Author
Magnus Nord
Other affiliations: Norwegian University of Science and Technology, University of Antwerp
Bio: Magnus Nord is an academic researcher from University of Glasgow. The author has contributed to research in topics: Scanning transmission electron microscopy & Thin film. The author has an hindex of 16, co-authored 60 publications receiving 752 citations. Previous affiliations of Magnus Nord include Norwegian University of Science and Technology & University of Antwerp.
Papers
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TL;DR: This work presents a free and open source software tool for analysing both the position and shapes of atomic columns in STEM-images, using 2-D elliptical Gaussian distributions, and can extract changes in the lattice parameters and shape of A-cation columns from annular dark field images of perovskite oxide heterostructures.
Abstract: Scanning transmission electron microscopy (STEM) data with atomic resolution can contain a large amount of information about the structure of a crystalline material. Often, this information is hard to extract, due to the large number of atomic columns and large differences in intensity from sublattices consisting of different elements. In this work, we present a free and open source software tool for analysing both the position and shapes of atomic columns in STEM-images, using 2-D elliptical Gaussian distributions. The software is tested on variants of the perovskite oxide structure. By first fitting the most intense atomic columns and then subtracting them, information on all the projected sublattices can be obtained. From this, we can extract changes in the lattice parameters and shape of A-cation columns from annular dark field images of perovskite oxide heterostructures. Using annular bright field images, shifts in oxygen column positions are also quantified in the same heterostructure. The precision of determining the position of atomic columns is compared between STEM data acquired using standard acquisition, and STEM-images obtained as an image stack averaged after using non-rigid registration.
173 citations
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TL;DR: Francisco de la Peña, Tomas Ostasevicius, Vidar Tonaas Fauske, Pierre Burdet, Petras Jokubauskas, Magnus Nord, Mike Sarahan, Eric Prestat, Duncan N. Johnstone, Joshua Taillon, Jan Caron, Tom Furnival, Katherine E. MacArthur, Alberto Eljarrat, Stefano Mazzucco, Vadim Migunov, Thomas Aarholt, Michael Walls, Florian Winkler, Gaël Donval, Ben Martineau, Andreas Garman
Abstract: Francisco de la Peña, Tomas Ostasevicius, Vidar Tonaas Fauske, Pierre Burdet, Petras Jokubauskas, Magnus Nord, Mike Sarahan, Eric Prestat, Duncan N. Johnstone, Joshua Taillon, Jan Caron, Tom Furnival, Katherine E. MacArthur, Alberto Eljarrat, Stefano Mazzucco, Vadim Migunov, Thomas Aarholt, Michael Walls, Florian Winkler, Gaël Donval, Ben Martineau, Andreas Garmannslund, Luiz-Fernando Zagonel and Ilya Iyengar
59 citations
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TL;DR: In this paper, the authors report on the optimisation of amorphous molybdenum silicide thin film growth for superconducting nanowire single photon detector (SNSPD/SSPD) applications.
Abstract: We report on the optimisation of amorphous molybdenum silicide thin film growth for
superconducting nanowire single photon detector (SNSPD/SSPD) applications Molybdenum silicide
was deposited via co-sputtering from Mo and Si targets in an Ar atmosphere The superconducting
transition temperature (Tc) and sheet resistance (Rs) were measured as a function of thickness and
compared to several theoretical models for disordered superconducting films Superconducting and
optical properties of amorphous materials are very sensitive to short- (up to 1 nm) and medium-range
order (~1-3 nm) in the atomic structure Fluctuation electron microscopy (FEM) studies showed that
the films assumed an A15-like medium-range order Electron energy loss spectroscopy (EELS)
indicates that the film stoichiometry was close to Mo83Si17, which is consistent with reports that many
other A15 structures with the nominal formula A3B show a significant non-stoichiometry with A:B >
3:1 Optical properties from ultraviolet (270 nm) to infrared (2200 nm) wavelengths were measured
via spectroscopic ellipsometry for 5 nm thick MoSi films indicating high long wavelength absorption
We also measured the current density as a function of temperature for nanowires patterned from a 10
nm thick MoSi film The current density at 36 K is 36 x 105A/cm2
for the widest wire studied (2003
nm), falling to 2 x 105A/cm2
for the narrowest (173 nm) This investigation confirms the excellent
suitability of MoSi for SNSPD applications and gives fresh insight into the properties of the
underlying materials
52 citations
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TL;DR: This work determines how, for a fixed total electron-budget, the available dose should be fractionated for maximum strain mapping precision and finds that reductions in scanning-artefacts of more than 70% are achievable with image series of 20-30 frames in length.
50 citations
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TL;DR: The fabrication of vertically aligned radial-junction solar cells from polycrystalline, low purity silicon starting material, formed into silicon core, silica sheath fibres using bulk glass draw techniques has the potential to reduce the energy cost and the silicon volume required for solar cell production.
