Publications (45)
Spin-orbit torque-driven skyrmion dynamics revealed by time-resolved X-ray microscopy
Seonghoon Woo, Kyung Mee Song, Hee-Sung Han +10
Magnetic skyrmions are topologically-protected spin textures with attractive properties suitable for high-density and low-power spintronic device applications. Much effort has been…
Universal criterion and phase diagram for switching a magnetic vortex core in soft magnetic nanodots
Ki-Suk Lee, Sang-Koog Kim, Young-Sang Yu +4
The universal criterion for ultrafast vortex-core switching between the up- and down-core bistates in soft magnetic nanodots was investigated by micromagnetic simulations along wit…
Curvature induced modifications of chirality and magnetic configuration in perpendicular magnetized films
David Raftrey, Dhritiman Bhattacharya, Colin Langton +8
Designing curvature in three-dimensional (3D) magnetic nanostructures enables controlled manipulation of local energy landscapes, allowing for the modification of noncollinear spin…
Fabrication and optical characterization of long-range surface-plasmon-polariton waveguides in the NIR
Markus Weber, Johannes Trapp, Florian Boehm +6
We experimentally demonstrate the propagation of long-range surface plasmon-polaritons in a nobel metal stripe waveguide at an optical wavelength of 780 nm. To minimize propagation…
Quantifying the Topology of Magnetic Skyrmions in three Dimensions
David Raftrey, Simone Finizio, Rajesh V. Chopdekar +7
Magnetic skyrmions have so far been treated as two-dimensional spin structures characterized by a topological winding number describing the rotation of spins across the skyrmion. H…
Tunable energy transfer between dipolar-coupled magnetic disks by stimulated vortex gyration
Hyunsung Jung, Ki-Suk Lee, Dae-Eun Jeong +9
A wide variety of coupled harmonic oscillators exist in nature1. Coupling between different oscillators allows for the possibility of mutual energy transfer between them2-4 and the…
Megahertz-rate Ultrafast X-ray Scattering and Holographic Imaging at the European XFEL
Nanna Zhou Hagström, Michael Schneider, Nico Kerber +97
The advent of X-ray free-electron lasers (XFELs) has revolutionized fundamental science, from atomic to condensed matter physics, from chemistry to biology, giving researchers acce…
Curvature-mediated spin textures in magnetic multi-layered nanotubes
Elisabeth Josten, David Raftrey, Aurelio Hierro-Rodriguez +10
The scientific and technological exploration of artificially designed three-dimensional magnetic nanostructures opens the path to exciting novel physical phenomena, originating fro…
Revealing the Microscopic Mechanism of Displacive Excitation of Coherent Phonons in a Bulk Rashba Semiconductor
Peter Fischer, Julian Baer, Moritz Cimander +3
Changing the macroscopic properties of quantum materials by optically activating collective lattice excitations has recently become a major trend in solid state physics. One of the…
Photon shot-noise limited transient absorption soft X-ray spectroscopy at the European XFEL
Loïc Le Guyader, Andrea Eschenlohr, Martin Beye +61
Femtosecond transient soft X-ray Absorption Spectroscopy (XAS) is a very promising technique that can be employed at X-ray Free Electron Lasers (FELs) to investigate out-of-equilib…
Polarization-selective vortex-core switching by orthogonal Gaussian-pulse currents
Young-Sang Yu, Ki-Suk Lee, Hyunsung Jung +6
We experimentally demonstrate low-power-consumption vortex-core switching in magnetic nanodisks using tailored rotating magnetic fields that are produced with orthogonal and unipol…
Wave modes of collective vortex gyration in dipolar-coupled-dot-array magnonic crystals
Dong-Soo Han, Andreas Vogel, Hyunsung Jung +7
Lattice vibration modes are collective excitations in periodic arrays of atoms or molecules. These modes determine novel transport properties in solid crystals. Analogously, in per…
Unforeseen advantage of looser focusing in vacuum laser acceleration
Aitor De Andres, Shikha Bhadoria, Javier Tello Marmolejo +8
Acceleration of electrons in vacuum directly by intense laser fields, often termed vacuum laser acceleration (VLA), holds great promise for the creation of compact sources of high-…
Interface-Induced Phenomena in Magnetism
Frances Hellman, Axel Hoffmann, Yaroslav Tserkovnyak +24
This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially-driven magnetic effects and phenomena associated with spin-orbit coupling and in…
Artificial double-helix for geometrical control of magnetic chirality
Dédalo Sanz-Hernández, Aurelio Hierro-Rodriguez, Claire Donnelly +9
Chirality plays a major role in nature, from particle physics to DNA, and its control is much sought-after due to the scientific and technological opportunities it unlocks. For mag…
