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34 results on '"Bykova, Iuliia"'

1. Freezing and thawing magnetic droplet solitons

Author

Ahlberg, Martina, Chung, Sunjae, Jiang, Sheng, Le, Q. Tuan, Khymyn, Roman, Mazraati, Hamid, Weigand, Markus, Bykova, Iuliia, Groß, Felix, Goering, Eberhard, Schütz, Gisela, Gräfe, Joachim, and Åkerman, Johan

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Magnetic droplets are non-topological magnetodynamical solitons displaying a wide range of complex dynamic phenomena with potential for microwave signal generation. Bubbles, on the other hand, are internally static cylindrical magnetic domains, stabilized by external fields and magnetostatic interactions. In its original theory, the droplet was described as an imminently collapsing bubble stabilized by spin transfer torque and, in its zero-frequency limit, as equivalent to a bubble. Without nanoscale lateral confinement, pinning, or an external applied field, such a nanobubble is unstable, and should collapse. Here, we show that we can freeze dynamic droplets into static nanobubbles by decreasing the magnetic field. While the bubble has virtually the same resistance as the droplet, all signs of low-frequency microwave noise disappear. The transition is fully reversible and the bubble can be thawed back into a droplet if the magnetic field is increased under current. Whereas the droplet collapses without a sustaining current, the bubble is highly stable and remains intact for days without external drive. Electrical measurements are complemented by direct observation using scanning transmission x-ray microscopy, which corroborates the analysis and confirms that the bubble is stabilized by pinning., Comment: 23 pages, 5 figures

Published
2021
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2. X‑ray Microspectroscopy and Ptychography on Nanoscale Structures in Rock Varnish

Author

Förster, Jan-David, Bykova, Iuliia, Macholdt, Dorothea S, Jochum, Klaus Peter, Kappl, Michael, Kilcoyne, AL David, Müller, Maren, Sorowka, Antje, Weber, Bettina, Weigand, Markus, Schütz, Gisela, Andreae, Meinrat O, and Pöhlker, Christopher

Subjects
Chemical Sciences, Engineering, Technology, Physical Chemistry
Abstract

X-ray microspectroscopy is a powerful analytical method in geoscientific and environmental research as it provides a unique combination of nanoscale imaging with high spectroscopic sensitivity at relatively low beam-related sample damage. In this study, "classical"scanning transmission soft X-ray microscopy (STXM) with X-ray absorption spectroscopy and the recently established soft X-ray ptychography are applied to the analysis of selected rock varnish samples from urban and arid desert environments. X-ray ptychography enhances the spatial resolution relative to STXM by up to 1 order of magnitude. With its high chemical sensitivity, it can resolve nanoscale differences in valence states of the key varnish elements manganese (Mn) and iron. Our results emphasize the complex nanoarchitecture of rock varnish as well as the diverse mineralogy of the Mn oxy-hydroxide matrix and its embedded dust grains. In contrast to the fast-growing urban varnish, the slow-growing arid desert varnish revealed a remarkable nanoscale stratification of alternating Mn valence states, providing hints on the layer-wise and still enigmatic growth process.

Published
2021

3. Magnons in a Quasicrystal: Propagation, Localization and Extinction of Spin Waves in Fibonacci Structures

Author

Lisiecki, Filip, Rychły, Justyna, Kuświk, Piotr, Głowiński, Hubert, Kłos, Jarosław W., Groß, Felix, Bykova, Iuliia, Weigand, Markus, Zelent, Mateusz, Goering, Eberhard, Schütz, Gisela, Krawczyk, Maciej, Stobiecki, Feliks, Dubowik, Janusz, and Gräfe, Joachim

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Magnonic quasicrystals exceed the possibilities of spin wave (SW) manipulation offered by regular magnonic crystals, because of their more complex SW spectra with fractal characteristics. Here, we report the direct x-ray microscopic observation of propagating SWs in a magnonic quasicrystal, consisting of dipolarly coupled permalloy nanowires arranged in a one-dimensional Fibonacci sequence. SWs from the first and second band as well as evanescent waves from the band gap between them are imaged. Moreover, additional mini-band gaps in the spectrum are demonstrated, directly indicating an influence of the quasiperiodicity of the system. The experimental results are interpreted using numerical calculations and we deduce a simple model to estimate the frequency position of the magnonic gaps in quasiperiodic structures. The demonstrated features of SW spectra in one-dimensional magnonic quasicrystals allows utilizing this class of metamaterials for magnonics and makes them an ideal basis for future applications., Comment: 10 pages, 6 figures

