What is it about?

Hopfions are three-dimensional nanoscale magnetization states that can occur in a ferromagnetic material. Although predicted theoretically, they remain hidden from experimental detection. This is mainly due to their small size and difficulties in visualizing the magnetization state inside the material. By calculating the full spin-wave spectra of hopfion in the microwave range we propose a new method for their spectral identification.

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Why is it important?

We show that the spin-wave spectra of hopfions in the microwave frequency range are very rich and consist of four main groups of spin-wave modes. We identified and visualized all the mode groups and calculated the resonance spectra expected from the ferromagnetic resonance measurements in the two main magnetic field configurations. The obtained results indicate that spin-wave resonance may be useful in the identification of hopfions using standard measurement techniques.


I believe, very interesting physics will be soon discovered with hopfions, and some of their properties may be interesting for applications in sensing or information processing and storage. In this paper, we show full spin-wave spectra of 3D magnetic hopfion, which is very rich and thus offers plenty of options for interaction with magnetization dynamics, thus could be useful for application in magnonics.

Maciej Krawczyk
Uniwersytet im Adama Mickiewicza w Poznaniu

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This page is a summary of: Magnon spectrum of Bloch hopfion beyond ferromagnetic resonance, APL Materials, September 2022, American Institute of Physics,
DOI: 10.1063/5.0100484.
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