Publications | News about Team Members | News about Team Activities

Dr. Maria Azhar has been recognised as the "Physikerin der Woche" (Female physicist of the week) by the German Physical Society (DPG). The "Physikerin der Woche" initiative recognises female physicists based in Germany, as well as German women working internationally, for outstanding research. Among other research works, Dr. Azhar was recognised for her recent prediction of new topological defects known as screw dislocations. Congratulations to Dr. Maria Azhar on this achievement!

Ross Knapman of the TWIST Group successfully defended his doctoral thesis, titled "Creation and Manipulation of Topological Magnetic Textures in Chiral and Frustrated Magnets", on May 14, 2024, at the Johannes Gutenberg University Mainz.

In his thesis, Dr. Knapman focused on generating and controlling skyrmions and hopfions in chiral and frustrated magnets. Using computational and analytical methods, he investigated how these textures respond to external drives such as magnetic fields and currents.

Congratulations to Ross Knapman!

Link to his Thesis

A paper on "Manipulating vortices with domain walls in superconductor-ferromagnet heterostructures" has been published in Physical Review B. The authors delve into the interplay between vortices and domain walls in superconductor-ferromagnet heterostructures, underscoring the importance of exchange fields and spin-orbit coupling over conventional stray field models. Through simulations and theory, the paper elucidates how Rashba spin-orbit coupling influences magnetoelectric interactions, presenting opportunities for improved functionalities in heterostructure devices.

Detailed Information:
Manipulating vortices with domain walls in superconductor-ferromagnet heterostructures
S. A. Díaz, J. Nothhelfer, K. M. D. Hals, K. Everschor-Sitte
Physical Review B 109, L201110 (2024)

A paper on "Spacetime magnetic hopfions from internal excitations and braiding of skyrmions" has been published in Communications Physics. Here, the authors introduce spacetime magnetic hopfions, enhancing the dynamics of topological solitons. These magnetic textures develop spacetime topology when driven by a time-periodic force. The paper outlines construction methods and potential applications in nanopatterned grids and frustrated magnets, with adjustable topological properties offering new research directions.

Detailed Information:
Spacetime magnetic hopfions from internal excitations and braiding of skyrmions
R. Knapman, T. Tausendpfund, S. Díaz, K. Everschor-Sitte
Communications Physics 7, 151 (2024)

A paper on "Rechnen mit magnetischen Wirbeln" (Calculating with Magnetic Whirls) has been published in Physik in unserer Zeit. The authors delve into the utilization of material dynamics for physical reservoir computing. They highlight nanoscale magnetic patterns, such as skyrmions, which act as efficient and controllable reservoirs compatible with modern hardware. These systems demonstrate exceptional performance in tasks like spoken-digit recognition and benchmark problems.

Detailed Information:
Rechnen mit magnetischen Wirbeln
K. Everschor-Sitte, R. Msiska, A. Majumdar
Physik in unserer Zeit, 55: 183-189 (2024)

Kübra Kalkan joins the TWIST Group as a PhD Candidate. We are looking forward to a successful collaboration.

Contact information:
Kübra Kalkan
Office: MG 385
Email: kuebra.kalkan@uni-due.de

A roadmap for “unconventional computing with nanotechnology” has been published in Nano Futures. This collaboration between Giovanni Finocchio from the University of Messina, Karin Everschor-Sitte from the University of Duisburg-Essen, and others provides a comprehensive roadmap for neuromorphic computing using electron spins, memristive devices, two-dimensional nanomaterials, nanomagnets, and various dynamical systems. They also address computational paradigms such as Reservoir Computing, Ising machines, Bayesian inference engines, probabilistic computing with p-bits, processing in memory, etc.

Detailed Information:
Roadmap for unconventional computing with nanotechnology
G. Finocchio, ..., K. Everschor-Sitte, et al.
Nano Futures 8, 012001 (2024)

A focus issue on “Topological Solitons for Neuromorphic Systems” has been published in Neuromorphic Computing and Engineering. This collaboration between Prof. Dennis Meier from the Norwegian University of Science and Technology, Prof. Jorge Iñiguez from the Luxembourg Institute of Science and Technology & University of Luxembourg, Prof. Davi Rodrigues from Politecnico di Bari in Italy, and Prof. Karin Everschor-Sitte from the University of Duisburg-Essen covers the recent progress in the field of neuromorphic systems based on topological solitons.

