Yokouchi1,2, S. Sugimoto3, B. Rana1,4, S. Seki1,5,6,7, N. Ogawa1,5,6, Shiomi2, S. Kasai3,5, Y. Otani1,8,9
1RIKEN Center for Emergent Matter Science (CEMS), Japan
2Department of Basic Science, The University of Tokyo, Tokyo, Japan
3National Institute for Materials Science (NIMS), Tsukuba, Japan
4Institute of Spintronics and Quantum Information, Faculty of Physics, Adam Mickiewicz University, Poznań, Poland
5PRESTO, Japan Science and Technology Agency (JST), Tokyo, Japan
6Department of Applied Physics, The University of Tokyo, Tokyo, Japan
7Institute of Engineering Innovation, The University of Tokyo, Tokyo, Japan
8Institute for Solid State Physics (ISSP), The University of Tokyo, Japan
9Trans-scale Quantum Science Institute, University of Tokyo, Tokyo, Japan
Skyrmions offers great possibilities for applications. For example, because of ultralow current driven motion of skyrmion, skyrmion is considered as a promising candidate for an information bit in new magnetic storage devices [1]. In order to realize these devices, efficient ways to create skyrmions are highly demanded. So far, the creation of skyrmions has been demonstrated by employing local spin-orbit torque arising from an electric current flowing in multilayer films processed into special shapes with a notch or a constriction [2,3]. However, in these methods, the position where skyrmions are created is limited at a specific position of the multilayer films and relatively large current density is required
In this presentation, we demonstrate a novel approach for the creation of skyrmion, focusing on the interplay between the spins and strain resulting from surface acoustic waves (SAWs). A stack of Pt/Co/Ir was deposited on LiNbO3 substrate and surface acoustic waves were excited by using interdigital transducers (IDTs). When the surface acoustic wave is excited in the ferromagnetic state, skyrmions appear in the Pt/Co/Ir film, which indicates SAWs create skyrmions (Fig. 1). To clarify the mechanism for the skyrmion creation induced by surface acoustic waves, we performed micromagnetic simulation and found that an inhomogeneous torque arising from surface acoustic waves via the magnetoelastic coupling create a pair of Néel and antiskyrmion-like structure, which subsequently transforms to Néel skyrmion due to the instability of antiskyrmion-like structure in the iDMI systems. In the presentation, we will also talk about our recent simulation study on the skyrmion drive with SAWs.
References
[1] A. Fert, V. Cros and João Sampaio, Nat. Nanotech. 8, 152 (2013). [2] W. Jiang et al., Science 349, 283 (2015). [3] F. Büttner et al., Nat. Nanotech. 12, 1040 (2017).