An interesting phenomenon occurs in submicron, magnetic vortex ground state particles as their thickness is increased, and the vortex becomes a fully-fledged three dimensional object. Although the ground state remains largely homogeneous through the thickness, one but needs to apply the smallest of excitation to see the emergent shearing of the magnetization texture and resonant modes associated with it [1,2]. Using the nanostencil fabrication technique[3] we obtained planar arrays of increasingly thick (up to 350 nm) magnetic particles, going beyond thicknesses studied previously. Not only do we observe the inversion of intensities of the modes, as high order modes become the most intense, we see also the complete disappearance of the homogeneous G0 mode, which marks a transition where the 2D dynamic solutions completely cease their existence, see the spectrum presented on Fig. 1. This new effect also goes toward a significant increase of the speed of dynamics in the system. In the course of study we place a special emphasis on taking the real, dome-like particle profiles into account, which, as we show, influence the spectra for thick particles significantly. The profiles used were attained with a help of atomic force microscopy. The realistic boundaries primarily tune the non-radiative standing spin wave modes[4] which in turn affect gyrational modes through hybridization. We observe this through the detailed, microscopic study of mode distributions such as the one on Fig. 2, by matching experimental spectra, and juxtaposing stationary trajectories (in the time domain).

![](https://assets.underline.io/uploads/markdown_image/1/image/8f782616bbfa5a82e7cffe9fbfba735f.jpg)

![](https://assets.underline.io/uploads/markdown_image/1/image/fc47f4d3547c1babcc525b8c1162cc50.jpg)

High Order Gyromode Observation in Dome-like Nanoparticles

High Order Gyromode Observation in Dome-like Nanoparticles

Extending nanostructures into the third dimension has become a major research avenue in modern magnetism and spintronics because of geometry-, curvature-, and topology-induced phenomena. Here, we introduce nanovolcanoes as on-demand engineered nano-architectures for 3D magnon spintronics. 40 nm-thick Co-Fe nanovolcanoes with diameters down to 300 nm were fabricated by the focused electron beam-induced deposition (FEBID) technique (Fig. 1) and studied by perpendicular spin-wave resonance (PSWR) spectroscopy. The spin-wave eigenfrequencies of the nanovolcanoes are notably different from the eigenfrequencies of the nanodisks and nanorings they are built from, because of the strongly non-uniform internal magnetic field. The experimental findings were elucidated with the aid of micromagnetic simulations, which indicate that the rings encircling the volcano craters lead to an effective confinement of the lower-frequency eigenmodes under the volcano crater, while the highest-frequency eigenmodes are confined in the ring area (Fig. 2). Accordingly, extension of 2D nanodisks into 3D nanovolcanoes allows to obtain same response in low frequency part of the spectrum in elements with 30% smaller footprints [1]. The nanovolcanoes can be viewed as multi-mode resonators with potential applications in telecom industry. Also, we demonstrated the engineering of the magnetic properties of CoFe-based nanodisks fabricated by FEBID. The material composition was tuned in situ via the e-beam waiting time in the deposition process and their post-growth irradiation with Ga ions. The saturation magnetization Ms of the nanodisks was deduced from PSWR measurements. The achieved variation of Ms in the broad range from 720 to 1430 emu/cm3 continuously bridges the gap between the Ms values of widely used magnonic materials such as Permalloy and CoFeB [2].

![](https://assets.underline.io/uploads/markdown_image/1/image/ca3695146d0c42bbf0d0b907eb2d1eb1.jpg)

Fig. 1. Atomic force microscopy image of the nanovolcano with the outer diameter of 300 nm and the crater diameter of 200 nm. Inset: cross-sectional line scan.

![](https://assets.underline.io/uploads/markdown_image/1/image/355d13301bed6b9caa1885c2c3af1f2e.jpg)

Fig. 2. Calculated spatial dependences of the spin-wave eigenfunctions for (a) 40 nm-thick nanovolcano NV300/200, (b) 20 nm-thick nanodisk ND300, and (c) 20 nm-thick nanoring NR300/200 at the out-of-plane bias magnetic field of 1.2 T.

Spin-wave spectra of 3D nanovolcanoes fabricated by focused electron beam-induced deposition

**Session chair:** Kyongmo An, Korea Research Institute of Standards and Science


HOA - Ferromagnetic Resonance

technical paper

The 15th Joint MMM-INTERMAG Conference (2022 Joint) is sponsored jointly by AIP Publishing and the IEEE Magnetics Society. Members of the international scientific and engineering communities interested in recent developments in fundamental and applied magnetism are invited to attend and contribute to the technical sessions. The technical program will include invited and contributed papers in oral and poster sessions, invited symposia, a plenary session, and an evening session, with about 1500 presentations overall. This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

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Please register for the Joint MMM-Intermag conference to join the event.

2022 Joint MMM-INTERMAG

This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

**Session chair:** Oleksii Volkov, Helmholtz-Zentrum Dresden-Rossendorf



Artem Bondarenko

2

2

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High Order Gyromode Observation in Dome-like Nanoparticles

Spin-wave spectra of 3D nanovolcanoes fabricated by focused electron beam-induced deposition

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