101 results on '"Damien McGrouther"'
Search Results
2. Synthetic ferrimagnet nanowires with very low critical current density for coupled domain wall motion
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Serban Lepadatu, Henri Saarikoski, Robert Beacham, Maria Jose Benitez, Thomas A. Moore, Gavin Burnell, Satoshi Sugimoto, Daniel Yesudas, May C. Wheeler, Jorge Miguel, Sarnjeet S. Dhesi, Damien McGrouther, Stephen McVitie, Gen Tatara, and Christopher H. Marrows
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Medicine ,Science - Abstract
Abstract Domain walls in ferromagnetic nanowires are potential building-blocks of future technologies such as racetrack memories, in which data encoded in the domain walls are transported using spin-polarised currents. However, the development of energy-efficient devices has been hampered by the high current densities needed to initiate domain wall motion. We show here that a remarkable reduction in the critical current density can be achieved for in-plane magnetised coupled domain walls in CoFe/Ru/CoFe synthetic ferrimagnet tracks. The antiferromagnetic exchange coupling between the layers leads to simple Néel wall structures, imaged using photoemission electron and Lorentz transmission electron microscopy, with a width of only ~100 nm. The measured critical current density to set these walls in motion, detected using magnetotransport measurements, is 1.0 × 1011 Am−2, almost an order of magnitude lower than in a ferromagnetically coupled control sample. Theoretical modelling indicates that this is due to nonadiabatic driving of anisotropically coupled walls, a mechanism that can be used to design efficient domain-wall devices.
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- 2017
- Full Text
- View/download PDF
3. Imaging and controlling plasmonic interference fields at buried interfaces
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Tom T. A. Lummen, Raymond J. Lamb, Gabriele Berruto, Thomas LaGrange, Luca Dal Negro, F. Javier García de Abajo, Damien McGrouther, B. Barwick, and F. Carbone
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Science - Abstract
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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- 2016
- Full Text
- View/download PDF
4. Magnetic scanning gate microscopy of CoFeB lateral spin valve
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Héctor Corte-León, Alexander Fernandez Scarioni, Rhodri Mansell, Patryk Krzysteczko, David Cox, Damien McGrouther, Stephen McVitie, Russell Cowburn, Hans W. Schumacher, Vladimir Antonov, and Olga Kazakova
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Physics ,QC1-999 - Abstract
Devices comprised of CoFeB nanostructures with perpendicular magnetic anisotropy and non-magnetic Ta channel were operated in thermal lateral spin valve (LSV) mode and studied by magnetotransport measurements and magnetic scanning gate microscopy (SGM). Due to the short spin diffusion length of Ta, the spin diffusion signal was suppressed, allowing the study of the contribution from the anomalous Nernst (ANE) and anomalous Hall effects (AHE). The magnetotransport measurements identified the switching fields of the CoFeB nanostructures and demonstrated a combination of AHE and ANE when the devices were operated in thermally-driven spin-injection mode. Modified scanning probe microscopy probes were fabricated by placing a NdFeB magnetic bead (MB) on the apex of a commercial Si probe. The dipole magnetic field distribution around the MB was characterized by using differential phase contrast technique and direct measurement of the switching field induced by the bead in the CoFeB nanodevices. Using SGM we demonstrate the influence of localized magnetic field on the CoFeB nanostructures near the non-magnetic channel. This approach provides a promising route towards the study of thermal and spin diffusion effects using local magnetic fields.
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- 2017
- Full Text
- View/download PDF
5. Fast Pixelated Detectors in Scanning Transmission Electron Microscopy. Part I: Data Acquisition, Live Processing, and Storage
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Damien McGrouther, Kirsty A. Paton, Magnus Nord, Ian MacLaren, Gary W. Paterson, Stephen McVitie, and Robert W. H. Webster
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Physics - Instrumentation and Detectors ,Computer science ,FOS: Physical sciences ,Context (language use) ,02 engineering and technology ,01 natural sciences ,Data acquisition ,Software ,0103 physical sciences ,Scanning transmission electron microscopy ,Instrumentation ,QC ,010302 applied physics ,Condensed Matter - Materials Science ,business.industry ,Physics ,Detector ,Materials Science (cond-mat.mtrl-sci) ,Instrumentation and Detectors (physics.ins-det) ,Transparency (human–computer interaction) ,021001 nanoscience & nanotechnology ,File format ,Visualization ,Chemistry ,0210 nano-technology ,business ,Computer hardware - Abstract
The use of fast pixelated detectors and direct electron detection technology is revolutionising 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 visualisation, 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 is available under an open source licence, permitting transparency of the implemented algorithms, and allowing the community to freely use and further improve upon them., 16 pages, 7 figures, post revision
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- 2020
6. Spontaneous creation and annihilation dynamics and strain-limited stability of magnetic skyrmions
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Gary W. Paterson, Henk J. M. Swagten, Johannes W. van der Jagt, Damien McGrouther, R. J. Lamb, and Frederic Rendell-Bhatti
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Information storage ,Science ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,Imaging techniques ,01 natural sciences ,Stability (probability) ,General Biochemistry, Genetics and Molecular Biology ,Article ,Spin magnetic moment ,Topological defects ,Magnetic properties and materials ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,010306 general physics ,lcsh:Science ,Nonlinear Sciences::Pattern Formation and Solitons ,Topological quantum number ,Spin-½ ,Physics ,Condensed Matter::Quantum Gases ,Condensed Matter - Materials Science ,Multidisciplinary ,Annihilation ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Skyrmion ,Exchange interaction ,Dynamics (mechanics) ,High Energy Physics::Phenomenology ,Materials Science (cond-mat.mtrl-sci) ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,lcsh:Q ,0210 nano-technology - 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., 19 pages total. 4 figures at the end of the main text, supplementary material follows
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- 2020
7. Effect of annealing on the magnetic states of FEBID‐grown cobalt nanopatterns examined by off‐axis electron holography
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Stephen McVitie, Damien McGrouther, András Kovács, Trevor P. Almeida, and Rafal E. Dunin-Borkowski
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0303 health sciences ,Histology ,Materials science ,Magnetism ,Annealing (metallurgy) ,chemistry.chemical_element ,Nanoparticle ,02 engineering and technology ,equipment and supplies ,021001 nanoscience & nanotechnology ,Electron holography ,Pathology and Forensic Medicine ,law.invention ,03 medical and health sciences ,chemistry ,Transmission electron microscopy ,law ,Chemical physics ,Crystallite ,Electron microscope ,0210 nano-technology ,human activities ,Cobalt ,030304 developmental biology - Abstract
The growth of cobalt nanopatterns (NPs) using focused electron-beam induced deposition (FEBID) for localised magnetic studies is presented. The initial FEBID products are shown to be polycrystalline and form hetero-structured core-shell NPs through surface oxidation. Off-axis electron holography is performed to reconstruct their morphology, thickness profile and image their individual magnetic vortex domain states. In situ annealing to 400°C promoted migration of the Co-overspray to grow the Co NPs and improved their crystallinity through coarsening, as well as induced diffusion of embedded carbon out of their surface. It is found that the change in their morphology and chemical instability under heating restricts their suitability for examining thermally induced magnetic variations. LAY DESCRIPTION: In this paper, electron microscopy is used to deposit magnetic cobalt nanopatterns and characterise the effect of in-situ heating on their chemistry, structure and magnetic properties. The electron beam of the secondary electron microscope is used to dissociate an injected precursor gas near the SiN membrane substrate of in-situ transmission electron microscopy (TEM) chips and locally deposit the elemental Co in circular patterns ∼ 90 nm in diameter. TEM reveals formation of a Co-oxide shell and embedding of carbon from the precursor gas during growth. The technique of electron holography is used to image the magnetism of the core-shell Co / Co-oxide nanopatterns, which are shown to exhibit magnetic vortex states. In-situ annealing results in migration of the Co overspray to increase their height and carbon diffusion from their surface, as well as change in their original magnetic state through change of orientation. It is found that the change in the morphology and chemistry of Co nanopatterns under heating limits their use for studying the effect of temperature on their magnetism in isolation.