Spectacular - A Modular DAQ System for Microdosimetry
Matthias Knopf, Simon Waid, Daniel Radmanovac +8
Particle therapy using light ions like protons, helium ions or carbon ions enables precise tumor targeting with enhanced biological effectiveness while minimizing damage to healthy…
PETAT -- An ASIC for Simple and Efficient Readout of Large PET Scanners
Peter Fischer, Michael Ritzert, Thomas Kerschenbauer
Modern PET scanners based on scintillating crystals use solid state photo detectors for light readout. The small area of these devices is beneficial for spatial resolution, but als…
Design, Fabrication, and Characterization of Ta2O5 Photonic Strip Waveguides
Lars Liebermeister, Niko Heinrichs, Florian Böhm +6
Efficient coupling of single quantum emitters to guided optical modes of integrated optical devices is of high importance for applications in quantum information science as well as…
Colloquium: Quantum Properties and Functionalities of Magnetic Skyrmions
Alexander P. PetroviÄ, Christina Psaroudaki, Peter Fischer +2
Competing magnetic interactions may stabilize smooth magnetization textures that can be characterized by a topological winding number. Such textures, which are spatially localized…
Fact Finder -- Enhancing Domain Expertise of Large Language Models by Incorporating Knowledge Graphs
Daniel Steinigen, Roman Teucher, Timm Heine Ruland +6
Recent advancements in Large Language Models (LLMs) have showcased their proficiency in answering natural language queries. However, their effectiveness is hindered by limited doma…
Disentangling kinetics from thermodynamics in heterogeneous colloidal systems
Hamed Almohammadi, Sandra Martinek, Ye Yuan +2
Nucleation and growth (N&G) - the emergence of a new phase within an initially homogeneous one - is one of the most important physical phenomena by which gas-liquid, liquid-liquid…
Separating terahertz spin and charge contributions from ultrathin antiferromagnetic heterostructures
Thomas W. J. Metzger, Peter Fischer, Takashi Kikkawa +3
Femtosecond laser excitation of nanometer thin heterostructures comprising a heavy metal and a magnetically ordered material is known to result in the emission of terahertz radiati…
Influence of the interfacial tension on the microstructural and mechanical properties of microgels at fluid interfaces
Jacopo Vialetto, Natalie Nussbaum, Jotam Bergfreund +2
Microgels are soft colloidal particles constituted by cross-linked polymer networks with a high potential for applications. In particular, after adsorption at a fluid interface, in…
Observation of room temperature magnetic skyrmions and their current-driven dynamics in ultrathin Co films
Seonghoon Woo, Kai Litzius, Benjamin Krüger +11
Magnetic skyrmions are topologically-protected spin textures that exhibit fascinating physical behaviors and large potential in highly energy efficient spintronic device applicatio…
Controlled Ordering of Room-Temperature Magnetic Skyrmions in a Polar Van der Waals Magnet
Peter Meisenheimer, Hongrui Zhang, David Raftrey +10
Control and understanding of ensembles of skyrmions is important for realization of future technologies. In particular, the order-disorder transition associated with the 2D lattice…
Complex fluids in the animal kingdom
Patrick A. Rühs, Jotam Bergfreund, Pascal Bertsch +2
Animals have evolved distinctive survival strategies in response to constant selective pressure. In this review, we highlight how animals exploit complex flow phenomena by manipula…
Single Photon Counting X-ray Imaging with Si and CdTe Single Chip Pixel Detectors and Multichip Pixel Modules
Peter Fischer, Sven Krimmel, Hans Krueger +5
Multichip modules (MCM) with 4 single photon counting MPEC 2.3 chips bump bonded to 1.3 cm x 1.3 cm large CdTe and Si semiconductor sensors as well as to single chip pixel detector…
Optimized computation of tight focusing of short pulses using mapping to periodic space
Elena Panova, Valentin Volokitin, Evgeny Efimenko +9
When a pulsed, few-cycle electromagnetic wave is focused by optics with f-number smaller than two, the frequency components it contains are focused to different regions of space, b…
Fixed points of quantum gravity in higher dimensions
Peter Fischer, Daniel F. Litim
We study quantum gravity in more than four dimensions by means of an exact functional flow. A non-trivial ultraviolet fixed point is found in the Einstein-Hilbert theory. It is sho…
Periodicity staircase in a Fe/Gd magnetic thin film
Arnab Singh, Junli Li, Sergio A. Montoya +7
Presence of multiple competing periodicities may result in a system to go through states with modulated periodicities, an example of which is the self-similar staircase-like struct…
