Tunable magnetic anisotropy in two-dimensional CrX3/AlN (X= I,Br,Cl) heterostructures

Controlling the magnetic anisotropy of two-dimensional (2D) ferromagnets (FMs) is of great importance for the development of next generation spintronics. Here, by combining the 2D FM chromium trihalides CrX3 (X=I,Br,Cl) monolayer (ML) with the fully hydrogenated bilayer AlN (AlN-2L) together, the electronic and magnetic properties, especially the magnetic anisotropies, of CrX3/AlN heterostructures (CrX3 HSs) are systematically investigated based on first-principles calculations. When the polarization direction of AlN-2L reverses, the magnetic easy axis of CrX3 MLs can be switched between out-of-plane and in-plane directions. Particularly the magnetic anisotropic energy is tuned by a maximum of 200% variation in CrI3/AlN. It is shown that the different effects of AlN-2L on the modulation of the magnetic easy axis of CrX3 MLs are related to their different interfacial charge transfer/redistribution across their interfaces. In addition, a transition from FM semiconductor to half-metal is found in all CrX3 MLs when the polarization direction points toward CrX3 MLs. Our results suggest a feasible avenue for the design of van der Waals HSs to realize the control of magnetic anisotropy in 2D FMs.