Creation of magnetic skyrmions by surface acoustic waves in Pt/Co/Ir trilayer films

A magnetic skyrmion, a particle-like noncoplanar topological spin structure characterized by a nonzero topological integer called the skyrmion number, has great potential for various spintronic applications. In particular, efficient and practical means to create skyrmions is an important technological issue. However, creation of skyrmions has been achieved by only using currents so far, and moreover, in these methods, the skyrmions are only created at a specific position in the films.
In this presentation, we demonstrate a novel approach for skyrmion creation by employing surface acoustic waves (SAWs); in asymmetric multilayers of Pt/Co/Ir, we experimentally observed at room temperature that skyrmions can be created by propagating SAWs in a wide area of the magnetic film due to the long propagation length of SAWs. Micromagnetic simulation reveals inhomogeneous torque arising from both SAWs and thermal fluctuations creates a pair of Néel and antiskyrmion-like structure, which subsequently transforms to Néel skyrmion due to the instability of antiskyrmion-like structure in systems with interfacial Dzyaloshinskii-Moriya interaction. Our finding provides a novel guiding principle for efficient manipulation of topological spin objects without Joule heating dissipation.