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- 2020
8. Atomic resolution HOLZ-STEM imaging of atom position modulation in oxide heterostructures
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Christopher S. Allen, Magnus Nord, Ian MacLaren, Damien McGrouther, Angus I. Kirkland, and Juri Barthel
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010302 applied physics ,Materials science ,Order (ring theory) ,Heterojunction ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Ring (chemistry) ,01 natural sciences ,Molecular physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Electron diffraction ,Position (vector) ,Modulation ,ddc:570 ,0103 physical sciences ,Atom ,0210 nano-technology ,Instrumentation ,Perovskite (structure) - 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 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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- 2021
9. Sputter-engineering a first-order magnetic phase transition in sub-15-nm-thick single-crystal FeRh films
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Trevor P. Almeida, Damien McGrouther, Stephen McVitie, L. Benito, Laura Clark, Christopher H. Marrows, and T. A. Moore
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Diffraction ,Phase transition ,Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Spintronics ,Alloy ,02 engineering and technology ,Surface finish ,engineering.material ,021001 nanoscience & nanotechnology ,01 natural sciences ,Sputtering ,0103 physical sciences ,engineering ,General Materials Science ,Specular reflection ,010306 general physics ,0210 nano-technology ,Single crystal - Abstract
Equiatomic FeRh alloys undergo a fascinating first-order metamagnetic phase transition (FOMPT) just above room temperature, which has attracted reinvigorated interest for applications in spintronics. Until now, all attempts to grow nanothin FeRh alloy films have consistently shown that FeRh layers tend to grow in the Volmer-Weber growth mode. Here we show that sputter-grown sub-15-nm-thick FeRh alloy films deposited at low sputter-gas pressure, typically ∼0.1 Pa, onto (001)-oriented MgO substrates, grow in a peening-induced Frank-van der Merwe growth mode for FeRh film thicknesses above 5 nm, circumventing this major drawback. The bombardment of high-energy sputtered atoms, the atom-peening effect, induces a rebalancing between adsorbate-surface and adsorbate-adsorbate interactions, leading to the formation of a smooth continuous nanothin FeRh film. Chemical order in the films increases with the FeRh thickness, tFeRh, and varies monotonically from 0.75 up to 0.9. Specular x-ray diffraction scans around Bragg peaks show Pendellösung fringes for films with tFeRh≥5.2 nm, which reflects in smooth well-ordered densified single-crystal FeRh layers. The nanothin film's roughness varies from 0.6 down to about 0.1 nm as tFeRh increases, and scales linearly with the integral breadth of the rocking curve, proving its microstructured origin. Magnetometry shows that the FOMPT in the nanothin films is qualitatively similar to that of the bulk alloy, except for the thinnest film of 3.7 nm.
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- 2020
10. A comparison of a direct electron detector and a high-speed video camera for a scanning precession electron diffraction phase and orientation mapping
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A. C. Robins, S. McFadzean, Doug Cosart, Eduardo Nebot del Busto, Damien McGrouther, J. Portillo, J. K. Weiss, Ian MacLaren, Stavros Nicolopoulos, Enrique Frutos-Myro, and Richard Skogeby
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010302 applied physics ,Diffraction ,Materials science ,Electron crystallography ,business.industry ,Detector ,Phase (waves) ,02 engineering and technology ,Electron ,Inelastic scattering ,021001 nanoscience & nanotechnology ,01 natural sciences ,Optics ,0103 physical sciences ,Precession ,Precession electron diffraction ,0210 nano-technology ,business ,Instrumentation - 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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- 2020
11. Fast Pixelated Detectors in Scanning Transmission Electron Microscopy. Part II: Post-Acquisition Data Processing, Visualization, and Structural Characterization
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Damien McGrouther, Kirsty A. Paton, Thomas A. Macgregor, Gary W. Paterson, Andrew Ross, Magnus Nord, Ian MacLaren, and Robert W. H. Webster
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Physics - Instrumentation and Detectors ,Materials science ,FOS: Physical sciences ,02 engineering and technology ,01 natural sciences ,Optics ,0103 physical sciences ,Scanning transmission electron microscopy ,Precession electron diffraction ,Instrumentation ,010302 applied physics ,Condensed Matter - Materials Science ,Data processing ,Pixel ,business.industry ,Physics ,Detector ,Materials Science (cond-mat.mtrl-sci) ,Instrumentation and Detectors (physics.ins-det) ,021001 nanoscience & nanotechnology ,Characterization (materials science) ,Visualization ,Chemistry ,Electron diffraction ,0210 nano-technology ,business - 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 visualisation 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 visualisation of such datasets. Throughout, we provide examples of the analysis methodologies presented, utilising data from a 256$\times$256 pixel Medipix3 hybrid DED detector, with a particular focus on the STEM characterisation 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 nanoscale lattice parameter mapping with a fractional precision $\le 6\times10^{-4}$ (0.06%)., 23 pages, 12 figures, add open data zenodo doi and revise precision discussion
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- 2020
12. Sub-100 nanosecond temporally resolved imaging with the Medipix3 direct electron detector
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Rafael Ballabriga, Dima Maneuski, Damien McGrouther, Val O'Shea, Gary W. Paterson, and R. J. Lamb
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Physics - Instrumentation and Detectors ,Materials science ,FOS: Physical sciences ,02 engineering and technology ,Electron ,01 natural sciences ,Optics ,0103 physical sciences ,Scanning transmission electron microscopy ,Detectors and Experimental Techniques ,Instrumentation ,physics.ins-det ,010302 applied physics ,Condensed Matter - Materials Science ,business.industry ,Detector ,Materials Science (cond-mat.mtrl-sci) ,Instrumentation and Detectors (physics.ins-det) ,Nanosecond ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,cond-mat.mtrl-sci ,3. Good health ,Electronic, Optical and Magnetic Materials ,Orders of magnitude (time) ,Temporal resolution ,Cathode ray ,Electrostatic deflection ,0210 nano-technology ,business - 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 60keV, 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 100ns. 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., Comment: 11 pages, 6 figures; improve ref formatting + revise text
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- 2020
13. Asymmetric Magnetic Relaxation behavior of Domains and Domain Walls Observed Through the FeRh First-Order Metamagnetic Phase Transition
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Nicolas A. Peters, R. J. Lamb, P. Steadman, R. P. Campion, Damien McGrouther, Trevor P. Almeida, Stephen McVitie, Rowan Temple, R. Fan, Jamie Massey, and Christopher H. Marrows
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Phase transition ,Phase boundary ,Materials science ,Condensed matter physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Magnetometer ,FOS: Physical sciences ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Isothermal process ,3. Good health ,law.invention ,Coupling (physics) ,Dynamic light scattering ,law ,Phase (matter) ,0103 physical sciences ,Domain (ring theory) ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,010306 general physics ,0210 nano-technology - Abstract
The phase coexistence present through a first-order phase transition means there will be finite regions between the two phases where the structure of the system will vary from one phase to the other, known as a phase boundary wall. This region is said to play an important but unknown role in the dynamics of the first-order phase transitions. Here, by using both x-ray photon correlation spectroscopy and magnetometry techniques to measure the temporal isothermal development at various points through the thermally activated first-order metamagnetic phase transition present in the near-equiatomic FeRh alloy, we are able to isolate the dynamic behavior of the domain walls in this system. These investigations reveal that relaxation behavior of the domain walls changes when phase coexistence is introduced into the system and that the domain wall dynamics is different to the macroscale behavior. We attribute this to the effect of the exchange coupling between regions of either magnetic phase changing the dynamic properties of domain walls relative to bulk regions of either phase. We also believe this behavior comes from the influence of the phase boundary wall on other magnetic objects in the system., Main Paper: 13 pages, 8 figures. Supplementary information: 13 pages, 8 figures
