Microwave magnetoelectric effect via skyrmion resonance modes in a helimagnetic multiferroic

• Published in: Nature communications 2013-08, Vol.4 (1), p.2391-2391, Article 2391
• Main Authors: Okamura, Y., Kagawa, F., Mochizuki, M., Kubota, M., Seki, S., Ishiwata, S., Kawasaki, M., Onose, Y., Tokura, Y.
• Format: Article
• Language: English
• Subjects: 639/766/119/996; 639/766/119/997; 639/766/25; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms3391

Magnetic skyrmion, a topologically stable spin-swirling object, can host emergent electromagnetism, as exemplified by the topological Hall effect and electric-current-driven skyrmion motion. To achieve efficient manipulation of nano-sized functional spin textures, it is imperative to exploit the resonant motion of skyrmions, analogously to the role of the ferromagnetic resonance in spintronics. The magnetic resonance of skyrmions has recently been detected with oscillating magnetic fields at 1–2 GHz, launching a search for new skyrmion functionality operating at microwave frequencies. Here we show a microwave magnetoelectric effect in resonant skyrmion dynamics. Through microwave transmittance spectroscopy on the skyrmion-hosting multiferroic crystal Cu 2 OSeO 3 combined with theoretical simulations, we reveal nonreciprocal directional dichroism (NDD) at the resonant mode, that is, oppositely propagating microwaves exhibit different absorption. The microscopic mechanism of the present NDD is not associated with the conventional Faraday effect but with the skyrmion magnetoelectric resonance instead, suggesting a conceptually new microwave functionality. Magnetic skyrmions are topologically stable swirls in a spin structure. Here, the authors demonstrate new ways of controlling them by showing that the absorption of an electromagnetic wave by a skyrmion depends on the direction of incidence and that the resonance modes respond to a magnetic field.