Detailed Information:
Focus issue on Topological Solitons for Neuromorphic Systems
D. Meier, J. Iñiguez-Gonzalez, D. Rodrigues, and K. Everschor-Sitte
Neuromorphic Computing and Engineering 4, 010202 (2024)

Robin Msiska has won the Lightning Talks Session award at the MMM 2023 Conference in Dallas, TX. Sponsored by AIP Publishing and the IEEE Magnetics Society, the event required young professionals to present their research in a three-minute format. Congratulations to Robin Msiska!

A paper on “Spatial analysis of physical reservoir computers” has been published in Physical Review Applied. This paper introduces task-agnostic spatial measures for efficiently evaluating nonlinearity and memory in magnetic skyrmion-based reservoirs, enabling parallel parameter searches. The research unveils a natural trade-off between memory and nonlinearity, paving the way for enhanced performance in specific tasks. This advancement in spatial analysis offers valuable insights for designing energy-efficient and high-performance reservoirs.

Detailed Information:
Spatial analysis of physical reservoir computers
J. Love, R. Msiska, J. Mulkers, G. Bourianoff, J. Leliaert, and K. Everschor-Sitte
Physical Review Applied 20, 044057 (2023)

Prof. Karin Everschor-Sitte has been selected as the 2024 Wohlfarth Lecturer by the UK Institute of Physics magnetism group and the IEEE Magnetics Society UK & Ireland chapter. This honor recognizes her contributions to the fields of topologically protected magnetic structures and unconventional computing. She will present the Wohlfarth Memorial Lecture at the Magnetism 2024 conference in Loughborough, UK, on March 25th and 26th, 2024. Congratulations to Prof. Karin Everschor-Sitte on this well-deserved recognition.

More informations about Magnetism 2024

A paper on "Voltage-Controlled High-Bandwidth Terahertz Oscillators Based on Antiferromagnets" has been published in Physical Review Letters. This collaboration between Mike Lund and Prof. Kjetil Hals from the University of Agder in Norway, Prof. Davi Rodrigues from Politecnico di Bari in Italy, and Prof. Karin Everschor-Sitte from the University of Duisburg-Essen investigates theoretical self-oscillations in nonlinear antiferromagnets with a kagome lattice structure in the THz range, driven by spin-orbit torques.

Detailed Information:
Voltage-Controlled High-Bandwidth Terahertz Oscillators Based on Antiferromagnets
M. Lund, D. Rodrigues, K. Everschor-Sitte, and K. Hals
Physical Review Letters 131, 156704 (2023)

Dr. Maria Azhar joins the TWIST Group as a Postdoctoral Researcher. We are looking forward to a successful collaboration.

Contact information:
Dr. Maria Azhar
Office: MG 386
Email: maria.azhar@uni-due.de

Jonas Nothhelfer of the TWIST Group at the University of Duisburg-Essen successfully defended his doctoral thesis, titled "Topological excitations in magnets, superconductors, and magnet–superconductor heterostructures", on July 31, 2023, and has officially been awarded the title Dr. rer. nat. Nothhelfer.

In his thesis, Dr. Nothhelfer investigated topological excitations in magnetic and superconducting systems as well as in their hybrid structures.

Congratulations to Jonas Nothhelfer!

Link to Thesis 

Dr. Atreya Majumdar joins the TWIST Group as a Postdoctoral Researcher. We are looking forward to a successful collaboration.

Contact information:
Dr. Atreya Majumdar
Office: MG 384
Email: atreya.majumdar@uni-due.de

Dr. Amin Khavasi joins the TWIST Group as an Associate Professor. We are looking forward to a successful collaboration.

Contact information:
Dr. Amin Khavasi
Office: MG 389
Email: amin.khavasi@uni-due.de

Sandra Chulliparambil Shaju joins the TWIST Group as a PhD Candidate. We are looking forward to a successful collaboration.

