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

Abstract

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 4 μ_B per unit cell and exhibits an in-plane magnetic easy axis with a magnetic anisotropy energy (MAE) of –1.53 meV/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.