Category: Papers
Pseudospectral method resolves atomic scale dynamics
We have published a new continuum method that resolves atomic-scale magnetization dynamics with good accuracy. The method is pseudospectral and so is amenable to analytical calculation. Limiting cases of modulational instability (a long-wave phenomenon) and transient grating (a regime where long and short waves co-exist) were resolved in excellent agreement with atomistic spin dynamics. We expect this model to be the foundational stone for a better modeling of topological textures.
Fantastic work by Kyle Rockwell on this research and special thanks to our international collaborators Joel Hirst and Thomas Ostler.
This research was supported by the U.S. Department of Energy, Office of Science.
Nano-magnonic crystals
Ally published her first-author investigation of magnonic band structure in nano-magnonic crystals. These are magnonic crystals with parameters modulated at the nanoscale which could leverage new techniques in material science with tens of nanometer resolution. Congratulations Ally!
The paper can be found at Magnetochemistry 10, 14 (2024)
Ultrafast domain-wall motion
We are very happy that our work on ultrafast magnetization dynamics has been published in Physical Review Letter as editors’ suggestion and featured in the Physics magazine. This collaborative work features experiments performed at FERMI free-electron laser in Italy. Based on the data, we were able to discern changes in the scattering and link them to curvature-dependent distortions in the domain pattern. Congratulations to all authors and special mention to Kyle’s work and contribution to this research!
The paper can be found in Phys. Rev. Lett. 131, 256702 (2023)
Published method for general ASI magnon band structure
Our work on Gænice has been published in J. Magn. Magn. Mater. 589, 171603 (2023). Very nice piece of work that will allow us to explore new artificial spin ice geometries with exciting magnonic functionalities.
The code is free to use and can be downloaded from our repository.
Numerical approach to approximate demag factors
Our method to determine demag factors for stadium-shaped nanoislands has been published in IEEE Magnetic Letters. This approach goes in tandem with Gænice to obtain a quantitative agreement with Kittel’s equation using the approximation of a diagonal demag tensor. The level of accuracy obtained allows us to resolve the resonant frequencies at low bias fields, as it is often the case in artificial spin ices.
Nonlinear magnon scattering in ASI
Experiments and simulations unveiled magnon scattering in ASIs due to nonlinear processes. These were only observed in continuous magnetic films but in our recent Nature Communications, we demonstrate that similar processes are allowed by the coupling between adjacent nanoislands in ASIs. Beautiful experiments done at M. B. Jungfliesch’s group!
Topological magnetic monopoles
The experimental identification of topological magnetic monopoles, or hedgehogs, was published in Nature Nanotechnology. Outstanding experiments performed at COSMIC allowing for an unprecedented 10 nm resolution in the 3D-reconstructed magnetization vector of a frustrated metalattice. We were able to determine the textures’ topology directly from experimental results, identifying both hedgehogs in the bulk of the materials and “virtual” hedgehogs whose topology is bound to the material’s surfaces. For more information, see the research highlight in the STROBE website.
Ultrafast domain-wall motion depends on symmetry
Measurements done at European XFEL showed that femtosecond optical pulses affect magnetic domains depending on their symmetry: labyrinth domains are mobile while stripe domains are virtually fixed. This observation was achieved by measuring samples with mixed states and developing a new analysis technique for 2D scattering data. This is our second editors’ suggestion on ultrafast magnetization dynamics published in Phys. Rev. B 106, 224424 (2022). Outstanding work from all the team and especially Nanna Zhou Hagström!
Domains move at picosecond timescales
Our investigation of ultrafast domain-wall dynamics has been published in Phys. Rev. B and selected as editor’s suggestion. By a thorough analysis of scattering data taken at LCLS, we were able to find both domain-wall broadening and a shift in the scattering peak position that is indicative that domains move upon optical perturbation at picosecond timescales. More details in our publication D. Zusin et al., Ultrafast domain dilation induced by optical pumping in ferromagnetic CoFe/Ni multilayers, Phys. Rev. B 106, 144422 (2022).
MHz-rate ultrafast dynamics at EU-XFEL
First results from the MHz-repetition-rate X-ray scattering experiments from the Spectroscopy and Coherent Scattering instrument were achieved by a team of international researchers. This technique will enable accurate analysis of collected X-ray ultrafast scattering data. More details at N. Zhou Hagström et al., MHz-rate ultrafast X-ray scattering and holographic imaging at the European XFEL, J. Synchrotron Rad. 29 (2022).