Room-Temperature van der Waals Perpendicular Ferromagnet Through Interlayer Magnetic Coupling

Ferromagnetic van der Waals (vdW) crystals are promising for future spintronics because they hold huge potential in terms of tunable chemical, mechanical, and physical properties. However, roomtemperature vdW ferromagnets with high-quality perpendicular magnetic anisotropy (PMA) are still elusive, limiting their practical implementations for spintronic applications, such as nonvolatile memories. Here, we show that the magnetic properties of vdW Fe3GeTe2, including the Curie temperature and the PMA, can be tuned by interlayer exchange coupling (IEC). We demonstrate strong ferromagnetic and antiferromagnetic IECs between sputtered Co and vdW Fe3GeTe2 with Pt and Ru spacer layers, respectively. We find that ferromagnetic IEC enhances the Curie temperature of Fe3GeTe2 while maintaining PMA, which can exhibit 100% out-of-plane remanent magnetization above room temperature. On the other hand, antiferromagnetic coupling weakens the PMA, resulting in a multilevel magnetic hysteresis loop of Fe3GeTe2 even at temperatures as small as 10 K. These interlayered coupled 3D/2D heterostructures could emerge as prime candidates for practical vdW spintronic applications.