Data Analysis WorkbeNch (DAWN) Basham, Mark; Filik, Jacob; Wharmby, Michael T. ...
Journal of synchrotron radiation,
20/May , Volume:
22, Issue:
3
Journal Article
Peer reviewed
Open access
Synchrotron light source facilities worldwide generate terabytes of data in numerous incompatible data formats from a wide range of experiment types. The Data Analysis WorkbeNch (DAWN) was developed ...to address the challenge of providing a single visualization and analysis platform for data from any synchrotron experiment (including single‐crystal and powder diffraction, tomography and spectroscopy), whilst also being sufficiently extensible for new specific use case analysis environments to be incorporated (e.g. ARPES, PEEM). In this work, the history and current state of DAWN are presented, with two case studies to demonstrate specific functionality. The first is an example of a data processing and reduction problem using the generic tools, whilst the second shows how these tools can be targeted to a specific scientific area.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
Mott transitions in real materials are first order and almost always associated with lattice distortions, both features promoting the emergence of nanotextured phases. This nanoscale ...self-organization creates spatially inhomogeneous regions, which can host and protect transient non-thermal electronic and lattice states triggered by light excitation. Here, we combine time-resolved X-ray microscopy with a Landau-Ginzburg functional approach for calculating the strain and electronic real-space configurations. We investigate V
2
O
3
, the archetypal Mott insulator in which nanoscale self-organization already exists in the low-temperature monoclinic phase and strongly affects the transition towards the high-temperature corundum metallic phase. Our joint experimental-theoretical approach uncovers a remarkable out-of-equilibrium phenomenon: the photo-induced stabilisation of the long sought monoclinic metal phase, which is absent at equilibrium and in homogeneous materials, but emerges as a metastable state solely when light excitation is combined with the underlying nanotexture of the monoclinic lattice.
Antiferromagnets have several favourable properties as active elements in spintronic devices, including ultra-fast dynamics, zero stray fields and insensitivity to external magnetic fields
. ...Tetragonal CuMnAs is a testbed system in which the antiferromagnetic order parameter can be switched reversibly at ambient conditions using electrical currents
. In previous experiments, orthogonal in-plane current pulses were used to induce 90° rotations of antiferromagnetic domains and demonstrate the operation of all-electrical memory bits in a multi-terminal geometry
. Here, we demonstrate that antiferromagnetic domain walls can be manipulated to realize stable and reproducible domain changes using only two electrical contacts. This is achieved by using the polarity of the current to switch the sign of the current-induced effective field acting on the antiferromagnetic sublattices. The resulting reversible domain and domain wall reconfigurations are imaged using X-ray magnetic linear dichroism microscopy, and can also be detected electrically. Switching by domain-wall motion can occur at much lower current densities than those needed for coherent domain switching.
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IJS, NUK, SBMB, UL, UM, UPUK
We report a novel microwave plasma enhanced chemical vapor deposition strategy for the efficient synthesis of multilayer graphene nanoflake films (MGNFs) on Si substrates. The constituent graphene ...nanoflakes have a highly graphitized knife‐edge structure with a 2–3 nm thick sharp edge and show a preferred vertical orientation with respect to the Si substrate as established by near‐edge X‐ray absorption fine structure spectroscopy. The growth rate is approximately 1.6 µm min−1, which is 10 times faster than the previously reported best value. The MGNFs are shown to demonstrate fast electron‐transfer (ET) kinetics for the Fe(CN)63−/4− redox system and excellent electrocatalytic activity for simultaneously determining dopamine (DA), ascorbic acid (AA) and uric acid (UA). Their biosensing DA performance in the presence of common interfering agents AA and UA is superior to other bare solid‐state electrodes and is comparable only to that of edge plane pyrolytic graphite. Our work here, establishes that the abundance of graphitic edge planes/defects are essentially responsible for the fast ET kinetics, active electrocatalytic and biosensing properties. This novel edge‐plane‐based electrochemical platform with the high surface area and electrocatalytic activity offers great promise for creating a revolutionary new class of nanostructured electrodes for biosensing, biofuel cells and energy‐conversion applications.
Metal‐free multilayer graphene nanoflake films are efficiently grown on Si by a simple method without use of catalysts. They are made of interlaced highly graphitized, abundant knife‐edge nanoflakes with a 2–3 nm thick edge and have a preferentially vertical orientation. They demonstrate well resolved simultaneous discrimination of dopamine, ascorbic acid, and uric acid, much better than glassy carbon electrode.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In this work, we investigate the effect of anti-site disorder on the half-metallic properties of a Mn 2 FeAl Heusler alloy thin film. The film was grown on TiN-buffered MgO 001 substrates via ...magnetron sputtering. A detailed structural characterization using x-ray diffraction (XRD) and anomalous XRD showed that the film crystallizes in the partially disordered L21B structure with 33% disorder between the Mn(B) and Al(D) sites. We measure a positive anisotropic magnetoresistance in the film, which is an indication of non-half metallic behaviour. Our x-ray magnetic circular dichroism sum rules analysis shows that Mn carries the magnetic moment in the film, with a positive Fe moment. Experimentally determined moments correspond most closely with those found by density functional calculated for the L21B structure with Mn(B) and Al(D) site disorder, matching the experimental structural analysis. We thus attribute the deviation from half-metallic behaviour to the formation of the L21B structure. To realize a half-metallic Mn2FeAl film it is important that the inverse Heusler XA structure is stabilized with minimal anti-site atomic disorder.
