. Here we use electron holography with sub-particle resolution to reveal the correlation between particle arrangement and magnetic order in self-assembled 1D and quasi-2D arrangements of 15 nm cobalt nanoparticles. In the initial states, we observe dipolar ferromagnetism, antiferromagnetism and local flux closure, depending on the particle arrangement. Surprisingly, after magnetic saturation, measurements and numerical simulations show that overall ferromagnetic order exists in the present nanoparticle assemblies even when their arrangement is completely disordered. Such direct quantification of the correlation between topological and magnetic order is essential for the technological exploitation of magnetic quasi-2D nanoparticle assemblies.
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Affiliation(s)
- M Varón
- Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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37
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Kalirai SS, Bazylinski DA, Hitchcock AP. Anomalous magnetic orientations of magnetosome chains in a magnetotactic bacterium: Magnetovibrio blakemorei strain MV-1. PLoS One 2013; 8:e53368. [PMID: 23308202 PMCID: PMC3540082 DOI: 10.1371/journal.pone.0053368] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 11/30/2012] [Indexed: 11/19/2022] Open
Abstract
There is a good deal of published evidence that indicates that all magnetosomes within a single cell of a magnetotactic bacterium are magnetically oriented in the same direction so that they form a single magnetic dipole believed to assist navigation of the cell to optimal environments for their growth and survival. Some cells of the cultured magnetotactic bacterium Magnetovibrio blakemorei strain MV-1 are known to have relatively wide gaps between groups of magnetosomes that do not seem to interfere with the larger, overall linear arrangement of the magnetosomes along the long axis of the cell. We determined the magnetic orientation of the magnetosomes in individual cells of this bacterium using Fe 2p X-ray magnetic circular dichroism (XMCD) spectra measured with scanning transmission X-ray microscopy (STXM). We observed a significant number of cases in which there are sub-chains in a single cell, with spatial gaps between them, in which one or more sub-chains are magnetically polarized opposite to other sub-chains in the same cell. These occur with an estimated frequency of 4.0±0.2%, based on a sample size of 150 cells. We propose possible explanations for these anomalous cases which shed insight into the mechanisms of chain formation and magnetic alignment.
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Affiliation(s)
- Samanbir S. Kalirai
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
| | - Dennis A. Bazylinski
- School of Life Sciences, University of Nevada at Las Vegas, Las Vegas, Nevada, United States of America
| | - Adam P. Hitchcock
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
- * E-mail:
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Lartigue L, Hugounenq P, Alloyeau D, Clarke SP, Lévy M, Bacri JC, Bazzi R, Brougham DF, Wilhelm C, Gazeau F. Cooperative organization in iron oxide multi-core nanoparticles potentiates their efficiency as heating mediators and MRI contrast agents. ACS NANO 2012; 6:10935-49. [PMID: 23167525 DOI: 10.1021/nn304477s] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In the pursuit of optimized magnetic nanostructures for diagnostic and therapeutic applications, the role of nanoparticle architecture has been poorly investigated. In this study, we demonstrate that the internal collective organization of multi-core iron oxide nanoparticles can modulate their magnetic properties in such a way as to critically enhance their hyperthermic efficiency and their MRI T(1) and T(2) contrast effect. Multi-core nanoparticles composed of maghemite cores were synthesized through a polyol approach, and subsequent electrostatic colloidal sorting was used to fractionate the suspensions by size and hence magnetic properties. We obtained stable suspensions of citrate-stabilized nanostructures ranging from single-core 10 nm nanoparticles to multi-core magnetically cooperative 30 nm nanoparticles. Three-dimensional oriented attachment of primary cores results in enhanced magnetic susceptibility and decreased surface disorder compared to individual cores, while preserving a superparamagnetic-like behavior of the multi-core structures and potentiating thermal losses. Exchange coupling in the multi-core nanoparticles modifies the dynamics of the magnetic moment in such a way that both the longitudinal and transverse NMR relaxivities are also enhanced. Long-term MRI detection of tumor cells and their efficient destruction by magnetic hyperthermia can be achieved thanks to a facile and nontoxic cell uptake of these iron oxide nanostructures. This study proves for the first time that cooperative magnetic behavior within highly crystalline iron oxide superparamagnetic multi-core nanoparticles can improve simultaneously therapeutic and diagnosis effectiveness over existing nanostructures, while preserving biocompatibility.