Published
2018
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4. Direct observation of magnetic droplet solitons in all-perpendicular spin torque nano-oscillators

Author

Chung, Sunjae, Le, Q. Tuan, Ahlberg, Martina, Weigand, Markus, Bykova, Iuliia, Awad, Ahmad A., Mazraati, Hamid, Houshang, Afshin, Jiang, Sheng, Nguyen, T. N. Anh, Goering, Eberhard, Schütz, Gisela, Gräfe, Joachim, and Åkerman, Johan

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Magnetic droplets are non-topological dynamical solitons that can be nucleated and sustained in nano-contact based spin torque nano-oscillators (NC-STNOs) with perpendicular anisotropy free layers. While originally predicted in all-perpendicular NC-STNOs, all experimental demonstrations have so far relied on orthogonal devices with an in-plane polarizing layer that requires a strong magnetic field for droplet nucleation. Here, we instead show the nucleation and sustained operation of magnetic droplets in all-perpendicular NC-STNOs in modest perpendicular fields and over a wide range of nano-contact size. The droplet is observed electrically as an intermediate resistance state accompanied by broadband low-frequency microwave noise. Using canted fields, which introduce a non-zero relative angle between the free and fixed layer, the actual droplet precession frequency can also be determined. Finally, the droplet size, its perimeter width, and its fully reversed core are directly observed underneath a 80 nm diameter nano-contact using scanning transmission x-ray microscopy on both the Ni and Co edges. The droplet diameter is 150 nm, i.e. almost twice the nominal size of the nano-contact, and the droplet has a perimeter width of about 70 nm.

Published
2017

5. Freezing and thawing magnetic droplet solitons

Author

Ahlberg, Martina, Chung, Sunjae, Jiang, Sheng, Frisk, Andreas, Khademi, Maha, Khymyn, Roman, Awad, Ahmad A., Le, Q. Tuan, Mazraati, Hamid, Mohseni, Majid, Weigand, Markus, Bykova, Iuliia, Groß, Felix, Goering, Eberhard, Schütz, Gisela, Gräfe, Joachim, and Åkerman, Johan

Published
2022
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6. Skyrmion Hall Effect Revealed by Direct Time-Resolved X-Ray Microscopy

Author

Litzius, Kai, Lemesh, Ivan, Krüger, Benjamin, Bassirian, Pedram, Caretta, Lucas, Richter, Kornel, Büttner, Felix, Sato, Koji, Tretiakov, Oleg A., Förster, Johannes, Reeve, Robert M., Weigand, Markus, Bykova, Iuliia, Stoll, Hermann, Schütz, Gisela, Beach, Geoffrey S. D., and Kläui, Mathias

Subjects
Condensed Matter - Materials Science
Abstract

Magnetic skyrmions are highly promising candidates for future spintronic applications such as skyrmion racetrack memories and logic devices. They exhibit exotic and complex dynamics governed by topology and are less influenced by defects, such as edge roughness, than conventionally used domain walls. In particular, their finite topological charge leads to a predicted "skyrmion Hall effect", in which current-driven skyrmions acquire a transverse velocity component analogous to charged particles in the conventional Hall effect. Here, we present nanoscale pump-probe imaging that for the first time reveals the real-time dynamics of skyrmions driven by current-induced spin orbit torque (SOT). We find that skyrmions move at a well-defined angle {\Theta}_{SH} that can exceed 30{\deg} with respect to the current flow, but in contrast to theoretical expectations, {\Theta}_{SH} increases linearly with velocity up to at least 100 m/s. We explain our observation based on internal mode excitations in combination with a field-like SOT, showing that one must go beyond the usual rigid skyrmion description to unravel the dynamics., Comment: pdf document arxiv_v1.1. 24 pages (incl. 9 figures and supplementary information)

Published
2016
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7. High-resolution ptychographic imaging at a seeded free-electron laser source using OAM beams

