Contact

Porträt Dr. Kakay, Attila; FWIN

Dr. Attila Kakay

a.kakayAthzdr.de
Phone: +49 351 260 2689

Curvilinear Micromagnetism

Recent progress in material science has enabled the first experimental studies concerning the static magnetization characterization of samples with tubular geometry, such as rolled-up structures, nanowires and nanotubes. The bending of a flat thin-film to a curved surface introduces a break of the local inversion symmetry and can lead to surprising phenomena which do not unfold in flat geometries. As an example, domain walls in nanotubes  show a chiral symmetry breaking regarding their propagation and moreover can propagate so fast that can trigger a  Cherenkov-type spin-wave radiation. A further example is that this lack of inversion symmetry leads to an asymmetric dispersion relation for the spin waves regarding the sign of the propagation vector. This is a purely curvature induced effect with its origin in the classical dipole-dipole interaction. 

Using finite element micromagnetic simulations with our in-house developed program TetraMag (originally developed by Dr. Riccardo Hertel), we study the effect of the surface curvature on the statics and dynamics of typical spin textures as well as on the spin-wave propagation. The usual spin textures are domain walls, vorticies, Bloch points and Skyrmions formed in ferromagnetic nanowires and nanotubes. Although investigating spin-wave and domain-wall dynamics is still a challenge from experimental point of view, a combined effort of the experimental groups in our devision helps to confirm the results predicted by simulations.

Besides the basic research we develop the GPU accelerated micromagnetic codes used in our studies for the finite discretisation as well as for the finite element methods and all related programs required for the analysis of the simulations. 

 

Research Topics

  • Spin textures in curved geometries
  • Spin-wave propagation in curved nano-membranes
  • GPU accelerated micromagnetic code development

Group members

  • Lukas Körber - PhD student
  • Friedrich Zahn - Bachelor student
  • Gwendolyn Quasebarth - Bachelor student
  • Mirja Granfors - SHK student

Recent publications

Full list availabe here.

2020

Visualizing Magnetic Structure in 3D Nanoscale Ni–Fe Gyroid Networks

Llandro, J.; Love, D. M.; Kovács, A.; Caron, J.; Vyas, K. N.; Kakay, A.; Salikhov, R.; Lenz, K.; Faßbender, J.; Scherer, M. R. J.; Cimorra, C.; Steiner, U.; Barnes, C. H. W.; Dunin-Borkowski, R. E.; Fukami, S.; Ohno, H.

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Tunable magnetic vortex dynamics in ion-implanted permalloy disks

Ramasubramanian, L.; Kákay, A.; Fowley, C.; Yildirim, O.; Matthes, P.; Sorokin, S.; Titova, A.; Hilliard, D.; Böttger, R.; Hübner, R.; Gemming, S.; Schulz, S. E.; Kronast, F.; Makarov, D.; Faßbender, J.; Deac, A. M.

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2019

Experimental Observation of Exchange-Driven Chiral Effects in Curvilinear Magnetism

Volkov, O.; Kakay, A.; Florian, K.; Mönch, J. I.; Mohamad-Assaad, M.; Faßbender, J.; Makarov, D.

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Strain Anisotropy and Magnetic Domains in Embedded Nanomagnets

Nord, M.; Semisalova, A.; Kákay, A.; Hlawacek, G.; Maclaren, I.; Liersch, V.; Volkov, O.; Makarov, D.; Paterson, G. W.; Potzger, K.; Lindner, J.; Faßbender, J.; Mcgrouther, D.; Bali, R.

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Defect-Driven Magnetization Configuration of Isolated Linear Assemblies of Iron Oxide Nanoparticles

Rastei, M. V.; Pierron-Bohnes, V.; Toulemon, D.; Bouillet, C.; Kákay, A.; Hertel, R.; Tetsi, E.; Begin-Colin, S.; Pichon, B. P.

