Demonstration of Controlled Skyrmion Injection Across a Thickness Step

Spintronic devices
incorporating magnetic skyrmions have
attracted
significant interest recently. Such devices traditionally focus on
controlling magnetic textures in 2D thin films. However, enhanced
performance of spintronic properties through the exploitation of higher
dimensionalities motivates the investigation of variable-thickness
skyrmion devices. We report the demonstration of a skyrmion injection
mechanism that utilizes charge currents to drive skyrmions across
a thickness step and, consequently, a metastability barrier. Our measurements
show that under 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 × 108 A m–2, nearly 3 orders of magnitude lower than required to move magnetic
domain walls. This highlights the possibility to use such an element
as a skyrmion source/drain within future spintronic devices.