Interfacial magnetic coupling in Co/antiferromagnetic van der Waals compound FePS₃

In this study, a Co-thin film was deposited on the van der Waals compound of FePS₃ for the investigation of interfacial magnetic coupling, which is crucial to the application in spintronic devices. As characterized by atomic force microscopy, the exfoliated FePS₃ surface was composed of defects within ±1 monolayer height. The Co thin film covered the FePS₃ substrate uniformly with a roughness within ±0.5 nm. The 2 nm-Pd/7 nm-Co/FePS₃ exhibited isotropic magnetism in the surface plane and the magnetic coercivity drastically decreased by more than 50% when the temperature was elevated from 85 K to 110–120 K, which is nearly the Néel temperature of FePS₃. This observation indicates the interfacial magnetic coupling between Co and FePS₃. The Co/FePS₃ magnetic coupling is robust even after annealing up to 200 °C. Furthermore, the measurement of X-ray magnetic circular dichroism confirmed the presence of non-compensated Fe moment along the in-plane direction is parallel to the Co magnetization direction. The net Fe-moment is supposed to play an essential role in mediating the magnetic coupling between the in-plane ferromagnetic Co and the perpendicular antiferromagnetic FePS₃.