Author

Pancaldi, Matteo, Guzzi, Francesco, Bevis, Charles S., Manfredda, Michele, Barolak, Jonathan, Bonetti, Stefano, Bykova, Iuliia, De Angelis, Dario, De Ninno, Giovanni, Fanciulli, Mauro, Novinec, Luka, Pedersoli, Emanuele, Ravindran, Arun, Rösner, Benedikt, David, Christian, Ruchon, Thierry, Simoncig, Alberto, Zangrando, Marco, Adams, Daniel E., Vavassori, Paolo, Sacchi, Maurizio, Kourousias, George, Mancini, Giulia F., Capotondi, Flavio, Pancaldi, Matteo, Guzzi, Francesco, Bevis, Charles S., Manfredda, Michele, Barolak, Jonathan, Bonetti, Stefano, Bykova, Iuliia, De Angelis, Dario, De Ninno, Giovanni, Fanciulli, Mauro, Novinec, Luka, Pedersoli, Emanuele, Ravindran, Arun, Rösner, Benedikt, David, Christian, Ruchon, Thierry, Simoncig, Alberto, Zangrando, Marco, Adams, Daniel E., Vavassori, Paolo, Sacchi, Maurizio, Kourousias, George, Mancini, Giulia F., and Capotondi, Flavio

Abstract

Electromagnetic waves possessing orbital angular momentum (OAM) are powerful tools for applications in optical communications, quantum technologies, and optical tweezers. Recently, they have attracted growing interest since they can be harnessed to detect peculiar helical dichroic effects in chiral molecular media and in magnetic nanostructures. In this work, we perform single-shot per position ptychography on a nanostructured object at a seeded free-electron laser, using extreme ultraviolet OAM beams of different topological charge orders ℓ generated with spiral zone plates. By controlling ℓ, we demonstrate how the structural features of OAM beam profiles determine an improvement of about 30% in image resolution with respect to conventional Gaussian beam illumination. This result extends the capabilities of coherent diffraction imaging techniques, and paves the way for achieving time-resolved high-resolution (below 100 nm) microscopy on large area samples.

Published
2024
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8. Transient X‐Ray Absorption Near Edge Structure Spectroscopy Using Broadband Free‐Electron Laser Pulses.

Author

Juranić, Pavle, Cirelli, Claudio, Mamyrbayev, Talgat, Uemura, Yohei, Vila‐Comamala, Joan, Lima, Frederico Alves, Bacellar, Camila, Johnson, Philip J. M., Prat, Eduard, Reiche, Sven, Wach, Anna, Bykova, Iuliia, Kahraman, Abdullah, Kabanova, Victoria, Milne, Christopher, and David, Christian

Subjects
OXALATES, X-ray absorption near edge structure, ACQUISITION of data, SPECTROMETRY, BANDWIDTHS, FREE electron lasers, ABSORPTION, LASER pulses
Abstract

A new method for time‐resolved X‐ray absorption near edge structure (XANES) spectroscopy that enables faster data acquisition and requires smaller sample quantities for high‐quality data, thus allowing the analysis of more samples in a shorter time is introduced. The method uses large bandwidth free electron laser pulses to measure laser‐excited XANES spectra in transmission mode. A beam‐splitting grating configuration allows simultaneous measurements of the spectra of the incoming X‐ray Free Electron Laser (XFEL) pulses and transmission XANES, which is crucial for compensating the pulse‐dependent intensity and spectrum fluctuations due to the self‐amplified spontaneous emission operation. The implementation of this new methodology is applied on a liquid solution of ammonium iron(III) oxalate jet and is compared to previous results, showing great improvements in the speed of acquisition and spectral resolution, and the ability to measure a large 2‐D spectral‐time map quickly. [ABSTRACT FROM AUTHOR]

Published
2024
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9. High-resolution ptychographic imaging at a seeded free-electron laser source using OAM beams

Author

Pancaldi, Matteo, primary, Guzzi, Francesco, additional, Bevis, Charles S., additional, Manfredda, Michele, additional, Barolak, Jonathan, additional, Bonetti, Stefano, additional, Bykova, Iuliia, additional, De Angelis, Dario, additional, De Ninno, Giovanni, additional, Fanciulli, Mauro, additional, Novinec, Luka, additional, Pedersoli, Emanuele, additional, Ravindran, Arun, additional, Rösner, Benedikt, additional, David, Christian, additional, Ruchon, Thierry, additional, Simoncig, Alberto, additional, Zangrando, Marco, additional, Adams, Daniel E., additional, Vavassori, Paolo, additional, Sacchi, Maurizio, additional, Kourousias, George, additional, Mancini, Giulia F., additional, and Capotondi, Flavio, additional

Published
2024
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11. P‐107: High‐Resolution Periodic Patterning for Volume Manufacturing on +300mm Size Substrates Using Displacement Talbot Lithography.