- Published
- 2019
14. Attosecond coherent control of free-electron wave functions using semi-infinite light fields
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Fabrizio Carbone, Enrico Pomarico, I. Madan, Giovanni Maria Vanacore, F. Javier García de Abajo, Brett Barwick, Ido Kaminer, Damien McGrouther, Kangpeng Wang, R. J. Lamb, Gabriele Berruto, Vanacore, G, Madan, I, Berruto, G, Wang, K, Pomarico, E, Lamb, R, Mcgrouther, D, Kaminer, I, Barwick, B, de Abajo, F, and Carbone, F
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Free electron model ,electron-light quantum interaction ,semi-infinite light field ,Wave packet ,Attosecond ,Science ,General Physics and Astronomy ,02 engineering and technology ,Electron ,electron wave function manipulation ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Article ,Photon-Induced Near-Field Electron Microscopy (PINEM) ,0103 physical sciences ,Author Correction ,010306 general physics ,Wave function ,lcsh:Science ,Physics ,Multidisciplinary ,coherent control of nuclear reactions with light-shaped ultrafast electrons ,Ultrafast Electron Energy-Loss Spectroscopy ,General Chemistry ,021001 nanoscience & nanotechnology ,energy-momentum space ,Ultrafast Electron Microscopy ,Coherent control ,Quantum electrodynamics ,lcsh:Q ,0210 nano-technology ,Ultrashort pulse ,Light field - Abstract
Light–electron interaction is the seminal ingredient in free-electron lasers and dynamical investigation of matter. Pushing the coherent control of electrons by light to the attosecond timescale and below would enable unprecedented applications in quantum circuits and exploration of electronic motions and nuclear phenomena. Here we demonstrate attosecond coherent manipulation of a free-electron wave function, and show that it can be pushed down to the zeptosecond regime. We make a relativistic single-electron wavepacket interact in free-space with a semi-infinite light field generated by two light pulses reflected from a mirror and delayed by fractions of the optical cycle. The amplitude and phase of the resulting electron–state coherent oscillations are mapped in energy-momentum space via momentum-resolved ultrafast electron spectroscopy. The experimental results are in full agreement with our analytical theory, which predicts access to the zeptosecond timescale by adopting semi-infinite X-ray pulses., Manipulation of the electron–photon coupling is crucial for quantum circuits and exploration of electronic motions and nuclear phenomena. Here the authors discuss a scheme to coherently control the electron wave function from attosecond to zeptosecond timescales by using semi-infinite light fields.
- Published
- 2018
15. Quantifying the performance of a hybrid pixel detector with GaAs:Cr sensor for transmission electron microscopy
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Christopher S. Allen, Val O'Shea, Kirsty A. Paton, Damien McGrouther, Christian Kübel, Xiaoke Mu, Matthew C. Veale, Dzmitry Maneuski, and Angus I. Kirkland
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Diffraction ,Technology ,Physics - Instrumentation and Detectors ,Materials science ,Physics::Instrumentation and Detectors ,FOS: Physical sciences ,02 engineering and technology ,Electron ,DQE ,Hybrid pixel detector ,01 natural sciences ,Detective quantum efficiency ,Optical transfer function ,0103 physical sciences ,Instrumentation ,010302 applied physics ,Condensed Matter - Materials Science ,Pixel ,Direct electron detector ,business.industry ,Detector ,Materials Science (cond-mat.mtrl-sci) ,Instrumentation and Detectors (physics.ins-det) ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,MTF ,Transmission electron microscopy ,Optoelectronics ,0210 nano-technology ,business ,ddc:600 ,Energy (signal processing) - 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 (MAPS) is that their sensor does not need to be fabricated from Si. We have compared the performance of the Medipix3 HPD with a Si sensor and with a GaAs:Cr sensor using primary electrons in the energy range of 60 - 300keV. 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., Comment: 15 pages + references, 13 figures
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- 2021
16. Transforming Transmission Electron Microscopy with MerlinEM Electron Counting Detector
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Jean-Denis Blazit, Christopher S. Allen, Damien McGrouther, Alexander Zintler, Marcel Tencé, Alexandre Gloter, Robert Eilhardt, Matus Krajnak, Doug Cosart, J. K. Weiss, and Leopoldo Molina-Luna
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Optics ,Materials science ,business.industry ,Transmission electron microscopy ,Detector ,business ,Electron counting ,Instrumentation - Published
- 2020
17. Ionenstrahlen erzeugen periodische, magnetische Domänenstrukturen
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Kay Potzger, Damien McGrouther, Rantej Bali, and Magnus Nord
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Materials science - Published
- 2020
18. Focused Electron-Beam Induced Deposition, In Situ TEM And Off-Axis Electron Holography Investigation of Bi-Magnetic Core-Shell Nanostructures
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Trevor P. Almeida, András Kovács, Rafal E. Dunin-Borkowski, Damien McGrouther, and Stephen McVitie
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In situ ,Materials science ,Nanostructure ,Magnetic core ,Shell (structure) ,Electron beam-induced deposition ,Instrumentation ,Molecular physics ,Electron holography ,QC - Abstract
No abstract available.
- Published
- 2019
19. Three-dimensional subnanoscale imaging of unit cell doubling due to octahedral tilting and cation modulation in strained perovskite thin films
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Juri Barthel, Ingrid Hallsteinsen, Thomas Tybell, Magnus Moreau, Damien McGrouther, Andrew Ross, Magnus Nord, and Ian MacLaren
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Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Octahedron ,Transmission electron microscopy ,Modulation ,0103 physical sciences ,Optoelectronics ,ddc:530 ,General Materials Science ,Thin film ,010306 general physics ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
Determining the three-dimensional (3D) crystallography of a material with subnanometer resolution is essential to understanding strain effects in epitaxial thin films. A scanning transmission electron microscopy imaging technique is demonstrated that visualizes the presence and strength of atomic movements leading to a period doubling of the unit cell along the beam direction, using the intensity in an extra Laue zone ring in the back focal plane recorded using a pixelated detector method. This method is used together with conventional atomic resolution imaging in the plane perpendicular to the beam direction to gain information about the 3D crystal structure in an epitaxial thin film of LaFeO3 sandwiched between a substrate of (111) SrTiO3 and a top layer of La0.7Sr0.3MnO3. It is found that a hitherto unreported structure of LaFeO3 is formed under the unusual combination of compressive strain and (111) growth, which is triclinic with a periodicity doubling from primitive perovskite along one of the three ⟨110⟩ directions lying in the growth plane. This results from a combination of La-site modulation along the beam direction, and modulation of oxygen positions resulting from octahedral tilting. This transition to the period-doubled cell is suppressed near both the substrate and near the La0.7Sr0.3MnO3 top layer due to the clamping of the octahedral tilting by the absence of tilting in the substrate and due to an incompatible tilt pattern being present in the La0.7Sr0.3MnO3 layer. This work shows a rapid and easy way of scanning for such transitions in thin films or other systems where disorder-order transitions or domain structures may be present and does not require the use of atomic resolution imaging, and could be done on any scanning transmission electron microscopy instrument equipped with a suitable camera.