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Affiliation(s)
- Lénaic Lartigue
- Laboratoire Matières et Systèmes Complexes, UMR 7057 CNRS/ Université Paris Diderot, 10 rue Alice Domon et Léonie Duquet, 75013 Paris, France
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39
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Masseboeuf A, Fruchart O, Cheynis F, Rougemaille N, Toussaint JC, Marty A, Bayle-Guillemaud P. Micromagnetic study of flux-closure states in Fe dots using quantitative Lorentz microscopy. Ultramicroscopy 2012; 115:26-34. [PMID: 22459115 DOI: 10.1016/j.ultramic.2012.02.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 02/06/2012] [Accepted: 02/11/2012] [Indexed: 11/26/2022]
Abstract
A micromagnetic study of epitaxial micron-sized iron dots is reported through the analysis of Fresnel contrast in Lorentz Microscopy. Their use is reviewed and developed through analysis of various magnetic structures in such dots. Simple Landau configuration is used to investigate various aspects of asymmetric Bloch domain walls. The experimental width of such a complex wall is first derived and its value is discussed with the help of micromagnetic simulations. Combination of these two approaches enables us to define what is really extracted when estimating asymmetric wall width in Lorentz Microscopy. Moreover, quantitative data on the magnetization inside the dot is retrieved using phase retrieval as well as new information on the degrees of freedom of such walls. Finally, it is shown how the existence and the propagation of a surface vortex can be characterized and monitored. This demonstrates the ability to reach a magnetic sensitivity a priori hidden in Fresnel contrast, based on an original image treatment and backed-up by the evaluation of contrasts obtained from micromagnetic simulations.
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Koziol KK, Kasama T, Dunin-Borkowski RE, Barpanda P, Windle AH. Electron Holography of Ferromagnetic Nanoparticles Encapsulated in Three-Dimensional Arrays of Aligned Carbon Nanotubes. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-0962-p13-03] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTClosely-spaced ferromagnetic nanoparticles are of interest for applications that include data storage, magnetic imaging and drug delivery. Here, we use off-axis electron holography and micromagnetic simulations to study the magnetic properties of iron nanoparticles encapsulated in three-dimensional arrays of carbon nanotubes. The nanotubes constrain the shapes, sizes and separations of the nanoparticles, as well protecting them from oxidation. We record magnetic induction maps from individual particles that each contain a single magnetic domain. We also discuss the use of electron holography to assess magnetostatic interactions between adjacent particles.
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41
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Wei A, Kasama T, Dunin-Borkowski RE. Self-assembly and flux closure studies of magnetic nanoparticle rings. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm11916h] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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42
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McNeil RPG, Schneble RJ, Kataoka M, Ford CJB, Kasama T, Dunin-Borkowski RE, Feinberg JM, Harrison RJ, Barnes CHW, Tse DHY, Trypiniotis T, Bland JAC, Anderson D, Jones GAC, Pepper M. Localized magnetic fields in arbitrary directions using patterned nanomagnets. NANO LETTERS 2010; 10:1549-1553. [PMID: 20377235 DOI: 10.1021/nl902949v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Control of the local magnetic fields desirable for spintronics and quantum information technology is not well developed. Existing methods produce either moderately small local fields or one field orientation. We present designs of patterned magnetic elements that produce remanent fields of 50 mT (potentially 200 mT) confined to chosen, submicrometer regions in directions perpendicular to an external initializing field. A wide variety of magnetic-field profiles on nanometer scales can be produced with the option of applying electric fields, for example, to move a quantum dot between regions where the magnetic-field direction or strength is different. We have confirmed our modeling by measuring the fields in one design using electron holography.
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Mørup S, Hansen MF, Frandsen C. Magnetic interactions between nanoparticles. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2010; 1:182-90. [PMID: 21977409 PMCID: PMC3045912 DOI: 10.3762/bjnano.1.22] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 12/03/2010] [Indexed: 05/17/2023]
Abstract
We present a short overview of the influence of inter-particle interactions on the properties of magnetic nanoparticles. Strong magnetic dipole interactions between ferromagnetic or ferrimagnetic particles, that would be superparamagnetic if isolated, can result in a collective state of nanoparticles. This collective state has many similarities to spin-glasses. In samples of aggregated magnetic nanoparticles, exchange interactions are often important and this can also lead to a strong suppression of superparamagnetic relaxation. The temperature dependence of the order parameter in samples of strongly interacting hematite nanoparticles or goethite grains is well described by a simple mean field model. Exchange interactions between nanoparticles with different orientations of the easy axes can also result in a rotation of the sub-lattice magnetization directions.
