Layer-Dependent Magnetic Domains in Atomically Thin Fe5GeTe2

Magnetic domain formation in two-dimensional (2D) materials gives perspectives into the fundamental origins of 2D magnetism and also motivates the development of advanced spintronics devices. However, the characterization of magnetic domains in atomically thin van der Waals (vdW) flakes remains challenging. Here, we employ X-ray photoemission electron microscopy (XPEEM) to perform layer-resolved imaging of the domain structures in the itinerant vdW ferromagnet Fe5GeTe2 which shows near room temperature bulk ferromagnetism and a weak perpendicular magnetic anisotropy (PMA). In the bulk limit, we observe the well-known labyrinth-type domains. Thinner flakes, on the other hand, are characterized by increasingly fragmented domains. While PMA is a characteristic property of Fe5GeTe2, we observe a spin-reorientation transition with the spins canting in-plane for flakes thinner than six layers. Notably, a bubble phase emerges in four-layer flakes. This thickness dependence, which clearly deviates from the single-domain behavior observed in other 2D magnetic materials, demonstrates the exciting prospect of stabilizing complex spin textures in 2D vdW magnets at relatively high temperatures. Superscript/Subscript Available

Automated summary

The formation of magnetic domains in two-dimensional materials is of great interest for understanding the fundamental origins of 2D magnetism and for the development of advanced spintronics devices. However, studying magnetic domains in atomically thin van der Waals flakes remains challenging. In this study, layer-resolved imaging of the domain structures in the vdW ferromagnet Fe5GeTe2 was performed using X-ray photoemission electron microscopy (XPEEM). The results showed that the domain structures vary with the thickness of the flakes, indicating the potential of stabilizing complex spin textures in 2D vdW magnets at relatively high temperatures.