Author

Wooley, Kelsey, Solak, Harun, Dais, Christian, Clube, Francis, Mohammad, Ahmed, Bykova, Iuliia, Lebugle, Maxime, Seure, Thibault, Heydari, Mehdi, Wilson, Matthew, and Wang, Li

Subjects
DISTRIBUTED feedback lasers, BIOCHEMICAL substrates, LITHOGRAPHY, PRODUCTION quantity, SHOOTING (Sports)
Abstract

The photonic device market has a need for low‐cost, high‐resolution periodic patterning that scales with product maturity to large substrate sizes. Eulitha's DTL (Displacement Talbot Lithography) technology was limited to only a single exposure field per substrate on preexisting platforms which can fully pattern 100 and 150mm substrates. The new 'PhableS' is Eulitha's step‐and‐repeat solution to bring all the advantages of the DTL patterning to larger substrates. The PhableS tool builds on Eulitha's patented displacement Talbot lithography technology to open the way for customers to fully scale to high volume production. This tool retains the strong technical performance; including 60nm half pitch resolution (DUV version), 140x140mm2 single shot exposure field, large depth of focus (hundreds of microns), high throughput (+40wph), non‐contact, mask‐based patterning. Automated wafer and mask handling support industry expected repeatability and defect‐free patterning. [ABSTRACT FROM AUTHOR]

Published
2024
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13. The Journal of Physical Chemistry C / X‑ray Microspectroscopy and Ptychography on Nanoscale Structures in Rock Varnish

Author

Förster, Jan-David, Förster, Jan-David, Bykova, Iuliia, Macholdt, Dorothea S., Jochum, Klaus Peter, Kappl, Michael, Kilcoyne, A. L. David, Müller, Maren, Sorowka, Antje, Weber, Bettina, Weigand, Markus, Schütz, Gisela, Andreae, Meinrat O., Pöhlker, Christopher, Förster, Jan-David, Förster, Jan-David, Bykova, Iuliia, Macholdt, Dorothea S., Jochum, Klaus Peter, Kappl, Michael, Kilcoyne, A. L. David, Müller, Maren, Sorowka, Antje, Weber, Bettina, Weigand, Markus, Schütz, Gisela, Andreae, Meinrat O., and Pöhlker, Christopher

Abstract

X-ray microspectroscopy is a powerful analytical method in geoscientific and environmental research as it provides a unique combination of nanoscale imaging with high spectroscopic sensitivity at relatively low beam-related sample damage. In this study, “classical” scanning transmission soft X-ray microscopy (STXM) with X-ray absorption spectroscopy and the recently established soft X-ray ptychography are applied to the analysis of selected rock varnish samples from urban and arid desert environments. X-ray ptychography enhances the spatial resolution relative to STXM by up to 1 order of magnitude. With its high chemical sensitivity, it can resolve nanoscale differences in valence states of the key varnish elements manganese (Mn) and iron. Our results emphasize the complex nanoarchitecture of rock varnish as well as the diverse mineralogy of the Mn oxy–hydroxide matrix and its embedded dust grains. In contrast to the fast-growing urban varnish, the slow-growing arid desert varnish revealed a remarkable nanoscale stratification of alternating Mn valence states, providing hints on the layer-wise and still enigmatic growth process., Version of record

Published
2021
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14. Freezing and thawing magnetic droplet solitons

Author

Ahlberg, M., primary, Chung, Sunjae, additional, Jiang, Sheng, additional, Le, Q. Tuan, additional, Khymyn, Roman, additional, Mazraati, Hamid, additional, Weigand, Markus, additional, Bykova, Iuliia, additional, Groß, Felix, additional, Goering, Eberhard, additional, Schütz, Gisela, additional, Gräfe, Joachim, additional, and Åkerman, Johan, additional

Published
2021
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15. Ptychographic imaging and micromagnetic modeling of thermal melting of nanoscale magnetic domains in antidot lattices

Author

Gräfe, Joachim, primary, Skripnik, Maxim, additional, Dieterle, Georg, additional, Haering, Felix, additional, Weigand, Markus, additional, Bykova, Iuliia, additional, Träger, Nick, additional, Stoll, Hermann, additional, Tyliszczak, Tolek, additional, Vine, David, additional, Ziemann, Paul, additional, Wiedwald, Ulf, additional, Shapiro, David, additional, Nowak, Ulrich, additional, Schütz, Gisela, additional, and Goering, Eberhard J., additional

Published
2020
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19. High-resolution X-ray ptychography for magnetic imaging

Author

Bykova, Iuliia and Schütz, Gisela (Prof. Dr.)

