Modulation of CoFeB Magnetism via Two-Dimensional van der Waals Fe₃GeTe₂

Abstract

In recent years, two-dimensional van der Waals (2D-vdW) magnets have been widely employed in spintronic devices since they can be reduced to the monolayer while maintaining structural integrity. In this paper, an interfacial effect of the heterostructure including the Co 60 Fe 20 B 20 (CFB) layer and Fe 3 GeTe 2 (FGT) flake is explored. At the Curie temperature (T c ) of FGT, a reduction in the magnetization of the CFB/FGT bilayer is found compared to that of CFB itself unlike at 300 K. It is possible that non-parallel magnetic moments are formed at the interface due to the strong perpendicular magnetic anisotropy (PMA) of magnetic FGT below T c . Using a ferromagnetic resonance technique, we find that both PMA and the magnetic damping of CFB are enhanced by the FGT interface. Particularly, the PMA constant K ⊥ is increased by 20.2% at 300 K, much larger than that at 150 K, which indicates that the enhancement of PMA is induced by orbital hybridization at the interface instead of the magnetic proximity effect. The exchange interaction at the interface for moments between CFB and FGT may play a minor role in the enhancement of PMA of CFB induced by FGT. Also, such a less PMA enhancement at 150 K may be blocked by the magnetic interface of FGT below T c . This research highlights that the magnetism of CFB can be modulated by the interface of FGT even at room temperature, which provides a new approach for the application of 2D-vdW magnets in spintronics.