Contact information:
Sandra Chulliparambil Shaju
Office: MG 389
Email: sandra.chulliparambil-shaju@uni-due.de

Dr. Nasim Bazazzadeh joins the TWIST Group as a Postdoctoral Researcher. We are looking forward to a successful collaboration.

Contact information:
Dr. Nasim Bazazzadeh
Office: MG 388
Email: n_bazazzadeh@sbu.ac.ir

A paper on “Steering Majorana braiding via skyrmion-vortex pairs: A scalable platform” from Jonas Nothhelfer et al. resulting from a collaboration between Johannes Gutenberg University of Mainz, Technical University of Dresden, Reserach Center in Jülich, University of Cologne, University of Agder and University of Duisburg-Essen has been published in Physical Review B.
In this paper, they exploit the fact that skyrmion-vortex pairs in superconductor-ferromagnet heterostructures hosting Majorana zero modes can be easily controlled in two spatial dimensions, thereby contributing to the path towards scalable topological quantum computing.

Detailed information:
Steering Majorana braiding via skyrmion-vortex pairs: A scalable platform
J. Nothhelfer, S. A. Díaz, S. Kessler, T. Meng, M. Rizzi, K. M. D. Hals, K. Everschor-Sitte
Phys. Rev. B 105, 224509 (2022)

A paper on “Nonzero Skyrmion Hall Effect in Topologically Trivial Structures” resulting from a collaboration between Robin Msiska and Twist Group Leader Prof. Dr. Karin Everschor-Sitte affiliated with the University of Duisburg-Essen, Prof. Dr. Davi Rodrigues from Politecnico di Bari in Italy and Prof. Dr. Jonathan Leliaert from Ghent University in Belgium has been published in Physical Review Applied.
In this paper, they disprove the widely held assumption that the skyrmion Hall effect vanishes for overall topologically neutral structures such as (synthetic) antiferromagnetic skyrmions and skyrmionium. They show that for spin-orbit torque-driven objects the net Magnus force does not necessarily vanish.

Detailed information:
Nonzero Skyrmion Hall Effect in Topologically Trivial Structures
R. Msiska, D. R. Rodrigues, J. Leliaert, K. Everschor-Sitte
Phys. Rev. Applied 17, 064015 (2022)

A paper on “Skyrmion pinning energetics in thin film systems” resulting from a collaboration between different teams from the Johannes Gutenberg-University Mainz, Charles University Prague, and Twist Group Leader Prof. Dr. Karin Everschor-Sitte affiliated with the University of Duisburg-Essen, has been published in Nature Communications.
In this paper they investigate experimentally and theoretically the pinning effects of skyrmions, which often pose a challenge for device applications.

Detailed information:
Skyrmion pinning energetics in thin film systems
R. Gruber, J. Zázvorka, M. A. Brems, D. R. Rodrigues, T. Dohi, N. Kerber, B. Seng, M. Vafaee, K. Everschor-Sitte, P. Virnau, M. Kläui
Nature Communications 13, 3144 (2022)

We congratulate Lucas Görzen for winning the award of the Gutenberg Lehrkolleg (GLK) for his bachelor thesis in the Department 08 Physics, Mathematics and Computer Science at the Johannes Gutenberg University in Mainz. The GLK issues prizes for outstanding theses in recognition of special student achievements through selection committees for studies and teaching (FASL) in the departments. The prizewinner Lucas Görzen wrote his award-winning bachelor thesis on "Composite Topological Structures in Superconductor-Ferromagnet Heterostructures" under the supervision of Prof. Dr. Karin Everschor-Sitte and co-supervision of Dr. Sebastián Díaz and Jonas Nothhelfer in March 2021. The Twist team would like to thank Lucas for his scientific contribution to research on topological structures. An overview of all award winners can be found here: https://www.glk.uni-mainz.de/praemierung-studentischer-arbeiten/

A paper on “Dzyaloshinskii-Moriya induced spin-transfer torques in kagome antiferromagnets” resulting from a collaboration between Davi R. Rodrigues from University of Bari, Akshaykumar Salimath and Kjetil M. D. Hals from University of Agder as well as Twist Group Leader Karin Everschor-Sitte affiliated with the University of Duisburg-Essen, has been published in Physical Review B.
In this paper, they predict a new coupling mechanism between antiferromagnetic domain walls (DWs) and spin currents, produced by the relativistic Dzyaloshinskii-Moriya interaction (DMI) for kagome AFMs with broken mirror symmetry. In addition, they show that the DMI induces a highly nontrivial, twisted DW profile that is controllable via two linearly independent components of the spin accumulation.