Abstract

The resolution in standard X-ray microscopes is limited by the focusing element, e.g. Fresnel Zone Plates (FZP), and stays in the range of 20 nm for highly efficient plates. Diffraction imaging techniques with the use of coherent X-ray radiation potentially can achieve wavelength limited resolution solving so-called “phase problem”. Ptychography is the combination of diffraction imaging and scanning transmission microscopy that provides images of extended sample areas utilizing iterative reconstruction algorithm. The main focus of this thesis is the realization of ptychographic imaging on the samples with different scattering power, as well as the investigation and improvement of the microscopic potential of this method in detailed comparison with conventional STXM imaging. The technique is applied to sub-100 nm sized magnetic structures of the current scientific interest, i.e. domain walls, vortices and skyrmions.

Published
2018
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20. Energy-efficient construction in the climatic conditions of Latvia

Author

Borodinecs, Anatolijs, Zemitis, Jurgis, Geikins, Aleksandrs, Bykova, Iuliia, and Nefedova, Anna

Subjects
insulation, ограждающие конструкции, zero energy house, инсоляция, климат, Латвия, энергоэффективное строительство, climate, Latvia, feasibility
Abstract

The low energy building can be achieved by implementation of energy efficient building envelope as well as energy efficient heating and ventilation systems. In addition use of renewable energy sources allows reach nZEB and ZEB requirements. This paper provides calculation approach and conclusions on necessary insulation thickness for opaque elements. In addition optimal windows sizes, their orientation and thermal properties to achieve low energy buildings standards in Latvian climate is evaluated in this study. This has been done for single family house. Study takes into account specifics of low energy consumption buildings for five largest cities of Latvia located at places with maximally diverse climatic conditions. The paper presents economical and payback time calculations of low energy building constructions and HVAC systems in Latvia., Низкое энергопотребление может быть достигнуто за счет внедрения энергоэффективных ограждающих конструкций, а также энергоэффективных систем отопления и вентиляции. Кроме того, использование возобновляемых источников энергии позволяет достичь требований nZEB и ZEB. В этой статье дается расчетный подход и выводы о необходимой толщине изоляции для непрозрачных элементов. Кроме того, в этом исследовании оцениваются оптимальные размеры окон, их ориентация и тепловые свойства для достижения стандартов низкоэнергетических зданий в латвийском климате. Расчеты были проведены для жилого дома для одной семьи. В исследовании учтены особенности зданий с низким потреблением энергии для пяти крупнейших городов Латвии, расположенных в местах с максимально разнообразными климатическими условиями. В статье представлены расчеты экономичности и окупаемости низкоэнергетических строительных конструкций и систем ОВК в Латвии.

Published
2018
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21. Magnons in a Quasicrystal: Propagation, Extinction, and Localization of Spin Waves in Fibonacci Structures

Author

Lisiecki, Filip, primary, Rychły, Justyna, additional, Kuświk, Piotr, additional, Głowiński, Hubert, additional, Kłos, Jarosław W., additional, Groß, Felix, additional, Träger, Nick, additional, Bykova, Iuliia, additional, Weigand, Markus, additional, Zelent, Mateusz, additional, Goering, Eberhard J., additional, Schütz, Gislea, additional, Krawczyk, Maciej, additional, Stobiecki, Feliks, additional, Dubowik, Janusz, additional, and Gräfe, Joachim, additional

Published
2019
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22. Reprogrammability and Scalability of Magnonic Fibonacci Quasicrystals

Author

Lisiecki, Filip, primary, Rychły, Justyna, additional, Kuświk, Piotr, additional, Głowiński, Hubert, additional, Kłos, Jarosław W., additional, Groß, Felix, additional, Bykova, Iuliia, additional, Weigand, Markus, additional, Zelent, Mateusz, additional, Goering, Eberhard J., additional, Schütz, Gisela, additional, Gubbiotti, Gianluca, additional, Krawczyk, Maciej, additional, Stobiecki, Feliks, additional, Dubowik, Janusz, additional, and Gräfe, Joachim, additional

Published
2019
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23. Anatomy of Skyrmionic Textures in Magnetic Multilayers