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Affiliation(s)
- Steen Mørup
- Department of Physics, Building 307; Technical University of Denmark; DK-2800 Kongens Lyngby; Denmark
| | - Mikkel Fougt Hansen
- Department of Micro- and Nanotechnology, DTU Nanotech, Building 345 East; Technical University of Denmark; DK-2800 Kongens Lyngby; Denmark
| | - Cathrine Frandsen
- Department of Physics, Building 307; Technical University of Denmark; DK-2800 Kongens Lyngby; Denmark
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Lichte H, Geiger D, Linck M. Off-axis electron holography in an aberration-corrected transmission electron microscope. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:3773-3793. [PMID: 19687065 DOI: 10.1098/rsta.2009.0126] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Electron holography allows the reconstruction of the complete electron wave, and hence offers the possibility of correcting aberrations. In fact, this was shown by means of the uncorrected CM30 Special Tübingen transmission electron microscope (TEM), revealing, after numerical aberration correction, a resolution of approximately 0.1 nm, both in amplitude and phase. However, it turned out that the results suffer from a comparably poor signal-to-noise ratio. The reason is that the limited coherent electron current, given by gun brightness, has to illuminate a width of at least four times the point-spread function given by the aberrations. As, using the hardware corrector, the point-spread function shrinks considerably, the current density increases and the signal-to-noise ratio improves correspondingly. Furthermore, the phase shift at the atomic dimensions found in the image plane also increases because the collection efficiency of the optics increases with resolution. In total, the signals of atomically fine structures are better defined for quantitative evaluation. In fact, the results achieved by electron holography in a Tecnai F20 Cs-corr TEM confirm this.
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Affiliation(s)
- Hannes Lichte
- Triebenberg Laboratory, Institute of Structure Physics, Technische Universität Dresden, Germany.
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Masseboeuf A, Gatel C, Bayle-Guillemaud P, Marty A, Toussaint JC. Lorentz microscopy mapping for domain wall structure study in L1(0) FePd thin films. Ultramicroscopy 2009; 110:20-5. [PMID: 19766396 DOI: 10.1016/j.ultramic.2009.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 08/19/2009] [Accepted: 08/26/2009] [Indexed: 10/20/2022]
Abstract
Thin film alloys with perpendicular anisotropy were studied using Lorentz transmission electron microscopy (LTEM). This work focuses on the configuration of domain walls and demonstrates the suitability and accuracy of LTEM for the magnetic characterization of perpendicular magnetic anisotropy materials. Thin films of chemically ordered (L1(0)) FePd alloys were investigated by micro-magnetic modeling and LTEM phase retrieval approach. The different components of magnetization described by the modeling were studied on experimental images and confirmed by LTEM contrast simulation. Furthermore, quantitative measurements of magnetic induction inside the domain walls were made by using an original method to separate the electrical and magnetical contributions to the phase information. Irregularities were also observed along the domain walls which could play a major role during the magnetization processes.
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Affiliation(s)
- Aurélien Masseboeuf
- CEA, INAC-SP2M, Laboratoire d'Etude des Matériaux et des Microscopies Avancées 17 rue des Martyrs, 38054 Grenoble Cedex 09, France.
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46
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Masseboeuf A, Marty A, Bayle-Guillemaud P, Gatel C, Snoeck E. Quantitative observation of magnetic flux distribution in new magnetic films for future high density recording media. NANO LETTERS 2009; 9:2803-2806. [PMID: 19572734 DOI: 10.1021/nl900800q] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Off-axis electron holography was used to observe and quantify the magnetic microstructure of a perpendicular magnetic anisotropic (PMA) recording media. Thin foils of PMA materials exhibit an interesting up and down domain configuration. These domains are found to be very stable and were observed at the same time with their stray field, closing magnetic flux in the vacuum. The magnetic moment can thus be determined locally in a volume as small as few tens of cubic nanometers().
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Affiliation(s)
- Aurélien Masseboeuf
- CEA, Institut Nanosciences et Cryogénie - SP2M, 17 rue des Martyrs, 38054 Grenoble Cedex 09, France
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Midgley PA, Dunin-Borkowski RE. Electron tomography and holography in materials science. NATURE MATERIALS 2009; 8:271-80. [PMID: 19308086 DOI: 10.1038/nmat2406] [Citation(s) in RCA: 393] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The rapid development of electron tomography, in particular the introduction of novel tomographic imaging modes, has led to the visualization and analysis of three-dimensional structural and chemical information from materials at the nanometre level. In addition, the phase information revealed in electron holograms allows electrostatic and magnetic potentials to be mapped quantitatively with high spatial resolution and, when combined with tomography, in three dimensions. Here we present an overview of the techniques of electron tomography and electron holography and demonstrate their capabilities with the aid of case studies that span materials science and the interface between the physical sciences and the life sciences.