Detailed information:
Dzyaloshinskii-Moriya induced spin-transfer torques in kagome antiferromagnets
D. R. Rodrigues, A. Salimath, K. Everschor-Sitte, K. M. D. Hals
Phys. Rev. B 105, 174401 (2022)

TWIST group member Robin Msiska is featured in UDE magazine CAMPUS:REPORT, chronicling his globe spanning academic career as well as recent experiences in Germany. He comments on his move from Mainz to Duisburg, lessons learned while studying in Japan and his hobbies such as digital art.

Full article in CAMPUS:REPORT (2022, Volume 1).

Dr. Jonathan Atteia joins the TWIST Group as a Postdoctoral Researcher. We are looking forward to a successful collaboration.

Contact information:
Dr. Jonathan Atteia
Office: MG 389
Email: jonathan.atteia@uni-due.de

Alessandro Pignedoli joins the TWIST Group as a PhD Candidate. We are looking forward to a successful collaboration.

Contact information:
Alessandro Pignedoli
Office: MG 386
Email: alessandro.pignedoli@uni-due.de

A paper on “Readout of an antiferromagnetic spintronics system by strong exchange coupling of Mn₂Au and Permalloy” resulting from a collaboration between different teams from the Johannes Gutenberg-University Mainz and Twist Group Leader Karin Everschor-Sitte affiliated with the University of Duisburg-Essen, has been published in Nature Communications.

In this paper, they demonstrate strong exchange coupling of the metallic antiferromagnet Mn₂Au that exhibits Néel spin-orbit torques with thin ferromagnetic Permalloy layers and show one-to-one imprinting of the antiferromagnetic on the ferromagnetic domain pattern. This allows to benefit from the well-established read-out methods of ferromagnets, while the essential advantages of antiferromagnetic spintronics like ultra-fast dynamics and stability are only slightly diminished.

Detailed information:
Readout of an antiferromagnetic spintronics system by strong exchange coupling of Mn₂Au and Permalloy
S. P. Bommanaboyena, D. Backes, L. S. I. Veiga, S. S. Dhesi, Y. R. Niu, B. Sarpi, T. Denneulin, A. Kovács, T. Mashoff, O. Gomonay, J. Sinova, K. Everschor-Sitte, D. Schönke, R. M. Reeve, M. Kläui, H.-J. Elmers and M. Jourdan
Nature Communications 12, 6539 (2021)

A paper on “Scalable computational measures for entropic detection of latent relations and their applications to magnetic imaging” resulting from a collaboration between Illia Horenko from University of Lugano in Switzerland, Terence O’Kane from University of Tasmania, the postdoctoral researcher Davi Rodrigues and Twist Group Leader Karin Everschor-Sitte both affiliated with the University of Duisburg-Essen, has been published in Communications in Applied Mathematics and Computational Science.

In this paper, they introduce two novel computationally-scalable data relation measures the latent dimension and the latent entropy taking into account latent temporal relations between processes of interest and analyse their mathematical and computational properties. They have the potential to assist current efforts to enhance the resolution of experimental techniques by providing key insights into the noisy observed data when common data measures fail. These results are highly relevant to detect subtle material inhomogeneity patterns in magnetic imaging. For example these data-driven tools can be used to visualize inhomogeneities in magneto-optical Kerr effect measurements and help to explicitly resolve impurities and pinning centres.