Multi-task Localization and Segmentation for X-ray Guided Planning in Knee Surgery
Florian Kordon, Peter Fischer, Maxim Privalov +6
X-ray based measurement and guidance are commonly used tools in orthopaedic surgery to facilitate a minimally invasive workflow. Typically, a surgical planning is first performed u…
Fixed points of quantum gravity in extra dimensions
Peter Fischer, Daniel F. Litim
We study quantum gravity in more than four dimensions with renormalisation group methods. We find a non-trivial ultraviolet fixed point in the Einstein-Hilbert action. The fixed po…
Probing the spin polarization of current by soft X-ray imaging of current-induced magnetic vortex dynamics
Shinya Kasai, Peter Fischer, Mi-Young Im +5
Time-resolved soft X-ray transmission microscopy is applied to image the current-induced resonant dynamics of the magnetic vortex core realized in a micronsized Permalloy disk. The…
Sub-nanosecond signal propagation in anisotropy engineered nanomagnetic logic chains
Zheng Gu, Mark E. Nowakowski, David B. Carlton +13
Energy efficient nanomagnetic logic (NML) computing architectures propagate and process binary information by relying on dipolar field coupling to reorient closely-spaced nanoscale…
Element-Specific First Order Reversal Curves Measured by Magnetic Transmission X-ray Microscopy
Dustin A. Gilbert, Mi-Young Im, Kai Liu +1
The first order reversal curve (FORC) method is a macroscopic measurement technique which can be used to extract quantitative, microscopic properties of hysteretic systems. Using m…
Aerial LaneNet: Lane Marking Semantic Segmentation in Aerial Imagery using Wavelet-Enhanced Cost-sensitive Symmetric Fully Convolutional Neural Networks
Seyed Majid Azimi, Peter Fischer, Marco Körner +1
The knowledge about the placement and appearance of lane markings is a prerequisite for the creation of maps with high precision, necessary for autonomous driving, infrastructure m…
Design of a Large Area Digital SiPM with High Fill Factor and Fully Serial Digital Readout for Single Photon Detection in Liquid Noble Gas Detectors
Peter Fischer, Michael Keller, Michael Ritzert
We present a 'digital SiPM' photo-detection chip combining single photon sensitive avalanche photo diodes and CMOS readout electronics on a single die. The chip has a size of $8046…
Generation of Bloch Points with Controlled Spin Texture Using Geometrical Boundary Conditions
Naëmi Leo, Daniel Wolf, Alicia Estela Herguedas Alonso +16
Bloch points are three-dimensional topological singularities in magnetization that play a key role in topological transformations of spin textures, such as skyrmion creation or ann…
Thermo-Rheological Memory of -Carrageenan Fluid Gels Formed Under Flow
Julien Bauland, Tim J. Wooster, Peter Fischer +1
Fluid gels are soft materials formed by shearing biopolymer solutions during the sol-gel transition. Their ability to yield and flow beyond a critical stress makes them attractive…
On Ultrafast X-ray Methods for Magnetism
Rajan Plumley, Sathya Chitturi, Cheng Peng +36
With the introduction of x-ray free electron laser sources around the world, new scientific approaches for visualizing matter at fundamental length and time-scales have become poss…
Metric-Driven Learning of Correspondence Weighting for 2-D/3-D Image Registration
Roman Schaffert, Jian Wang, Peter Fischer +2
Registration of pre-operative 3-D volumes to intra-operative 2-D X-ray images is important in minimally invasive medical procedures. Rigid registration can be performed by estimati…
Dilated FCN for Multi-Agent 2D/3D Medical Image Registration
Shun Miao, Sebastien Piat, Peter Fischer +4
2D/3D image registration to align a 3D volume and 2D X-ray images is a challenging problem due to its ill-posed nature and various artifacts presented in 2D X-ray images. In this p…
Memory-bit selective recording in vortex-core cross-point architecture
Young-Sang Yu, Hyunsung Jung, Ki-Suk Lee +2
In our earlier work [Appl. Phys. Lett. 92, 022509 (2008)], we proposed nonvolatile vortex random access memory (VRAM) based on the energetically stable twofold ground state of vort…
Curvilinear magnonic crystal based on 3D hierarchical nanotemplates
Gianluca Gubbiotti, Olha Bezsmertna, Oleksandr V. Pylypovskyi +11
Curvilinear magnetic nanostructures enable control of magnetization dynamics through geometry-induced anisotropy and chiral interactions as well as magnetic field modulation. In th…
The interplay of local electron correlations and ultrafast spin dynamics in fcc Ni
Tobias Lojewski, Mohamed F. Elhanoty, Loïc Le Guyader +48
The complex electronic structure of metallic ferromagnets is determined by a balance between exchange interaction, electron hopping leading to band formation, and local Coulomb rep…