Antiferromagnetic coupling of van der Waals ferromagnetic Fe₃GeTe₂

TLDR

Ferromagnetic 2D van der Waals materials, such as Fe₃GeTe₂ with strong perpendicular anisotropy and a high Curie temperature, are promising for low‑power spintronic devices. First‑principles calculations show that oxide formation at the interface induces antiferromagnetic coupling between Fe₃GeTe₂ and its oxide layer. The study confirms that an oxide layer naturally forms on exfoliated Fe₃GeTe₂ and that antiferromagnetic coupling between the layers produces a tailed hysteresis loop with two‑magnetization reversal curves and negative remanence over a certain temperature range.

Abstract

Among two-dimensional (2D) layered van der Waals materials, ferromagnetic 2D materials can be useful for compact low-power spintronic applications. One promising candidate material is Fe3GeTe2 (FGT), which has a strong perpendicular magnetic anisotropy and relatively high Curie temperature. In this study, we confirmed that an oxide layer (O-FGT) naturally forms on top of exfoliated FGT and that an antiferromagnetic coupling (AFC) exists between FGT and O-FGT layers. From a first-principles calculation, oxide formation at the interface of each layer induces an AFC between the layers. An AFC causes a tailed hysteresis loop, where two-magnetization reversal curves are included, and a negative remanence magnetization at a certain temperature range.