Detailed information:
Scalable computational measures for entropic detection of latent relations and their applications to magnetic imaging
I. Horenko, D. Rodrigues, T. O'Kane and K. Everschor-Sitte
Communications in Applied Mathematics and Computational Science 16, 2 (2021)

Congratulations to Jake Love winning the Best Picture Award 2021 of the DFG Priority Program SPP2137! Besides Jonathan Leliaert, George Bourianoff and Karin Everschor-Sitte, Jake Love from the TWIST team, affiliated with the University of Duisburg-Essen won the Best Picture Award 2021 at the Skyrmionics Picture Competition of the DFG Priority Program SPP2137 Skyrmionics – Topological Spin Phenomena in Real-Space for Applications. The awarded figure depicts a gradual overlay of the non-linearity (red) and memory capacity (blue) of a magnetic skyrmion reservoir computer.

A paper on “Spin-Wave Driven Bidirectional Domain Wall Motion in Kagome Antiferromagnets” resulting from a collaboration between K. M. D. Hals, A. Salimath both from University of Agder in Norway and the postdoctoral researcher D. R. Rodrigues and Twist Group Leader Karin Everschor-Sitte affiliated with the Johannes Gutenberg-University Mainz and the University of Duisburg-Essen, has been published in Physical Review Letters 127, 157203 (2021).

In this paper, they predict a mechanism to controllably manipulate domain walls in kagome antiferromagnets via a single linearly polarized spin-wave source. They showed that the speed and direction of the domain wall motion can be regulated by tuning the frequency of the applied spin wave. These results are highly relevant for applications in the field of antiferromagnetic insulator devices. The article is featured on the front cover of the Physical Review Letters Journal (Volume 127, Issue 15, 08 October 2021).

Detailed information:
Spin-Wave Driven Bidirectional Domain Wall Motion in Kagome Antiferromagnets
D. R. Rodrigues, A. Salimath, K. Everschor-Sitte, K. M. D. Hals
Phys. Rev. Let. 127, 157203 (2021)

Congratulations to Ross Knapman winnning the 3rd poster prize at IOPmaterials! Besides the first prize to Marcos Guimaraes from the University of Groningen and the second prize to Yang Sun from Columbia University, Ross Knapman from the TWIST team, affiliated with the Johannes Gutenberg-University Mainz and the University of Duisburg-Essen won the third prize of the IOPmaterials poster competition EmergingLeaders.

For further information, visit https://twitter.com/IOPmaterials/status/1440994393327116288.

A book chapter on “Current-Induced Dynamics of Chiral Magnetic Structures: Creation, Motion, and Applications” resulting from a collaboration between Jan Masell from RIKEN Center for Emergent Matter Science in Japan and Twist Group Leader Karin Everschor-Sitte, has been published in a book about Chirality, Magnetism and Magnetoelectricity.

In this work, they review how spin-transfer and spin-orbit-torques can be exploited to create and move chiral magnetic textures in magnets with broken inversion symmetries, including domain walls and skyrmions using electric currents.

Detailed information:
Current-Induced Dynamics of Chiral Magnetic Structures: Creation, Motion, and Applications
J. Masell and K. Everschor-Sitte
Book Chapter in Chirality, Magnetism and Magnetoelectricity. Topics in Applied Physics, Vol. 138, Springer (2021)

A paper on “Current-induced H-shaped-skyrmion creation and their dynamics in the helical phase” resulting from a collaboration between Jan Masell from RIKEN Center for Emergent Matter Science in Japan, PhD Candidate Ross Knapman, postdoctoral researcher Davi Rodrigues and Twist Group Leader Karin Everschor-Sitte affiliated with the Johannes Gutenberg-University Mainz and the University of Duisburg-Essen, has been published in Journal of Physics D.

In this paper, they propose a protocol to create topological magnetic structures in helical magnets, which confine the motion of skyrmions along one-dimensional channels formed by helices to allow high-speed skyrmion motion. They furthermore analyse the stability and current-driven motion of the skyrmions in a helical background with in-plane uniaxial anisotropy fixing the orientation of the helices. These results are highly relevant for skyrmion racetrack-like applications.