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  • Secondary publication expected from 09.09.2020

Magnetization Dynamics of an Individual Single-Crystalline Fe-Filled Carbon Nanotube

Lenz, K.; Narkowicz, R.; Wagner, K.; Reiche, C. F.; Körner, J.; Schneider, T.; Kákay, A.; Schultheiss, H.; Suter, D.; Büchner, B.; Fassbender, J.; Mühl, T.; Lindner, J.

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Zero-field dynamics stabilized by in-plane shape anisotropy in MgO-based spin-torque oscillators

Kowalska, E.; Kákay, A.; Fowley, C.; Sluka, V.; Lindner, J.; Fassbender, J.; Deac, A. M.
Related publications
Tunnel magnetoresistance angular and bias dependence … (Id 27885) is supplemented by this publication

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Excitation of whispering gallery magnons in a magnetic vortex

Schultheiss, K.; Verba, R.; Wehrmann, F.; Wagner, K.; Körber, L.; Hula, T.; Hache, T.; Kákay, A.; Awad, A. A.; Tiberkevich, V.; Slavin, A. N.; Fassbender, J.; Schultheiss, H.
  • Open Access Logo Physical Review Letters 122(2019), 097202
  • Invited lecture (Conferences)
    International Conference on Magnetism, 19.07.2018, San Francisco, USA
  • Invited lecture (Conferences)
    APS March Meeting, 04.03.2019, Boston, USA
  • Poster
    Wilhelm und Else Heraeus-Seminar “Spin Based Information Processing”, 08.01.2019, Bad Honnef, Deutschland
  • Lecture (Conference)
    Joint European Magnetic Symposia (JEMS), 04.09.2018, Mainz, Deutschland
  • Poster
    Magnonics 2019, 28.07.2019, Carovigno, Italien
  • Invited lecture (Conferences)
    Magnetics and Optics Research International Symposium, 24.06.2019, Prague, Czech Republic
  • Invited lecture (Conferences)
    Conference on Magnetism and Magnetic Materials (MMM), 06.11.2019, Las Vegas, USA

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Experimental and Theoretical Study of Curvature Effects in Parabolic Nanostripes

Volkov, O. M.; Kronast, F.; Mönch, I.; Mawass, M.-A.; Kákay, A.; Fassbender, J.; Makarov, D.

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Tunnel magnetoresistance angular and bias dependence enabling tuneable wireless communication

Kowalska, E.; Fukushima, A.; Sluka, V.; Fowley, C.; Kákay, A.; Aleksandrov, Y.; Lindner, J.; Fassbender, J.; Yuasa, S.; Deac, A. M.
Related publications
Zero-field dynamics stabilized by in-plane shape … (Id 28927) is a supplement to this publication

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Emission and Propagation of Multi-Dimensional Spin Waves in Anisotropic Spin Textures

Sluka, V.; Schneider, T.; Gallardo, R. A.; Kakay, A.; Weigand, M.; Warnatz, T.; Mattheis, R.; Roldan-Molina, A.; Landeros, P.; Tiberkevich, V.; Slavin, A.; Schütz, G.; Erbe, A.; Deac, A.; Lindner, J.; Fassbender, J.; Raabe, J.; Wintz, S.

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2018

Frequency linewidth and decay length of spin waves in curved magnetic membranes

Otalora, J. A.; Kákay, A.; Lindner, J.; Schultheiss, H.; Thomas, A.; Fassbender, J.; Nielsch, K.

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Origin and Manipulation of Stable Vortex Ground States in Permalloy Nanotubes

Zimmermann, M.; Gerhard-Meier, T. N.; Dirnberger, F.; Kákay, A.; Decker, M.; Wintz, S.; Finizio, S.; Josten, E.; Raabe, J.; Kronseder, M.; Bougeard, D.; Lindner, J.; Back, C. H.

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Multiplet of skyrmion states on a curvilinear defect: Reconfigurable skyrmion lattices

Kravchuk, V. P.; Sheka, D. D.; Kákay, A.; Volkov, O. M.; Rößler, U. K.; van den Brink, J.; Makarov, D.; Gaididei, Y.

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Contact

Dr. Attila Kakay

a.kakayAthzdr.de
Phone: +49 351 260 2689