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1,334 results on '"Dunin-Borkowski, Rafal E."'

101. Operando high-pressure investigation of size-controlled CuZn catalysts for the methanol synthesis reaction

Author

Divins, Núria J., Kordus, David, Timoshenko, Janis, Sinev, Ilya, Zegkinoglou, Ioannis, Bergmann, Arno, Chee, See Wee, Widrinna, Simon, Karslıoğlu, Osman, Mistry, Hemma, Lopez Luna, Mauricio, Zhong, Jian Qiang, Hoffman, Adam S., Boubnov, Alexey, Boscoboinik, J. Anibal, Heggen, Marc, Dunin-Borkowski, Rafal E., Bare, Simon R., and Cuenya, Beatriz Roldan

Published
2021
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112. Element-Specific Study of Magnetic Anisotropy and Hardening in SmCo5–xCux Thin Films

Author

Gkouzia, Georgia, primary, Günzing, Damian, additional, Xie, Ruiwen, additional, Weßels, Teresa, additional, Kovács, András, additional, N’Diaye, Alpha T., additional, Major, Márton, additional, Palakkal, J. P., additional, Dunin-Borkowski, Rafal E., additional, Wende, Heiko, additional, Zhang, Hongbin, additional, Ollefs, Katharina, additional, and Alff, Lambert, additional

Published
2023
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117. Geometric reconstruction methods for electron tomography

Author

Alpers, Andreas, Gardner, Richard J., König, Stefan, Pennington, Robert S., Boothroyd, Chris B., Houben, Lothar, Dunin-Borkowski, Rafal E., and Batenburg, Kees Joost

Subjects
Mathematical Physics, Condensed Matter - Materials Science
Abstract

Electron tomography is becoming an increasingly important tool in materials science for studying the three-dimensional morphologies and chemical compositions of nanostructures. The image quality obtained by many current algorithms is seriously affected by the problems of missing wedge artefacts and nonlinear projection intensities due to diffraction effects. The former refers to the fact that data cannot be acquired over the full $180^\circ$ tilt range; the latter implies that for some orientations, crystalline structures can show strong contrast changes. To overcome these problems we introduce and discuss several algorithms from the mathematical fields of geometric and discrete tomography. The algorithms incorporate geometric prior knowledge (mainly convexity and homogeneity), which also in principle considerably reduces the number of tilt angles required. Results are discussed for the reconstruction of an InAs nanowire.

Published
2012
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118. Atomically Resolved Phase Coexistence in VO2Thin Films

Author

Ahmadi, Masoud, Atul, Atul, de Graaf, Sytze, van der Veer, Ewout, Meise, Ansgar, Tavabi, Amir Hossein, Heggen, Marc, Dunin-Borkowski, Rafal E., Ahmadi, Majid, and Kooi, Bart J.

Abstract

Concurrent structural and electronic transformations in VO2thin films are of 2-fold importance: enabling fine-tuning of the emergent electrical properties in functional devices, yet creating an intricate interfacial domain structure of transitional phases. Despite the importance of understanding the structure of VO2thin films, a detailed real-space atomic structure analysis in which the oxygen atomic columns are also resolved is lacking. Moreover, intermediate atomic structures have remained elusive due to the lack of robust atomically resolved quantitative analysis. Here, we directly resolve both V and O atomic columns and discover the presence of intermediate monoclinic (M2) phase nanolayers (less than 2 nm thick) in epitaxially grown VO2films on a TiO2(001) substrate, where the dominant part of VO2undergoes a transition from the tetragonal (rutile) phase to the monoclinic M1 phase. Strain analysis suggests that the presence of the M2 phase is related to local strain gradients near the TiO2/VO2interface. We unfold the crucial role of imaging the spatial configurations of the oxygen anions (in addition to V cations) by utilizing atomic-resolution electron microscopy. Our approach can be used to unravel the structural transitions in a wide range of correlated oxides, offering substantial implications for, e.g., optoelectronics and ferroelectrics.