- Published
- 2019
20. Ultrafast generation and control of an electron vortex beam via chiral plasmonic near fields
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Damien McGrouther, Giovanni Maria Vanacore, Ori Reinhardt, Paolo Biagioni, I. Madan, Vincenzo Grillo, Gabriele Berruto, Ido Kaminer, Brett Barwick, Enrico Pomarico, Fabrizio Carbone, R. J. Lamb, Hugo Larocque, Ebrahim Karimi, F. J. García de Abajo, Vanacore, G, Berruto, G, Madan, I, Pomarico, E, Biagioni, P, Lamb, R, Mcgrouther, D, Reinhardt, O, Kaminer, I, Barwick, B, Larocque, H, Grillo, V, Karimi, E, Garcia de Abajo, F, and Carbone, F
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Attosecond ,FOS: Physical sciences ,02 engineering and technology ,Electron ,010402 general chemistry ,7. Clean energy ,01 natural sciences ,Molecular physics ,General Materials Science ,Plasmon ,Physics ,Quantum Physics ,electron microscopy ,Mechanical Engineering ,Ultrafast Electron Microscopy, Vortex Electrons, Chiral Plasmons, Coherent Control, Electron Dichroism ,General Chemistry ,Vorticity ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Vortex ,Mechanics of Materials ,Coherent control ,Femtosecond ,Quantum Physics (quant-ph) ,0210 nano-technology ,Ultrashort pulse ,Optics (physics.optics) ,Physics - Optics - 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 wave function. 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 wave function of charged composite particles, such as protons, and how it can be used to probe their internal structure., 14 pages, 4 figures
- Published
- 2019
21. Direct visualization of the magnetostructural phase transition in nano-scale FeRh thin films using differential phase contrast imaging
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Rowan Temple, Yue Li, Damien McGrouther, Stephen McVitie, T. A. Moore, Jamie Massey, Christopher H. Marrows, and Trevor P. Almeida
- Subjects
Phase transition ,Condensed Matter - Materials Science ,Materials science ,Physics and Astronomy (miscellaneous) ,Spintronics ,business.industry ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,02 engineering and technology ,Substrate (electronics) ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferromagnetism ,Phase (matter) ,0103 physical sciences ,Optoelectronics ,Antiferromagnetism ,General Materials Science ,Thin film ,010306 general physics ,0210 nano-technology ,business ,Nanoscopic scale - Abstract
To advance the use of thermally-activated magnetic materials in device applications it is necessary to examine their behaviour on the localised scale in operando conditions. Equi-atomic FeRh undergoes a magnetostructural transition from an antiferromagnetic (AF) to a ferromagnetic (FM) phase above room temperature (~ 75 to 105 {\deg}C) and hence is considered a very desirable material for the next generation of novel nanomagnetic or spintronic devices. For this to be realised, we must fully understand the intricate details of AF to FM transition and associated FM domain growth on the scale of their operation. Here we combine in-situ heating with a comprehensive suite of advanced transmission electron microscopy techniques to investigate directly the magnetostructural transition in nano-scale FeRh thin films. Differential phase contrast imaging visualizes the stages of FM domain growth in both cross-sectional and planar FeRh thin films as a function of temperature. Small surface FM signals are also detected due to interfacial strain with the MgO substrate and Fe deficiency after HF etching of the substrate, providing a directional bias for FM domain growth. Our work provides high resolution imaging and quantitative measurements throughout the transition, which were previously inaccessible, and offers new fundamental insight into their potential use in magnetic devices.
- Published
- 2019
- Full Text
- View/download PDF
22. Control of binary states of ferroic orders in bi-domain BiFeO3 nanoislands
- Author
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Oleg A. Ageev, Damien McGrouther, A. Ouvrard, Maxime Bavencoffe, Natalia Alyabyeva, A. S. Kolomiytsev, Ionela Lindfors-Vrejoiu, M. S. Solodovnik, Laboratoire de Physique de la Matière Condensée (LPMC), Collège de France (CdF (institution))-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
focused ion beam ,binary states ,ferroelectric domains ,Ferroelasticity ,Materials science ,Physics and Astronomy (miscellaneous) ,finite element method ,Flexoelectricity ,ferroelectric switching ,domain wall ,02 engineering and technology ,01 natural sciences ,Electric field ,0103 physical sciences ,Multiferroics ,ferroelasticity ,010302 applied physics ,Condensed matter physics ,Conductive atomic force microscopy ,BiFeO3 thin films ,conductive atomic force microscopy ,021001 nanoscience & nanotechnology ,Polarization (waves) ,Ferroelectricity ,Piezoresponse force microscopy ,flexoelectricity ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,piezoresponse force microscopy ,0210 nano-technology - Abstract
International audience; Selective control of the switching path in multiferroics such as BiFeO3 (BFO) is one of the main challenge for the design of non-volatile memories based on magnetoelectric coupling. Here, we demonstrate an alternative way to control binary states of ferroic orders (ferroelectric or ferroelastic) using an array of BFO nanoislands exhibiting two ferroelectric domains. The study of electronic transport properties and domain orientations using atomic force microscopy (AFM) based techniques enabled us to determine electric and mechanical parameters at which ferroelectric and ferroelastic resistive switching can be observed. Ferroelastic switching was associated with a symmetry-breaking induced by electromechanical coupling between the AFM tip and the BFO thin film. It led to out-ofplane polarization pinning that allows performing only in-plane switching accompanied with nucleation and propagation of a conductive domain wall. Nanoislands exhibited binary states of high (OFF) and low resistance (ON) controlled by the tip contact force and the external electric field, without scaling effect (down to 50 nm). High performance characteristics with up to 10 4 OFF/ON ratio, good endurance and retention characteristics were evidenced. Binary states of different ferroic orders with selective control of switching mechanisms by flexoelectric effect can find potential application in non-volatile memory with multilevel data storage capacity.
- Published
- 2020
23. Holographic imaging of electromagnetic fields via electron-light quantum interference
- Author
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F. J. García de Abajo, Gabriele Berruto, Giovanni Maria Vanacore, Damien McGrouther, Enrico Pomarico, Tom T. A. Lummen, R. J. Lamb, Tatiana Latychevskaia, I. Madan, Fabrizio Carbone, Madan, I, Vanacore, G, Pomarico, E, Berruto, G, Lamb, R, Mcgrouther, D, Lummen, T, Latychevskaia, T, Garcia de Abajo, F, and Carbone, F
- Subjects
Photon ,Attosecond ,Holography ,Physics::Optics ,02 engineering and technology ,01 natural sciences ,Signal ,law.invention ,Superposition principle ,Computer Science::Emerging Technologies ,Optics ,Interference (communication) ,law ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,Physics::Chemical Physics ,010306 general physics ,Research Articles ,Computer Science::Information Theory ,Ultrafast Electron Microscopy, Holography, Plasmons, Quantum Optics ,Quantum optics ,Physics ,Multidisciplinary ,business.industry ,SciAdv r-articles ,021001 nanoscience & nanotechnology ,0210 nano-technology ,business ,Ultrashort pulse ,Research Article - 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., Science Advances, 5 (5), ISSN:2375-2548
- Published
- 2018
24. Antiferromagnetic-ferromagnetic phase domain development in nanopatterned FeRh islands
- Author
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K. Fallon, Rowan Temple, Jamie Massey, Francesco Maccherozzi, Christopher H. Marrows, Stephen McVitie, T. A. Moore, Damien McGrouther, R. J. Lamb, Sophie A. Morley, Sarnjeet S. Dhesi, and Trevor P. Almeida
- Subjects
Phase transition ,Condensed Matter - Materials Science ,Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Magnetic circular dichroism ,Transition temperature ,Nucleation ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,cond-mat.mtrl-sci ,Photoemission electron microscopy ,Ferromagnetism ,0103 physical sciences ,Scanning transmission electron microscopy ,Antiferromagnetism ,General Materials Science ,010306 general physics ,0210 nano-technology - Abstract
The antiferromagnetic-to-ferromagnetic phase transition in B2-ordered FeRh is imaged in laterally confined nanopatterned islands using photoemission electron microscopy with x-ray magnetic circular dichroism contrast. The resulting magnetic images directly detail the progression in the shape and size of the FM phase domains during heating and cooling through the transition. In 5-\ud μ\ud m\ud -square islands this domain development during heating is shown to proceed in three distinct modes—nucleation, growth, and merging—each with subsequently greater energy costs. In 0.5-\ud μ\ud m\ud islands, which are smaller than the typical final domain size, the growth mode is stunted and the transition temperature is found to be reduced by 20 K. The modification to the transition temperature is found by high-resolution scanning transmission electron microscopy to be due to a 100-nm chemically disordered edge grain present as a result of ion implantation damage during the patterning. FeRh has unique possibilities for magnetic memory applications; the inevitable changes to its magnetic properties due to subtractive nanofabrication will need to be addressed in future work in order to progress from sheet films to suitable patterned devices.
