Exploitable Magnetic Anisotropy of the Two-Dimensional Magnet CrI3

Magnetic anisotropy often plays a central role in various static and dynamic properties of magnetic materials. In particular, for two-dimensional (2D) van der Waals materials, as inferred from the Mermin-Wagner theorem, it is an essential prerequisite for stabilizing ferromagnetic order. In this work, we carry out first-principles calculations for a CrI3 monolayer and investigate how its magnetic anisotropy is interrelated to adjustable parameters governing the underlying electronic structure. We explore various routes for controlled manipulation of magnetic anisotropy: chemical adsorption, substitutional doping, optical excitation, and charge transfer through a heterostructure. In particular, the vertical stacking of CrI3 and graphene is noteworthy in regard to controlling magnetic anisotropy: the spin anisotropy axis is switchable between the out-of-plane and in-plane directions, which is accompanied by a variation in the anisotropy energy of up to 500%. Our results show the possibility that dynamic control of the anisotropy of the 2D magnet CrI3 may enable the development of an advanced spintronic device with enhanced energy efficiency and high operation speed.