Demonstration of a thickness-step Skyrmion Injector in FeGe*

Magnetic skyrmions have attracted significant research interest over the past decade, both for their intrinsically interesting physical properties, and for their potential as information carriers in novel computing devices [1]. FeGe is one example of a material that hosts skyrmions, which is particularly useful as a test case for skyrmionic devices as the skyrmions are found near room temperature [2]. For any skyrmionic device to prove useful, a reliable method of injecting and removing skyrmions from a defined region of the material is needed. We report the demonstration of such a a skyrmion injector device utilizing electrcic currents applied across a thickness step in FeGe lamella. Our measurements show that in certain temperature and field conditions, skyrmions can be reversibly injected from a thin region of an FeGe Lamella where they exist as an equilibrium state, into a thicker region, where they can only persist as a metastable state. This injection is achieved with a current density of 3 x 10⁸ A / m² which is small relative to the currents required to move magnetic domain walls, and viable for electronic applications. This injector could be used for injecting or removing small numbers of skyrmions into a defined region of a skyrmion hosting material for further manipulation in devices such as skyrmion racetrack memory or reservoir computing, and therefore paves the way for potential future skyrmion applications.

[1] N. Nagaosa and Y. Tokura. Nat. Nanotech. 8, 899 (2013)

[2] X. Z. Yu et al. Nat. Mat. 10, 106 (2011)