- Published
- 2018
25. Nanomagnets: Strain Anisotropy and Magnetic Domains in Embedded Nanomagnets (Small 52/2019)
- Author
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Rantej Bali, Anna Semisalova, Gary W. Paterson, Oleksii M. Volkov, Gregor Hlawacek, Jürgen Fassbender, Damien McGrouther, Denys Makarov, Kay Potzger, Magnus Nord, Ian MacLaren, Vico Liersch, Jürgen Lindner, and Attila Kákay
- Subjects
Biomaterials ,Materials science ,Magnetic domain ,Condensed matter physics ,Strain anisotropy ,General Materials Science ,General Chemistry ,Nanomagnet ,Biotechnology - Published
- 2019
26. Differential Phase Contrast Imaging of the Magnetostructural Transition and Phase Boundary Motion in Uniform and Gradient-doped FeRh-based Thin Films
- Author
-
Christopher H. Marrows, Thomas R. Moore, Rowan Temple, Damien McGrouther, Laura Clark, Stephen McVitie, Trevor P. Almeida, and Jamie Massey
- Subjects
Phase boundary ,Materials science ,Condensed matter physics ,Doping ,Motion (geometry) ,Thin film ,Differential phase contrast ,Instrumentation ,QC - Abstract
No abstract available.
- Published
- 2019
27. Author Correction: Attosecond coherent control of free-electron wave functions using semi-infinite light fields
- Author
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Giovanni Maria Vanacore, Kangpeng Wang, Damien McGrouther, Enrico Pomarico, R. J. Lamb, Ido Kaminer, F. Javier García de Abajo, Gabriele Berruto, Brett Barwick, Fabrizio Carbone, and I. Madan
- Subjects
Free electron model ,Physics ,Multidisciplinary ,Semi-infinite ,Attosecond ,Published Erratum ,Science ,General Physics and Astronomy ,Mistake ,General Chemistry ,General Biochemistry, Genetics and Molecular Biology ,Mathematical equations ,Classical mechanics ,Coherent control ,lcsh:Q ,lcsh:Science ,Wave function - Abstract
The authors became aware of a mistake in the original version of this Article. Specifically, an extra factor γ was incorrectly included in a number of mathematical equations and expressions. As a result of this, a number of changes have been made to both the PDF and the HTML versions of the Article. A full list of these changes is available online.
- Published
- 2019
28. Back-scattered electron visualization of ferroelectric domains in a BiFeO 3 epitaxial film
- Author
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Ionela Lindfors-Vrejoiu, Oleg A. Ageev, Damien McGrouther, Natalia Alyabyeva, A. Ouvrard, Institut des Sciences Moléculaires d'Orsay (ISMO), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Physikalisches Institut [Köln], Universität zu Köln, Southern Federal University [Rostov-on-Don] (SFEDU), SUPA School of Physics and Astronomy [Glasgow], and University of Glasgow
- Subjects
010302 applied physics ,Diffraction ,Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Scanning electron microscope ,02 engineering and technology ,Electron ,021001 nanoscience & nanotechnology ,Channelling ,Polarization (waves) ,01 natural sciences ,Ferroelectricity ,Condensed Matter::Materials Science ,Electron diffraction ,0103 physical sciences ,Microscopy ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,[PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det] ,0210 nano-technology ,ComputingMilieux_MISCELLANEOUS - Abstract
Three-dimensional orientation of the ferroelectric (FE) domain structure of a BiFeO3 epitaxial film was investigated by scanning electron microscopy (SEM) using back-scattered electrons and piezoresponse-force microscopy (PFM). By changing the crystallographic orientation of the sample and the electron collection angle relative to the detector, we establish a link between the orientation of polarization vectors (out-of-plane and in-plane) in the BiFeO3 film and the back-scattered electron image contrast in agreement with PFM investigations. The different FE polarization states in the domains correspond to altered crystalline environments for the impingent primary beam electrons. We postulate that the resultant back-scattered electron domain contrast arises as a result of either differential absorption (through a channelling effect) or through back-diffraction from the sample, which leads to a projected diffraction pattern super-imposed with the diffuse conventional back-scattered electron intensity. We de...
- Published
- 2017
29. Core–shell GaN–ZnO moth-eye nanostructure arrays grown on a-SiO2/Si (1 1 1) as a basis for improved InGaN-based photovoltaics and LEDs
- Author
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Teresa Monteiro, D. J. Rogers, Abdallah Ougazzaden, Damien McGrouther, Tarik Moudakir, Marco Peres, Michael Molinari, M.J. Soares, F. Hosseini Teherani, A.J. Neves, Philippe Bove, Michel Troyon, R. McClintock, M. Abid, Manijeh Razeghi, Simon Gautier, V. E. Sandana, H.-J. Drouhin, and J. N. Chapman
- Subjects
Materials science ,business.industry ,Scanning electron microscope ,Nanowire ,Cathodoluminescence ,Condensed Matter Physics ,Epitaxy ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Pulsed laser deposition ,Hardware and Architecture ,law ,Photovoltaics ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Light-emitting diode ,Wurtzite crystal structure - Abstract
Self-forming, vertically-aligned, ZnO moth-eye-like nanoarrays were grown by catalyst-free pulsed laser deposition on a-SiO2/Si (1 1 1) substrates. X-Ray Diffraction (XRD) and Cathodoluminescence (CL) studies indicated that nanostructures were highly c-axis oriented wurtzite ZnO with strong near band edge emission. The nanostructures were used as templates for the growth of non-polar GaN by metal organic vapor phase epitaxy. XRD, scanning electron microscopy, energy dispersive X-ray microanalysis and CL revealed ZnO encapsulated with GaN, without evidence of ZnO back-etching. XRD showed compressive epitaxial strain in the GaN, which is conducive to stabilization of the higher indium contents required for more efficient green light emitting diode (LED) and photovoltaic (PV) operation. Angular-dependent specular reflection measurements showed a relative reflectance of less than 1% over the wavelength range of 400–720 nm at all angles up to 60°. The superior black-body performance of this moth-eye-like structure would boost LED light extraction and PV anti-reflection performance compared with existing planar or nanowire LED and PV morphologies. The enhancement in core conductivity, provided by the ZnO, would also improve current distribution and increase the effective junction area compared with nanowire devices based solely on GaN.