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Affiliation(s)
- Paul A Midgley
- Department of Materials Science & Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK.
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48
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Thomas JM, Simpson ET, Kasama T, Dunin-Borkowski RE. Electron holography for the study of magnetic nanomaterials. Acc Chem Res 2008; 41:665-74. [PMID: 18459804 DOI: 10.1021/ar700225v] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Transmission electron microscopes fitted with field-emission guns (to provide coherent electron waves) can be adapted to record the magnetic fields within and surrounding nanoparticles or metal clusters, for example, the lines of force of a nanoferromagnet encapsulated within a multiwalled carbon nanotube. Whereas most chemists are aware that electron microscopy readily identifies crystallographic symmetries and phases, solves structures, and, in conjunction with electron energy-loss spectroscopy, yields valence states and electronic information of materials, relatively few know that it can also provide important quantitative information, with nanometer-scale spatial resolution, pertaining to such materials' magnetic properties. In this Account, with the aid of representative examples embracing solid-state chemistry, geochemistry, and bio-inorganic phenomena, we illustrate how off-axis electron holography affords deep insight into magnetic phenomena on the nanoscale. Specifically, we describe the unprecedented level of information available regarding the magnetic nature of magnetotactic bacteria, magnetic nanoparticle chains and chiral bracelets, and geochemically relevant phenomena involving exsolution (the un-mixing of two mineral phases, as in the magnetite-ulvöspinel system). It is, for example, possible to reveal vortices and multidomain states that have no net magnetization in minute blocks of magnetite. With the current burgeoning interest and activity in nanoscience and nanotechnology, our Account concludes with examples of some existing enigmas that electron holography, especially when augmented by the related technique of electron tomography, might play an important experimental role in resolving, such as the occurrence of ferromagnetism in nanocrystals of silver within carbon tubes and in clusters of alkali metals incarcerated within zeolites.
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Affiliation(s)
- John Meurig Thomas
- Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, U.K.,
| | - Edward T. Simpson
- Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, U.K.,
| | - Takeshi Kasama
- Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, U.K.,
| | - Rafal E. Dunin-Borkowski
- Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, U.K.,
- Center for Electron Nanoscopy, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
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Schattschneider P, Verbeeck J. Fringe contrast in inelastic LACBED holography. Ultramicroscopy 2008; 108:407-14. [PMID: 17656020 DOI: 10.1016/j.ultramic.2007.05.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 05/15/2007] [Accepted: 05/25/2007] [Indexed: 10/23/2022]
Abstract
We discuss diffraction holography in a scattering geometry reported by Herring [Ultramicroscopy 104 (2005) 261, Ultramicroscopy 106 (2006) 960] and interpreted in terms of the density matrix of the fast electrons. Whereas the previous description used an approximation replacing the LACBED by a CBED geometry and consequently left some doubts about the conclusions (namely the non-detectability of the MDFF) we now fully include the Fresnel propagator and the biprism operator in order to calculate the density matrix of the inelastically scattered electrons in LACBED geometry. We show that a defocus on the biprism with respect to the sample does not cause a significant effect on the fringe patterns that are formed when the discs are exactly overlapping. An important difference to the CBED geometry is however that the fringe contrast decreases when the shear deviates from a reciprocal lattice vector. This should enable to measure the spatial coherence for smaller shears than is possible in image holography.
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Jourdain V, Simpson ET, Paillet M, Kasama T, Dunin-Borkowski RE, Poncharal P, Zahab A, Loiseau A, Robertson J, Bernier P. Periodic Inclusion of Room-Temperature-Ferromagnetic Metal Phosphide Nanoparticles in Carbon Nanotubes. J Phys Chem B 2006; 110:9759-63. [PMID: 16706422 DOI: 10.1021/jp061181f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We demonstrate the use of sequential catalytic growth to encapsulate iron, nickel-iron, and iron-cobalt phosphide catalyst nanoparticles periodically along the entire lengths of carbon nanotubes. Investigations by local electron spectroscopies and electron diffraction reveal the compositions and crystal structures of the encapsulated particles. Significantly, high spatial resolution magnetic characterization using magnetic force microscopy and off-axis electron holography demonstrates that encapsulated iron-cobalt phosphide nanoparticles are ferromagnetic at room temperature, in accordance with the properties of bulk metal phosphides of the same structure and composition.
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