We report on the effect of the lateral confinement and a perpendicular magnetic field on isolated room-temperature magnetic skyrmions in sputtered Pt/Co/MgO nanotracks and nanodots. We show that the ...skyrmions size can be easily tuned by playing on the lateral dimensions of the nanostructures and by using external magnetic field amplitudes of a few mT, which allow to reach sub-100 nm diameters. Our XMCD-PEEM observations also highlight the important role of the pinning on the skyrmions size and stability under an out-of-plane magnetic field. Micromagnetic simulations reveal that the effect of local pinning can be well accounted for by considering the thin film grain structure with local anisotropy variations and reproduce well the dependence of the skyrmion diameter on the magnetic field and the geometry.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Emergent behaviors occur when simple interactions between a system's constituent elements produce properties that the individual elements do not exhibit in isolation. This article reports tunable ...emergent behaviors observed in domain wall (DW) populations of arrays of interconnected magnetic ring‐shaped nanowires under an applied rotating magnetic field. DWs interact stochastically at ring junctions to create mechanisms of DW population loss and gain. These combine to give a dynamic, field‐dependent equilibrium DW population that is a robust and emergent property of the array, despite highly varied local magnetic configurations. The magnetic ring arrays’ properties (e.g., non‐linear behavior, “fading memory” to changes in field, fabrication repeatability, and scalability) suggest they are an interesting candidate system for realizing reservoir computing (RC), a form of neuromorphic computing, in hardware. By way of example, simulations of ring arrays performing RC approaches 100% success in classifying spoken digits for single speakers.
Arrays of interconnected soft ferromagnetic nanorings contain mobile domain walls (DWs) that are driven around the rings by a rotating magnetic field. DWs have a probability of passing ring junctions, which leads to DW loss/gain mechanisms and, over the array, a stable DW equilibrium population. This emergent property is used to perform reservoir computing on a voice recognition task.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
Transition metal oxides are promising candidates for the next generation of spintronic devices due to their fascinating properties that can be effectively engineered by strain, defects, and ...microstructure. An excellent example can be found in ferroelastic LaCoO
3
with paramagnetism in bulk. In contrast, unexpected ferromagnetism is observed in tensile-strained LaCoO
3
films, however, its origin remains controversial. Here we simultaneously reveal the formation of ordered oxygen vacancies and previously unreported long-range suppression of CoO
6
octahedral rotations throughout LaCoO
3
films. Supported by density functional theory calculations, we find that the strong modification of Co 3
d
-O 2
p
hybridization associated with the increase of both Co-O-Co bond angle and Co-O bond length weakens the crystal-field splitting and facilitates an ordered high-spin state of Co ions, inducing an emergent ferromagnetic-insulating state. Our work provides unique insights into underlying mechanisms driving the ferromagnetic-insulating state in tensile-strained ferroelastic LaCoO
3
films while suggesting potential applications toward low-power spintronic devices.
Magnetic skyrmions are chiral spin textures which hold great promise as nanoscale information carriers. Their recent observation at room temperature and their fast current-induced manipulation in ...multiple repetitions of heavy metal/ferromagnetic stacks have lifted an important bottleneck towards the practical realisation of skyrmion-based devices. However, the complex spin textures and large power dissipation in these multilayers limit their practical implementation as well as the fundamental understanding of the skyrmion dynamics. Here, we report on the current-driven motion of skyrmions in an ultrathin Pt/Co/MgO model system. We find that skyrmions with diameters in the 100 nm range can move at speeds up to 100 m.s−1−1^{-1}. Our experiments also reveal that the skyrmion Hall effect is markedly drive-dependent. These observations are well substantiated both by a simple analytical model and micromagnetic simulations, which highlight the important role of pinning in the skyrmion dynamics.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
High‐resolution magnetoelectric imaging is used to demonstrate electrical control of the perpendicular local magnetization associated with 125 nm‐wide magnetic stripe domains in 100‐nm‐thick Ni ...films. This magnetoelectric coupling is achieved in zero magnetic field using strain from ferroelectric BaTiO3 substrates to control perpendicular anisotropy imposed by the growth stress. These findings may be exploited for perpendicular recording in nanopatterned hybrid media.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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