Abstract: Vertically aligned radial-junction solar cell designs offer potential improvements over planar geometries, as carrier generation occurs close to the junction for all absorption depths, but most production methods still require a single crystal substrate. Here, we report on the fabrication of such solar cells from polycrystalline, low purity (99.98%) p-type silicon starting material, formed into silicon core, silica sheath fibres using bulk glass draw techniques. Short segments were cut from the fibres, and the silica was etched from one side, which exposed the core and formed a conical cavity around it. We then used vapour deposition techniques to create p-i-n junction solar cells. Prototype cells formed from single fibres have shown conversion efficiencies up to 3.6%, despite the low purity of the starting material. This fabrication method has the potential to reduce the energy cost and the silicon volume required for solar cell production. Simulations were performed to investigate the potential of the conical cavity around the silicon core for light collection. Absorption of over 90% of the incident light was predicted, over a wide range of wavelengths, using these structures in combination with a 10% volume fraction of silicon.
47 citations
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TL;DR: Electrical writing is combined in solid-state memory with electrical readout and the stored magnetic state is insensitive to and produces no external magnetic field perturbations, which illustrates the unique merits of antiferromagnets for spintronics.
Abstract: Manipulating a stubborn magnet Spintronics is an alternative to conventional electronics, based on using the electron's spin rather than its charge. Spintronic devices, such as magnetic memory, have traditionally used ferromagnetic materials to encode the 1's and 0's of the binary code. A weakness of this approach—that strong magnetic fields can erase the encoded information—could be avoided by using antiferromagnets instead of ferromagnets. But manipulating the magnetic ordering of antiferromagnets is tricky. Now, Wadley et al. have found a way (see the Perspective by Marrows). Running currents along specific directions in the thin films of the antiferromagnetic compound CuMnAs reoriented the magnetic domains in the material. Science, this issue p. 587; see also p. 558 Transport and optical measurements are used to demonstrate the switching of domains in the antiferromagnetic compound CuMnAs. [Also see Perspective by Marrows] Antiferromagnets are hard to control by external magnetic fields because of the alternating directions of magnetic moments on individual atoms and the resulting zero net magnetization. However, relativistic quantum mechanics allows for generating current-induced internal fields whose sign alternates with the periodicity of the antiferromagnetic lattice. Using these fields, which couple strongly to the antiferromagnetic order, we demonstrate room-temperature electrical switching between stable configurations in antiferromagnetic CuMnAs thin-film devices by applied current with magnitudes of order 106 ampere per square centimeter. Electrical writing is combined in our solid-state memory with electrical readout and the stored magnetic state is insensitive to and produces no external magnetic field perturbations, which illustrates the unique merits of antiferromagnets for spintronics.
756 citations
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TL;DR: The design and fabrication of a three-dimensional in vitro system to model vascular stenosis so that specific cellular interactions and responses to hemodynamic stimuli can be investigated and serve as an in vitro 3D culture system to investigate vascular pathogenesis.
Abstract: Vascular stenosis triggers adaptive cellular responses that induce adverse remodeling, which can progress to partial or complete vessel occlusion. Despite its severity, cellular interactions and biophysical cues that regulate pathological progression are poorly understood. We report the design and fabrication of a three-dimensional in vitro system to model vascular stenosis so that specific cellular interactions and responses to hemodynamic stimuli can be investigated. Tubular cellularized constructs (cytotubes) were produced using a collagen casting system to generate a stenotic arterial model. Fabrication methods were developed to create cytotubes containing co-cultured vascular cells, where cell viability, distribution, morphology, and contraction were examined (Figure). Fibroblasts, bone marrow primary cells, smooth muscle cells (SMCs), and endothelial cells (ECs) remained viable during culture and developed locationand time-dependent morphologies. We found cytotube contraction to depend on cellular composition, where SMC-EC co-cultures adopted intermediate contractile phenotypes between SMCand EC-only cytotubes. Our fabrication approach and resulting artery model can serve as an in vitro 3D culture system to investigate vascular pathogenesis.
570 citations
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TL;DR: The use of these four-dimensional STEM experiments for virtual diffraction imaging, phase, orientation and strain mapping, measurements of medium-range order, thickness and tilt of samples, and phase contrast imaging methods, including differential phase contrast, ptychography, and others are reviewed.
Abstract: Scanning transmission electron microscopy (STEM) is widely used for imaging, diffraction, and spectroscopy of materials down to atomic resolution. Recent advances in detector technology and computational methods have enabled many experiments that record a full image of the STEM probe for many probe positions, either in diffraction space or real space. In this paper, we review the use of these four-dimensional STEM experiments for virtual diffraction imaging, phase, orientation and strain mapping, measurements of medium-range order, thickness and tilt of samples, and phase contrast imaging methods, including differential phase contrast, ptychography, and others.
412 citations
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Institute of Cost and Management Accountants of Bangladesh1, Technische Universität München2, Université Paris-Saclay3, Max Planck Society4, University of Pittsburgh5, University of Science and Technology of China6, University of Salerno7, Forschungszentrum Jülich8, Cornell University9, University of Milano-Bicocca10, Universidade Nova de Lisboa11, Kyoto University12, Dresden University of Technology13, Uppsala University14, Nanosystems Initiative Munich15, École Polytechnique Fédérale de Lausanne16, National Institute for Materials Science17, MESA+ Institute for Nanotechnology18, Chalmers University of Technology19, University of Dundee20, Spanish National Research Council21, University of Cambridge22, University of Arkansas23, Polytechnic University of Valencia24, RWTH Aachen University25, Jožef Stefan Institute26
TL;DR: The Towards Oxide-Based Electronics (TO-BE) Action as mentioned in this paper has been recently running in Europe and has involved as participants several hundred scientists from 29 EU countries in a wide four-year project.
251 citations