- Published
- 2015
30. Aberration corrected Lorentz scanning transmission electron microscopy
- Author
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K. J. O'Shea, M. J. Benitez, S. McFadzean, Donald A. MacLaren, Stephen McVitie, and Damien McGrouther
- Subjects
Physics ,Microscope ,Contrast transfer function ,business.industry ,Resolution (electron density) ,Scanning confocal electron microscopy ,equipment and supplies ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Optics ,law ,Transmission electron microscopy ,Scanning transmission electron microscopy ,Microscopy ,Electron microscope ,business ,Instrumentation - Abstract
We present results from an aberration corrected scanning transmission electron microscope which has been customised for high resolution quantitative Lorentz microscopy with the sample located in a magnetic field free or low field environment. We discuss the innovations in microscope instrumentation and additional hardware that underpin the imaging improvements in resolution and detection with a focus on developments in differential phase contrast microscopy. Examples from materials possessing nanometre scale variations in magnetisation illustrate the potential for aberration corrected Lorentz imaging as a tool to further our understanding of magnetism on this lengthscale.
- Published
- 2015
31. Filming the formation and fluctuation of skyrmion domains by cryo-Lorentz transmission electron microscopy
- Author
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Giulia F. Mancini, Henrik M. Rønnow, Edoardo Baldini, Jonathan S. White, Thierry Giamarchi, Ping Huang, Yoshie Murooka, Tatiana Latychevskaia, Damien McGrouther, Fabrizio Carbone, Jayaraman Rajeswari, Marco Cantoni, and Arnaud Magrez
- Subjects
Phase transition ,skyrmions ,Lorentz transformation ,FOS: Physical sciences ,ddc:500.2 ,02 engineering and technology ,01 natural sciences ,symbols.namesake ,Lattice (order) ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,strongly correlated systems ,010306 general physics ,Physics ,Multidisciplinary ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Skyrmion ,021001 nanoscience & nanotechnology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Magnetic field ,Transmission electron microscopy ,Lorentz transmission electron microscopy ,Physical Sciences ,symbols ,magnetic materials ,0210 nano-technology ,skyrmion dynamics - Abstract
Magnetic skyrmions are promising candidates as information carriers in logic or storage devices thanks to their robustness, guaranteed by the topological protection, and their nanometric size. Currently, little is known about the influence of parameters such as disorder, defects or external stimuli, on the long-range spatial distribution and temporal evolution of the skyrmion lattice. Here, using a large (7.3x7.3{\mu}m$^{2}$) single crystal nano-slice of Cu$_{2}$OSeO$_{3}$, we image up to 70,000 skyrmions, by means of cryo-Lorentz Transmission Electron Microscopy as a function of the applied magnetic field. The emergence of the skyrmion lattice from the helimagnetic phase is monitored, revealing the existence of a glassy skyrmion phase at the phase transition field, where patches of an octagonally distorted skyrmion lattice are also discovered. In the skyrmion phase, dislocations are shown to cause the emergence and switching between domains with different lattice orientations and the temporal fluctuations of these domains is filmed. These results demonstrate the importance of direct-space and real-time imaging of skyrmion domains for addressing both their long-range topology and stability., Comment: 31 pages (16 + 15 supplementary material),17 figures (4 + 13 supplementary material)
- Published
- 2015
32. Fabrication of high quality plan-view TEM specimens using the focused ion beam
- Author
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K. J. O'Shea, S. Hühn, Damien McGrouther, Vasily Moshnyaga, M. Jungbauer, Ciaran Ferguson, and Donald A. MacLaren
- Subjects
Fabrication ,Materials science ,business.industry ,Scanning confocal electron microscopy ,General Physics and Astronomy ,Nanotechnology ,Cell Biology ,Electron ,Focused ion beam ,Electron spectroscopy ,law.invention ,Structural Biology ,Transmission electron microscopy ,law ,Optoelectronics ,General Materials Science ,Thin film ,Electron microscope ,business - 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 La 0.67 Sr 0.33 MnO 3 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.
- Published
- 2014
33. Magnetic scanning gate microscopy of CoFeB lateral spin valve
- Author
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Damien McGrouther, Vladimir Antonov, Héctor Corte-León, Patryk Krzysteczko, Rhodri Mansell, Stephen McVitie, Alexander Fernández Scarioni, Hans Werner Schumacher, Russell P. Cowburn, Olga Kazakova, and David Cox
- Subjects
Materials science ,Condensed matter physics ,Magnetoresistance ,Spin valve ,General Physics and Astronomy ,Scanning gate microscopy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,lcsh:QC1-999 ,Magnetic field ,Scanning probe microscopy ,Dipole ,Condensed Matter::Materials Science ,Hall effect ,0103 physical sciences ,Spin diffusion ,010306 general physics ,0210 nano-technology ,lcsh:Physics - Abstract
Devices comprised of CoFeB nanostructures with perpendicular magnetic anisotropy and non-magnetic Ta channel were operated in thermal lateral spin valve (LSV) mode and studied by magnetotransport measurements and magnetic scanning gate microscopy (SGM). Due to the short spin diffusion length of Ta, the spin diffusion signal was suppressed, allowing the study of the contribution from the anomalous Nernst (ANE) and anomalous Hall effects (AHE). The magnetotransport measurements identified the switching fields of the CoFeB nanostructures and demonstrated a combination of AHE and ANE when the devices were operated in thermally-driven spin-injection mode. Modified scanning probe microscopy probes were fabricated by placing a NdFeB magnetic bead (MB) on the apex of a commercial Si probe. The dipole magnetic field distribution around the MB was characterized by using differential phase contrast technique and direct measurement of the switching field induced by the bead in the CoFeB nanodevices. Using SGM we demonstrate the influence of localized magnetic field on the CoFeB nanostructures near the non-magnetic channel. This approach provides a promising route towards the study of thermal and spin diffusion effects using local magnetic fields.Devices comprised of CoFeB nanostructures with perpendicular magnetic anisotropy and non-magnetic Ta channel were operated in thermal lateral spin valve (LSV) mode and studied by magnetotransport measurements and magnetic scanning gate microscopy (SGM). Due to the short spin diffusion length of Ta, the spin diffusion signal was suppressed, allowing the study of the contribution from the anomalous Nernst (ANE) and anomalous Hall effects (AHE). The magnetotransport measurements identified the switching fields of the CoFeB nanostructures and demonstrated a combination of AHE and ANE when the devices were operated in thermally-driven spin-injection mode. Modified scanning probe microscopy probes were fabricated by placing a NdFeB magnetic bead (MB) on the apex of a commercial Si probe. The dipole magnetic field distribution around the MB was characterized by using differential phase contrast technique and direct measurement of the switching field induced by the bead in the CoFeB nanodevices. Using SGM we demo...
