Pattern recognition with a magnon-scattering reservoir

Magnons are elementary excitations in magnetic materials and undergo nonlinear multimode scattering processes at large input powers. In experiments and simulations, we show that the interaction between magnon modes of a confined magnetic vortex can be harnessed for pattern recognition. We study the magnetic response to signals comprising sine wave pulses with frequencies corresponding to radial mode excitations. Three-magnon scattering results in the excitation of different azimuthal modes, whose amplitudes depend strongly on the input sequences. We show that recognition rates above 95\% can be attained for four-symbol sequences using the scattered modes, with strong performance maintained with the presence of amplitude noise in the inputs

Tailoring crosstalk between localized 1D spin-wave nanochannels using focused ion beams

1D spin-wave conduits are envisioned as nanoscale components of magnonics-based logic and computing schemes for future generation electronics. `A-la-carte methods of versatile control of the local magnetization dynamics in such nanochannels are highly desired for efficient steering of the spin waves in magnonic devices. Here, we present a study of localized dynamical modes in 1-$\mu$m-wide Permalloy conduits probed by microresonator ferromagnetic resonance technique. We clearly observe the lowest-energy edge mode in the microstrip after its edges were finely trimmed by means of focused Ne$^+$ ion irradiation. Furthermore, after milling the microstrip along its long axis by focused ion beams, creating consecutively $\sim$50 and $\sim$100 nm gaps, additional resonances emerge and are attributed to modes localized at the inner edges of the separated strips. To visualize the mode distribution, spatially resolved Brillouin light scattering microscopy was used showing an excellent agreement with the ferromagnetic resonance data and confirming the mode localization at the outer/inner edges of the strips depending on the magnitude of the applied magnetic field. Micromagnetic simulations confirm that the lowest-energy modes are localized within $\sim$15-nm-wide regions at the edges of the strips and their frequencies can be tuned in a wide range (up to 5 GHz) by changing the magnetostatic coupling (i.e. spatial separation) between the microstrips.Comment: 10 pages, 4 figure

Data publication: Experimental characterization of four-magnon scattering processes in ferromagnetic conduits

All Raw and Processed Data + written Thesis. Data and Figures are stored in the 'Figures_and_Data' Directory. Experimental Measurements were done by means of BLS Microscopy (group of H. Schultheiß at HZDR). Micromagnetic Simulations were done at the Hemera Cluster (Dr. A. Kakay at HZDR). Data Analysis was done in Python or Jupyter Notebooks (Open Source). All scripts are included. Graphics were done using OmniGraffle and Blender. Plotting was done using Python and 'Plot2' (Mac Only!). All Files/Data/Skripts are sorted by Figure! The entire Latex Package is stored under 'Thesis_Hula' - Dissertation.tex is the main file and shows all required dependencies

Nonlocal stimulation of three-magnon splitting in a magnetic vortex

We present a combined numerical, theoretical and experimental study on stimulated three-magnon splitting in a magnetic disk in the vortex equilibrium state. Our micromagnetic simulations and Brillouin-light-scattering results confirm that three-magnon splitting can be triggered even below threshold by exciting one of the secondary modes by magnons propagating in a waveguide next to the disk. The experiments show that stimulation is possible over an extended range of excitation powers and a wide range of frequencies around the eigenfrequencies of the secondary modes. Rate-equation calculations predict an instantaneous response to stimulation and the possibility to prematurely trigger three-magnon splitting even above threshold in a sustainable manner. These predictions are confirmed experimentally using time-resolved Brillouin-light-scattering measurements and are in a good qualitative agreement with the theoretical results. We believe that the controllable mechanism of stimulated three-magnon splitting could provide a possibility to utilize magnon-based nonlinear networks as hardware for reservoir or neuromorphic computing. Here, we briefly describe how the archived data for the publication "Nonlocal stimulation of three-magnon splitting in a magnetic vortex", submitted to PRL, is structured. "rate-equations" - theoretical data of the temporal evolution of the spin wave modes in Fig. 4 "micromagnetic-simulation" - MuMax3 simulation recipes (.go files) and sample-layout masks for the simulations performed for Fig. 2(a,b,c). - corresponding power spectra obtained with our "mumax3-pwsp" program - mode profiles for stimulated and spontaneous splitting (Fig. 1(c) and Fig. 2(d)) - dispersion of the spin waves, calculated by micromagetnic simulation, shown in Fig. 1(b) "experiments" - electron beam microscopy image of the sample - intensity spectrum of the waveguide, used to calculate the approximate frequency/wave-vector region where the waveguide is effective (inset in Fig. 1(c)) - non-time-resolved BLS measurements, including spectra, power sweeps, etc. for Figs 2,3 in "i3MS" folders, in more detail described by "i3MS_V1_KS_logbook.pdf" - time-resolved BLS measurements, further explained in the corresponding subfolder