Author

Li, Wenjing, primary, Bykova, Iuliia, additional, Zhang, Shilei, additional, Yu, Guoqiang, additional, Tomasello, Riccardo, additional, Carpentieri, Mario, additional, Liu, Yizhou, additional, Guang, Yao, additional, Gräfe, Joachim, additional, Weigand, Markus, additional, Burn, David M., additional, der Laan, Gerrit, additional, Hesjedal, Thorsten, additional, Yan, Zhengren, additional, Feng, Jiafeng, additional, Wan, Caihua, additional, Wei, Jinwu, additional, Wang, Xiao, additional, Zhang, Xiaomin, additional, Xu, Hongjun, additional, Guo, Chenyang, additional, Wei, Hongxiang, additional, Finocchio, Giovanni, additional, Han, Xiufeng, additional, and Schütz, Gisela, additional

Published
2019
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24. Direct Observation of Zhang-Li Torque Expansion of Magnetic Droplet Solitons

Author

Chung, Sunjae, Le, Q. Tuan, Ahlberg, Martina, Awad, Ahmad A., Weigand, Markus, Bykova, Iuliia, Khymyn, Roman, Dvornik, Mykola, Mazraati, Hamid, Houshang, Afshin, Jiang, Sheng, Anh Nguyen, T. N., Goering, Eberhard, Schuetz, Gisela, Gräfe, Joachim, Åkerman, Johan, Chung, Sunjae, Le, Q. Tuan, Ahlberg, Martina, Awad, Ahmad A., Weigand, Markus, Bykova, Iuliia, Khymyn, Roman, Dvornik, Mykola, Mazraati, Hamid, Houshang, Afshin, Jiang, Sheng, Anh Nguyen, T. N., Goering, Eberhard, Schuetz, Gisela, Gräfe, Joachim, and Åkerman, Johan

Abstract

Magnetic droplets are nontopological dynamical soli tons that can be nucleated in nanocontact based spin torque nano-oscillators (STNOs) with perpendicular magnetic anisotropy free layers. While theory predicts that the droplet should be of the same size as the nanocontact, its inherent drift instability has thwarted attempts at observing it directly using microscopy techniques. Here, we demonstrate highly stable magnetic droplets in all-perpendicular STNOs and present the first detailed droplet images using scanning transmission X-ray microscopy. In contrast to theoretical predictions, we find that the droplet diameter is about twice as large as the nanocontact. By extending the original droplet theory to properly account for the lateral current spread underneath the nanocontact, we show that the large discrepancy primarily arises from current-in-plane Zhang-Li torque adding an outward pressure on the droplet perimeter. Electrical measurements on droplets nucleated using a reversed current in the antiparallel state corroborate this picture.

Published
2018
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25. X-Ray Optics: 3D Nanofabrication of High-Resolution Multilayer Fresnel Zone Plates (Adv. Sci. 9/2018)

Author

Sanli, Umut Tunca, primary, Jiao, Chengge, additional, Baluktsian, Margarita, additional, Grévent, Corinne, additional, Hahn, Kersten, additional, Wang, Yi, additional, Srot, Vesna, additional, Richter, Gunther, additional, Bykova, Iuliia, additional, Weigand, Markus, additional, Schütz, Gisela, additional, and Keskinbora, Kahraman, additional

Published
2018
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27. New Concepts for 3D Optics in X-ray Microscopy

Author

Sanli, Umut Tunca, primary, Ceylan, Hakan, additional, Jiao, Chengge, additional, Baluktsian, Margarita, additional, Grevent, Corinne, additional, Hahn, Kersten, additional, Wang, Yi, additional, Srot, Vesna, additional, Richter, Gunther, additional, Bykova, Iuliia, additional, Weigand, Markus, additional, Sitti, Metin, additional, Schütz, Gisela, additional, and Keskinbora, Kahraman, additional

Published
2018
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30. 3D Nanofabrication of High-Resolution Multilayer Fresnel Zone Plates

Author

Sanli, Umut Tunca, primary, Jiao, Chengge, additional, Baluktsian, Margarita, additional, Grévent, Corinne, additional, Hahn, Kersten, additional, Wang, Yi, additional, Srot, Vesna, additional, Richter, Gunther, additional, Bykova, Iuliia, additional, Weigand, Markus, additional, Schütz, Gisela, additional, and Keskinbora, Kahraman, additional