- Published
- 2017
34. Beam-induced Fe nanopillars as tunable domain-wall pinning sites
- Author
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B Bert Koopmans, TH Tim Ellis, Maj Mark van der Heijden, Hjm Henk Swagten, Damien McGrouther, Reinoud Lavrijsen, C Carsten Daniels, JH Jeroen Franken, Physics of Nanostructures, Applied Physics and Science Education, and Eindhoven Hendrik Casimir institute
- Subjects
Materials science ,Nanostructure ,Magnetic domain ,Condensed matter physics ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Domain wall (magnetism) ,Nanosensor ,Transmission electron microscopy ,Electrochemistry ,Perpendicular ,Beam (structure) ,Nanopillar - Abstract
Focused-electron-beam-induced deposition (FEBID) is employed to create freestanding magnetic nanostructures. By growing Fe nanopillars on top of a perpendicular magnetic domain wall (DW) conduit, pinning of the DWs is observed due to the stray fields emanating from the nanopillar. Furthermore, a different DW pinning behavior is observed between the up and down magnetic states of the pillar, allowing to deduce the switching fields of the pillar in a novel way. The implications of these results are two-fold: not only can 3-dimensional nano-objects be used to control DW motion in applications, it is also proposed that DW motion is a unique tool to probe the magnetic properties of nano-objects.
- Published
- 2014
35. Pixelated STEM detectors: opportunities and challenges
- Author
-
Andrew Ross, Alastair Doye, Damien McGrouther, Rantej Bali, Robert H. Hadfield, Magnus Nord, Ian MacLaren, M. J. Hart, Archan Banerjee, and Matus Krajnak
- Subjects
Materials science ,Magnetic domain ,business.industry ,Lorentz microscopy ,Detector ,Optoelectronics ,Medipix ,business ,Amorphous solid - Published
- 2016
36. Quantitative Differential Phase Contrast Imaging of the Magnetostructural Transition and Current-driven Motion of Domain Walls in FeRh Thin Films
- Author
-
Damien McGrouther, Thomas A. Moore, Stephen McVitie, K. Fallon, Rowan Temple, Gary W. Paterson, Trevor P. Almeida, Jamie Massey, and Christopher H. Marrows
- Subjects
Materials science ,Condensed matter physics ,Motion (geometry) ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Domain (software engineering) ,Current (fluid) ,Thin film ,0210 nano-technology ,Differential phase contrast ,Instrumentation - Abstract
No abstract available.
- Published
- 2018
37. Investigating Skyrmions Using Lorentz Transmission Electron Microscopy
- Author
-
Giulia F. Mancini, Ping Huang, Rajeswari Jayaraman, Damien McGrouther, Thierry Giamarchi, Jonathan S. White, Fabrizio Carbone, Yoshie Murooka, Tatiana Latychevskaia, Arnaud Magrez, Edoardo Baldini, Alex Kruchkov, Henrik M. Rønnow, and Marco Cantoni
- Subjects
010302 applied physics ,Physics ,Condensed matter physics ,Skyrmion ,Lorentz transformation ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,symbols.namesake ,Transmission electron microscopy ,0103 physical sciences ,symbols ,0210 nano-technology ,Instrumentation - Published
- 2018
38. Imaging Structure and Magnetisation in New Ways Using 4D STEM
- Author
-
Rantej Bali, Damien McGrouther, Jürgen Faßbender, Suzanne Conner, Mohsen Danaie, Gregor Hlawacek, Christopher S. Allen, Angus I. Kirkland, Magnus Nord, Ian MacLaren, and Jürgen Lindner
- Subjects
010302 applied physics ,Magnetization ,Materials science ,Condensed matter physics ,0103 physical sciences ,Structure (category theory) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,0210 nano-technology ,01 natural sciences ,Instrumentation - Published
- 2018
39. Imaging and controlling plasmonic interference fields at buried interfaces
- Author
-
Damien McGrouther, Tom T. A. Lummen, Fabrizio Carbone, R. J. Lamb, Thomas LaGrange, Gabriele Berruto, F. Javier García de Abajo, Brett Barwick, and Lucal Dal Negro
- Subjects
Materials science ,Science ,FOS: Physical sciences ,General Physics and Astronomy ,Physics::Optics ,02 engineering and technology ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Article ,law.invention ,Condensed Matter::Materials Science ,Optics ,Interference (communication) ,law ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,Thin film ,010306 general physics ,Plasmon ,QC ,Condensed Matter - Materials Science ,Multidisciplinary ,Condensed Matter - Mesoscale and Nanoscale Physics ,Graphene ,business.industry ,Materials Science (cond-mat.mtrl-sci) ,Heterojunction ,General Chemistry ,021001 nanoscience & nanotechnology ,Femtosecond ,Group velocity ,Optoelectronics ,Nanometre ,0210 nano-technology ,business - 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.
- Published
- 2016
40. TEM characterization of GaSb grown on single crystal offcut Silicon (001)
- Author
-
Ian MacLaren, M. J. Steer, Alan J. Craven, H. L. Porter, I.G. Thayne, and Damien McGrouther
- Subjects
010302 applied physics ,Materials science ,Silicon ,business.industry ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Characterization (materials science) ,chemistry ,0103 physical sciences ,Optoelectronics ,0210 nano-technology ,business ,Instrumentation ,Single crystal - Published
- 2017
41. Formation of Magnetic Structure by Domain Wall Confinement in Nanoconstriction
- Author
-
Christopher H. Marrows, Hiroyuki Awano, Stephen McVitie, J. N. Chapman, Duc-The Ngo, Damien McGrouther, and M. C. Hickey
- Subjects
Physics ,Magnetic structure ,Condensed matter physics ,Magnetic domain ,Magnetoresistance ,equipment and supplies ,Magnetostatics ,Electronic, Optical and Magnetic Materials ,Magnetic anisotropy ,Magnetization ,Domain wall (magnetism) ,Transmission electron microscopy ,Electrical and Electronic Engineering ,human activities - Abstract
We present here a study of exploiting Lorentz transmission electron microscopy to observe the magnetic structure in a nanobridge formed by confining a magnetic domain wall. The domain wall is nucleated in an elliptical pad by magnetization reversal and is driven to be pinned at the constriction to form a complex magnetic structure. High-resolution Lorentz microscopy shows that such a structure is composed by a mixture of S and C states of smooth rotation of the magnetization through the nanobridge rather than a conventional single wall as observed previously. This confinement contributes a domain wall resistance observed via anisotropic magnetoresistance presented previously. A serial transformation from S state to S/C mixture, to C state and finally to S state of the topology of the flux is evidently confirmed.
- Published
- 2011
42. Investigation of Microstructural and Electrochemical Properties of Impregnated (La,Sr)(Ti,Mn)O3±δ as a Potential Anode Material in High-Temperature Solid Oxide Fuel Cells
- Author
-
Jung Hyun Kim, Damien McGrouther, John T. S. Irvine, David Noel Miller, and Harald Schlegl
- Subjects
Materials science ,Scanning electron microscope ,General Chemical Engineering ,Analytical chemistry ,Oxide ,General Chemistry ,Atmospheric temperature range ,Electrochemistry ,Micrography ,Anode ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Solid oxide fuel cell ,Power density - Abstract
The microstructural and electrochemical properties of La0.4Sr0.6Ti0.8Mn0.2O3±δ (LSTM) fabricated via liquid-phase impregnation have been investigated for solid oxide fuel cell (SOFC) applications. Scanning electron micrography (SEM) showed that LSTM uniformly covers the porous scaffold when heated in an oxidizing atmosphere, which transforms to fine particles when reduced. The electrical conductivity of a 10 wt % CeO2–50 wt % LSTM–8 mol % yttria-stabilized zirconia (8YSZ) composite anode was higher than that of a 50 wt % LSTM–8YSZ anode and was stable at 700, 800, and 900 °C under reducing conditions. When the 50 wt % LSTM-8YSZ was used as an anode, power densities of the sample were
- Published
- 2011
43. The Effect of Substrate Surface Oxides on the Bonding of NiCr Alloy Particles HVAF Thermally Sprayed onto Aluminum Substrates
- Author
-
Margaret Hyland, Paul Munroe, Andreas Markwitz, William J. Trompetter, and Damien McGrouther
- Subjects
Materials science ,Diffusion ,Metallurgy ,Oxide ,chemistry.chemical_element ,Substrate (electronics) ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Metal ,chemistry.chemical_compound ,chemistry ,Aluminium ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Particle ,Nichrome ,Deformation (engineering) ,Composite material - Abstract
The effect of substrate surface oxides on splat-substrate bonding was investigated by thermally spraying NiCr particles onto aluminum substrates with surface oxide layers grown hydrothermally and electrochemically. Cross sections of bonded solid and molten splats revealed substantial deformation of both the substrate and the surface oxide. In spite of the substantial substrate deformation, there was no significant loss of the surface oxide material and there was no observed diffusion of the substrate oxide into the NiCr particle or vice versa. For solid splats, the substrate oxide was still present over the entire splat-substrate interface, however for molten splats, the oxide had been penetrated in several locations allowing close proximity of the splat metal to the substrate metal. These results strengthen the theory that oxide layers impede bonding and that successful bonding occurs only when the surface oxide is substantially deformed or disrupted to produce mechanically interlocking features at the interface.