Detailed information:
Current-induced H-shaped-skyrmion creation and their dynamics in the helical phase
R. Knapman, D. R. Rodrigues, J. Masell, K. Everschor-Sitte
Journal of Physics D: Applied Physics 54 404003 (2021)

A paper on “Nonlinear Dynamics of Topological Ferromagnetic Textures for Frequency Multiplication” resulting from a collaboration between Morteza Mohseni and Philipp Pirro both from TU Kaiserslautern and postdoctoral researcher Davi R. Rodrigues, PhD Candidate Jonas Nothhelfer, PhD Candidate Ross Knapman and Twist Group Leader Karin Everschor-Sitte affiliated with the Johannes Gutenberg-University Mainz and the University of Duisburg-Essen, has been published in Physical Review Applied.

In this paper, they propose that the nonlinear radio-frequency dynamics and nanoscale size of topological magnetic structures associated with their well-defined internal modes advocate their use as in materio scalable frequency multipliers for spintronic systems. They explore the excitation of eigenmodes of of isolated ferromagnetic skyrmions by fractions of the corresponding eigenfrequencies.

Detailed information:
Nonlinear Dynamics of Topological Ferromagnetic Textures for Frequency Multiplication
D. R. Rodrigues, J. Nothhelfer, M. Mohseni, R. Knapman, P. Pirro K. Everschor-Sitte
Physical Review Applied 16, 014020 (2021)

Karin Everschor-Sitte has accepted a call for a professorship in Theoretical Physics at the University of Duisburg-Essen.

The press release of April 2021 can be found here.

A paper on “A deeper look into natural sciences with physics-based and data-driven measures” resulting from a collaboration between Illia Horenko from University of Lugano in Switzerland, Susanne Gerber from Medical Center of the Johannes Gutenberg University Mainz, postdoctoral researcher Davi R. Rodrigues and Twist Group Leader Karin Everschor-Sitte both affiliated with the Johannes Gutenberg-University Mainz, has been published in iScience.

In this paper, they discuss two state-of-the-art machine learning data-driven tools latent entropy and latent dimension to analyse latent effects in data to glean much more information from an experimental data set to study matter. They explain the applicability of those techniques in natural science to reveal so far unobserved features on several examples like a gradient in a magnetic measurement or a latent network of glymphatic channels from the mouse brain microscopy data.

Detailed information:
A deeper look into natural sciences with physics-based and data-driven measures
D. R. Rodrigues, K. Everschor-Sitte, S. Gerber, I. Horenko
iScience 24, 3 (2021)

A paper on “The promise of spintronics for unconventional computing” by Giovanni Finocchio, Massimiliano Di Ventra, Kerem Y. Camsari, Karin Everschor-Sitte, Pedram Khalili Amiri and Zhongming Zeng, has been published in Journal of Magnetism and Magnetic Materials.

In this paper, they discuss how spintronics primarily focusing on magnetic tunnel junctions may aid in the realization of efficient devices which provide solutions to complex problems with reduced time, power consumption and/or less device footprint than is currently possible with standard approaches. They provide a perspective on how these devices can impact the development of three unconventional computing paradigms, namely, reservoir computing, probabilistic computing and memcomputing.

Detailed information:
The promise of spintronics for unconventional computing
G. Finocchio, M. Di Ventra, K. Y. Camsari, K. Everschor-Sitte, P. K. Amiri, Z. Zeng
Journal of Magnetism and Magnetic Materials 521, 167506 (2021)

A paper on “Reliability of genomic variants across different next-generation sequencing platforms and bioinformatic processing pipelines” has been published in BMC Genomics.

In this paper, they provide empirical evidence of systematic heterogeneity in single nucleotide variant calls between alternative experimental and data analysis setups based on Next Generation Sequencing.

Detailed information:
Reliability of genomic variants across different next-generation sequencing platforms and bioinformatic processing pipelines
S. Weißbach, S. Sys, C. Hewel, H. Todorov, S. Schweiger, J. Winter, M. Pfenninger, A. Torkamani, D. Evans, J. Burger, K. Everschor-Sitte, H. L.May-Simera, S. Gerber
BMC Genomics 22, 62 (2021)

Dr. Sarah Jenkins joins the TWIST Group as a Postdoctoral Researcher.

We are looking forward to a successful collaboration.

Kyra Klos joins the TWIST Group joint with the Group of Friederike Schmid as a PhD Candidate.

We are looking forward to a successful collaboration.