Published
2024
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119. Formation process and superparamagnetic properties of (Mn,Ga)As nanocrystals in GaAs fabricated by annealing of (Ga,Mn)As layers with low Mn content

Author

Sadowski, Janusz, Domagala, Jaroslaw Z., Mathieu, Roland, Kovacs, Andras, Kasama, Takeshi, Dunin-Borkowski, Rafal E., and Dietl, Tomasz

Subjects
Condensed Matter - Materials Science
Abstract

X-ray diffraction, transmission electron microscopy, and magnetization measurements are employed to study the structural and magnetic properties of Mn-rich (Mn,Ga)As nanocrystals embedded in GaAs. These nanocomposites are obtained by moderate (400C) and high temperature (560 and 630C) annealing of (Ga,Mn)As layers with Mn concentrations between 0.1 and 2%, grown by molecular beam epitaxy at 270oC. Decomposition of (Ga,Mn)As is already observed at the lowest annealing temperature of 400C for layers with initial Mn content of 1% and 2%. Both cubic and hexagonal (Mn,Ga)As nanocrystals, with similar diameters of 7 - 10 nm are observed to coexist in layers with an initial Mn content of 0.5% after higher temperature annealing. Measurements of magnetization relaxation in the time span 0.1 - 10 000 s provide evidence for superparamagnetic properties of the (Mn,Ga)As nanocrystals, as well as for the absence of spin-glass dynamics. These findings point to weak coupling between nanocrystals even in layers with the highest nanocrystal density., Comment: 24 pages, 7 figures

Published
2011
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121. Live Iterative Ptychography.

Author

Weber, Dieter, Ehrig, Simeon, Schropp, Andreas, Clausen, Alexander, Achilles, Silvio, Hoffmann, Nico, Bussmann, Michael, Dunin-Borkowski, Rafal E, and Schroer, Christian G

Published
2024
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123. Neutron-activated, plasmonically excitable Fe-Pt-Yb2O3 nanoparticles delivering anti-cancer radiation against human glioblastoma brain cancer cells

Author

Seemann, Klaus M., primary, Kovács, András, additional, Schmid, Thomas E., additional, Ilicic, Katarina, additional, Multhoff, Gabriele, additional, Dunin-Borkowski, Rafal E., additional, Michelagnoli, Caterina, additional, Cieplicka-Oryńczak, Natalia, additional, Jana, Soumen, additional, Colombi, Giacomo, additional, Jentschel, Michael, additional, Schneider, Claus M., additional, and Kuhn, Bernd, additional

Published
2023
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124. Large Interfacial Rashba Interaction Generating Strong Spin–Orbit Torques in Atomically Thin Metallic Heterostructures

Author

Krishnia, Sachin, primary, Sassi, Yanis, additional, Ajejas, Fernando, additional, Sebe, Nicolas, additional, Reyren, Nicolas, additional, Collin, Sophie, additional, Denneulin, Thibaud, additional, Kovács, András, additional, Dunin-Borkowski, Rafal E., additional, Fert, Albert, additional, George, Jean-Marie, additional, Cros, Vincent, additional, and Jaffrès, Henri, additional

Published
2023
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126. Towards Three-dimensional Mapping of Skyrmionic Spin Textures in an FeGe Nanodisk Using Off-axis Electron Holography

Author

Zheng, Fengshan, primary, Caron, Jan, additional, Savchenko, Andrii S, additional, Wang, Shasha, additional, Wang, Weiwei, additional, Denneulin, Thibaud, additional, Kovács, András, additional, Du, Hongchu, additional, Du, Haifeng, additional, Kiselev, Nikolai S, additional, Blügel, Stefan, additional, and Dunin-Borkowski, Rafal E, additional

Published
2023
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128. One-Dimensional “Ghost Imaging” in Electron Microscopy of Inelastically Scattered Electrons

Author

Rotunno, Enzo, primary, Gargiulo, Simone, additional, Vanacore, Giovanni M., additional, Mechel, Chen, additional, Tavabi, Amir H., additional, Dunin-Borkowski, Rafal E., additional, Carbone, Fabrizio, additional, Madan, Ivan, additional, Frabboni, Stefano, additional, Guner, Tugrul, additional, Karimi, Ebrahim, additional, Kaminer, Ido, additional, and Grillo, Vincenzo, additional

Published
2023
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134. Theoretical and practical aspects of the design and production of synthetic holograms for transmission electron microscopy.