- Published
- 2010
44. Bridging the Gap: Polymer Nanowire Devices
- Author
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Damien McGrouther, R. Newbury, Neil T. Kemp, and Jack W. Cochrane
- Subjects
Conductive polymer ,chemistry.chemical_compound ,Bridging (networking) ,Materials science ,chemistry ,Polyaniline nanofibers ,Mechanics of Materials ,Mechanical Engineering ,Polyaniline ,Nanowire ,GAP polymer ,General Materials Science ,Nanotechnology - Published
- 2007
45. Atom probe specimen fabrication methods using a dual FIB/SEM
- Author
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Damien McGrouther, David W. Saxey, Tomoyuki Honma, Julie M. Cairney, and Simon P. Ringer
- Subjects
In situ ,Materials science ,business.industry ,Nanotechnology ,Atom probe ,Focused ion beam ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Electropolishing ,law ,Fabrication methods ,Optoelectronics ,Specimen preparation ,business ,Instrumentation - 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.
- Published
- 2007
46. Three dimensional imaging of deformation modes in TiN-based thin film coatings
- Author
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Julie M. Cairney, Paul Munroe, Damien McGrouther, Mark Hoffman, and L.W. Ma
- Subjects
Materials science ,Ion beam ,Metals and Alloys ,Surfaces and Interfaces ,Deformation (meteorology) ,Nanoindentation ,engineering.material ,Focused ion beam ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Crystallography ,Brittleness ,Coating ,Indentation ,Materials Chemistry ,engineering ,Thin film ,Composite material - Abstract
A TiN thin film coating, approximately 4 μm in thickness, deposited on a ductile steel substrate, was subject to surface deformation via nanoindentation using a spherical indenter, 5 μm in radius, with loads up to 500 mN. Pop-ins were observed during loading, which are characteristic of the onset of cracking and the formation of shear steps at the coating–substrate interface. Focused ion beam microscopy was used to prepare cross-sections through the indentation that revealed the presence of both intercolumnar and inclined cracks. Three-dimensional reconstructions of the deformation zone beneath the indentation were performed using a dual-beam focus ion beam instrument. These constructions provided more detailed images of the morphology of cracks, which were observed to be consistent with theoretical models of plastic deformation of such brittle coatings.
- Published
- 2007
47. Pixelated detectors and improved efficiency for magnetic imaging in STEM differential phase contrast
- Author
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Matus, Krajnak, Damien, McGrouther, Dzmitry, Maneuski, Val O', Shea, and Stephen, McVitie
- Abstract
The application of differential phase contrast imaging to the study of polycrystalline magnetic thin films and nanostructures has been hampered by the strong diffraction contrast resulting from the granular structure of the materials. In this paper we demonstrate how a pixelated detector has been used to detect the bright field disk in aberration corrected scanning transmission electron microscopy (STEM) and subsequent processing of the acquired data allows efficient enhancement of the magnetic contrast in the resulting images. Initial results from a charged coupled device (CCD) camera demonstrate the highly efficient nature of this improvement over previous methods. Further hardware development with the use of a direct radiation detector, the Medipix3, also shows the possibilities where the reduction in collection time is more than an order of magnitude compared to the CCD. We show that this allows subpixel measurement of the beam deflection due to the magnetic induction. While the detection and processing is data intensive we have demonstrated highly efficient DPC imaging whereby pixel by pixel interpretation of the induction variation is realised with great potential for nanomagnetic imaging.
- Published
- 2015
48. Nanoscale Mapping of the Magnetic Properties of (111)-Oriented La(0.67)Sr(0.33)MnO3
- Author
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Kerry J, O'Shea, Donald A, MacLaren, Damien, McGrouther, Danny, Schwarzbach, Markus, Jungbauer, Sebastian, Hühn, Vasily, Moshnyaga, and Robert L, Stamps
- 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.
- Published
- 2015
49. On the origin of differential phase contrast at a locally charged and globally charge-compensated domain boundary in a polar-ordered material
- Author
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Roland Schierholz, Rafal E. Dunin-Borkowski, LiQiu Wang, Juri Barthel, Ian MacLaren, Alan J. Craven, András Kovács, Stephen McVitie, and Damien McGrouther
- Subjects
Diffraction ,Boundary (topology) ,02 engineering and technology ,01 natural sciences ,Signal ,chemistry.chemical_compound ,Condensed Matter::Materials Science ,Optics ,Electric field ,ddc:570 ,0103 physical sciences ,Scanning transmission electron microscopy ,Instrumentation ,Bismuth ferrite ,010302 applied physics ,Physics ,Condensed matter physics ,business.industry ,021001 nanoscience & nanotechnology ,Ferroelectricity ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,chemistry ,Modulation ,0210 nano-technology ,business - Abstract
Ultramicroscopy 154, 57-63 (2015). doi:10.1016/j.ultramic.2015.03.016, Published by Elsevier Science, Amsterdam
- Published
- 2015
50. Engineering magnetic domain-wall structure in Permalloy nanowires
- Author
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S. McFadzean, M. J. Benitez, Damien McGrouther, R. J. Lamb, Christopher H. Marrows, M. A. Basith, Donald A. MacLaren, Stephen McVitie, and Aleš Hrabec
- Subjects
Permalloy ,Condensed Matter - Materials Science ,Materials science ,Magnetic domain ,business.industry ,Nanowire ,General Physics and Astronomy ,chemistry.chemical_element ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Domain (software engineering) ,chemistry ,Computer data storage ,Optoelectronics ,Gallium ,Material properties ,business ,Beam (structure) ,QC - Abstract
Using Lorentz transmission electron microscopy we investigate the behavior of domain walls pinned at non-topographic defects in Cr(3 nm)/Permalloy(10 nm)/Cr(5 nm) nanowires of width 500 nm. The pinning sites consist of linear defects where magnetic properties are modified by a Ga ion probe with diameter ~ 10 nm using a focused ion beam microscope. We study the detailed change of the modified region (which is on the scale of the focused ion spot) using electron energy loss spectroscopy and differential phase contrast imaging on an aberration (Cs) corrected scanning transmission electron microscope. The signal variation observed indicates that the region modified by the irradiation corresponds to ~ 40-50 nm despite the ion probe size of only 10 nm. Employing the Fresnel mode of Lorentz transmission electron microscopy, we show that it is possible to control the domain wall structure and its depinning strength not only via the irradiation dose but also the line orientation., Comment: Accepted for publication in Physical Review Applied
- Published
- 2015
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