Theoretical insight into the unique dual roles of Li doping in switching magnetic anisotropy and enhancing Curie temperature in CoCl3 monolayers.

Two-dimensional (2D) magnetic materials have attracted significant attention due to their potential applications in spintronic and nanoscale devices. In this work, we investigate the electronic and magnetic properties of a CoCl3 monolayer using first-principles calculations. The pristine CoCl3 monolayer is found to be a magnetic semiconductor with a total magnetic moment of 4µB per unit cell and exhibits an in-plane magnetic easy axis with a magnetic anisotropy energy (MAE) of -1.53 meV per Co. To achieve a more desirable out-of-plane magnetization orientation for spintronic applications, we propose electron doping via alkali Li atoms placed at hollow sites. Our results reveal that Li doping effectively modulates the spin-orbit coupling environment, resulting in a switch of the easy axis from in-plane to out-of-plane. At a Li-Co2Cl6 ratio of 1 : 1, the MAE increases to 0.75 meV per Co atom, and the Curie temperature is enhanced from 28 K to 61 K. This study is expected to advance the fundamental understanding of two-dimensional ferromagnetic materials and to inspire new approaches for tailoring their properties toward nanodevice integration.