Data publication: Pattern recognition in reciprocal space with a magnon-scattering reservoir

This data publication contains the data for our publication "Pattern recognition in reciprocal space with a magnon-scattering reservoir" published in Nature Communications. The dataset is structured in folders corresponding to the different figures in the paper. Folder Fig2 and Fig2 contain the experimental data measured with Brillouin-light-scattering microscopy. The files contain the data integrated for the measurement positions described in the methods section in a csv format. Forlder Fig4 contains the evaluated numerical data presented in the corresponding figure. The raw data generated with micromagnetic simulations is too large for this dataset and is available upon request by the authors

Agility of spin Hall nano-oscillators

Data repository for manuscript submitted to Physical Review Applied: Agility of spin Hall nano-oscillators. DATA fingerprint for resubmitted: md5:a9bbd503a5370963b835d3c40cdf8ba8 Ignore the older onesmd5:36e53eb278f8c3073a51de6c709f72c8 (Ignore md5:3e2ddf76473149ad1d58cf100f90321f , I am unable to remove it, it is just an incomplete submission) Data organised on a figure by figure basis. The provided file- How to navigate the data- links all the data sets and data handling scripts utilised on each figure. Ipython notebook was used in the data handling and Omnigraffle was used to assemble the sub-figures and label the plots produced in via the Ipython notebooks. Data shown in the corresponding plots can be found in the .txt files with same labelling as figures. Abstract. We investigate the temporal response of constriction-based spin Hall nano-oscillators driven by pulsed stimuli using time-resolved Brillouin light scattering microscopy. The growth rate of the magnetization auto-oscillations, enabled by spin Hall effect and spin orbit torque, is found to vary with the amplitude of the input voltage pulses, as well as the synchronization frequency set by an external microwave input. The combination of voltage and microwave pulses allows to generate auto-oscillation signals with multi-level amplitude and frequency in the time-domain. Our findings suggest that the lead time of processes such as synchronization and logic using spin Hall nano-oscillators can be reduced to the nanosecond time-scale

Data publication: Control of Four-Magnon Scattering by Pure Spin Current in a Magnonic Waveguide

This dataset contains the numerical and experimental data (both raw and evaluated), labbooks associated with the measurements for our paper published in Physical Review Applied

Data for: Mapping the stray fields of a micromagnet using spin centers in SiC

We utilized the following methods to obtain the presented data: optically detected magnetic resonance (ODMR), photoluminescence spectroscopy, and micromagnetic simulations in Mumax3. The experimental data were obtained on the sample which is labeled as: "HPSI 4H-SiC 30 Magnon Q #2". On that sample we investigated magnetic ellipses, sized 8 micrometer x 2 micrometer, made of Permalloy, that lie on top of a silicon carbide substrate. The measured data for all measurements (including ALL parameters) are included in the uploaded primary data subdirectories. The uploaded data is organized in folders according to the figures in the paper. Each folder contains the experimental data, together with the MuMax3 definition files, all the possible possible scripts used for evaluation and all figures included in the paper. This is the final version with the reviewers' corrections.This is the final version of the manuscript's files