Author

Rosi, Paolo, Venturi, Federico, Medici, Giacomo, Menozzi, Claudia, Gazzadi, Gian Carlo, Rotunno, Enzo, Frabboni, Stefano, Balboni, Roberto, Rezaee, Mohammadreza, Tavabi, Amir H., Dunin-Borkowski, Rafal E., Karimi, Ebrahim, and Grillo, Vincenzo

Subjects
FREE electron lasers, TRANSMISSION electron microscopy, HOLOGRAPHY, SPATIAL light modulators, VORTEX generators, QUANTUM mechanics
Abstract

Beam shaping—the ability to engineer the phase and the amplitude of massive and massless particles—has long interested scientists working on communication, imaging, and the foundations of quantum mechanics. In light optics, the shaping of electromagnetic waves (photons) can be achieved using techniques that include, but are not limited to, direct manipulation of the beam source (as in x-ray free electron lasers and synchrotrons), deformable mirrors, spatial light modulators, mode converters, and holograms. The recent introduction of holographic masks for electrons provides new possibilities for electron beam shaping. Their fabrication has been made possible by advances in micrometric and nanometric device production using lithography and focused on ion beam patterning. This article provides a tutorial on the generation, production, and analysis of synthetic holograms for transmission electron microscopy. It begins with an introduction to synthetic holograms, outlining why they are useful for beam shaping to study material properties. It then focuses on the fabrication of the required devices from theoretical and experimental perspectives, with examples taken from both simulations and experimental results. Applications of synthetic electron holograms as aberration correctors, electron vortex generators, and spatial mode sorters are then presented. [ABSTRACT FROM AUTHOR]

Published
2022
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136. Post-Synthesis Heat Treatment of Doped PtNi-Alloy Fuel-Cell Catalyst Nanoparticles Studied by In-Situ Electron Microscopy

Author

MacArthur, Katherine E., primary, Polani, Shlomi, additional, Klingenhof, Malte, additional, Gumbiowski, Nina, additional, Möller, Tim, additional, Paciok, Paul, additional, Kang, Jiaqi, additional, Epple, Matthias, additional, Basak, Shibabrata, additional, Eichel, Rüdiger-A., additional, Strasser, Peter, additional, Dunin-Borkowski, Rafal E., additional, and Heggen, Marc, additional

Published
2023
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139. Large interfacial Rashba interaction and resultant dominating field- like torque in atomically thin metallic heterostructures

Author

Krishnia, Sachin, primary, Sebe, Nicolas, additional, Sassi, Yanis, additional, Ajejas, Fernando, additional, Reyren, Nicolas, additional, Collin, Sophie, additional, Denneulin, Thibaud, additional, Kovács, András, additional, Dunin-Borkowski, Rafal E., additional, Fert, Albert, additional, George, Jean-Marie, additional, Jaffres, Henri, additional, and Cros, Vincent, additional

Published
2023
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144. Magnetite Morphology and Life on Mars

Author

Buseck, Peter R., Dunin-Borkowski, Rafal E., Devouard, Bertrand, Frankel, Richard B., McCartney, Martha R., Midgley, Paul A., Pósfai, Mihály, and Weyland, Matthew

Published
2001

150. Focused ion beam fabrication of Janus bimetallic cylinders acting as drift tube Zernike phase plates for electron microscopy.

Author

Rosi, Paolo, Gazzadi, Gian Carlo, Frabboni, Stefano, Grillo, Vincenzo, Tavabi, Amir H., Dunin-Borkowski, Rafal E., and Pozzi, Giulio

Subjects
FOCUSED ion beams, JANUS particles, ELECTRON microscopy, AHARONOV-Bohm effect, ELECTRON beams, TUBES
Abstract

Modern nanotechnology techniques offer new opportunities for fabricating structures and devices at the micrometer and sub-micrometer level. Here, we use focused ion beam techniques to realize micrometer-sized Janus bimetallic cylinders acting as drift tube devices, which are able to impart a controlled phase shift to an electron wave. The phase shift results from the presence of contact potentials in the cylinders, in a similar manner to the electrostatic Aharonov–Bohm effect in bimetallic wires. We use electron Fraunhofer interference to demonstrate that such bimetallic structures introduce phase shifts that can be tuned to desired values by varying the dimensions of the pillars, in particular their heights. Such devices are promising for electron beam shaping and for the realization of electrostatic Zernike phase plates (i.e., devices that are able to impart a constant phase shift between an unscattered and a scattered electron wave) in electron microscopy, in particular, cryo-electron microscopy. [ABSTRACT FROM AUTHOR]

Published
2021
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