Published
2018
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31. Direct Observation of Zhang-Li Torque Expansion of Magnetic Droplet Solitons

Author

Chung, Sunjae, primary, Le, Q. Tuan, additional, Ahlberg, Martina, additional, Awad, Ahmad A., additional, Weigand, Markus, additional, Bykova, Iuliia, additional, Khymyn, Roman, additional, Dvornik, Mykola, additional, Mazraati, Hamid, additional, Houshang, Afshin, additional, Jiang, Sheng, additional, Nguyen, T. N. Anh, additional, Goering, Eberhard, additional, Schütz, Gisela, additional, Gräfe, Joachim, additional, and Åkerman, Johan, additional

Published
2018
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32. Skyrmion Hall effect revealed by direct time-resolved X-ray microscopy

Author

Litzius, Kai, primary, Lemesh, Ivan, additional, Krüger, Benjamin, additional, Bassirian, Pedram, additional, Caretta, Lucas, additional, Richter, Kornel, additional, Büttner, Felix, additional, Sato, Koji, additional, Tretiakov, Oleg A., additional, Förster, Johannes, additional, Reeve, Robert M., additional, Weigand, Markus, additional, Bykova, Iuliia, additional, Stoll, Hermann, additional, Schütz, Gisela, additional, Beach, Geoffrey S. D., additional, and Kläui, Mathias, additional

Published
2016
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33. Skyrmion Hall effect revealed by direct time-resolved X-ray microscopy

Author

Litzius, Kai, Lemesh, Ivan, Krüger, Benjamin, Bassirian, Pedram, Caretta, Lucas, Richter, Kornel, Büttner, Felix, Sato, Koji, Tretiakov, Oleg A., Förster, Johannes, Reeve, Robert M., Weigand, Markus, Bykova, Iuliia, Stoll, Hermann, Schütz, Gisela, Beach, Geoffrey S. D., and Kläui, Mathias

Abstract

Magnetic skyrmions are promising candidates for future spintronic applications such as skyrmion racetrack memories and logic devices. They exhibit exotic and complex dynamics governed by topology and are less influenced by defects, such as edge roughness, than conventionally used domain walls. In particular, their non-zero topological charge leads to a predicted ‘skyrmion Hall effect’, in which current-driven skyrmions acquire a transverse velocity component analogous to charged particles in the conventional Hall effect. Here, we use nanoscale pump–probe imaging to reveal the real-time dynamics of skyrmions driven by current-induced spin–orbit torques. We find that skyrmions move at a well-defined angle ΘSkHthat can exceed 30° with respect to the current flow, but in contrast to conventional theoretical expectations, ΘSkHincreases linearly with velocity up to at least 100 ms−1. We qualitatively explain our observation based on internal mode excitations in combination with a field-like spin–orbit torque, showing that one must go beyond the usual rigid skyrmion description to understand the dynamics.

Published
2017
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34. Direct Observation of Zhang-Li Torque Expansion of Magnetic Droplet Solitons.

Author

Sunjae Chung, Le, Q. Tuan, Ahlberg, Martina, Awad, Ahmad A., Weigand, Markus, Bykova, Iuliia, Khymyn, Roman, Dvornik, Mykola, Mazraati, Hamid, Houshang, Afshin, Jiang, Sheng, Nguyen, T. N. Anh, Goering, Eberhard, Schütz, Gisela, Gräfe, Joachim, and Åkerman, Johan

Subjects
*DISCONTINUOUS precipitation, *ELECTRON-hole droplets, *HARMONIC oscillators
Abstract

Magnetic droplets are nontopological dynamical solitons that can be nucleated in nanocontact based spin torque nano-oscillators (STNOs) with perpendicular magnetic anisotropy free layers. While theory predicts that the droplet should be of the same size as the nanocontact, its inherent drift instability has thwarted attempts at observing it directly using microscopy techniques. Here, we demonstrate highly stable magnetic droplets in all-perpendicular STNOs and present the first detailed droplet images using scanning transmission X-ray microscopy. In contrast to theoretical predictions, we find that the droplet diameter is about twice as large as the nanocontact. By extending the original droplet theory to properly account for the lateral current spread underneath the nanocontact, we show that the large discrepancy primarily arises from current-in-plane Zhang-Li torque adding an outward pressure on the droplet perimeter. Electrical measurements on droplets nucleated using a reversed current in the antiparallel state corroborate this picture. [ABSTRACT FROM AUTHOR]

Published
2018
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