First-principles study of the Mn-alloyed Cr2Ge2Te6 monolayer: Intrinsic ferromagnet with robust half-metallicity and large magnetic anisotropy energy

Abstract

Two-dimensional (2D) materials with intrinsic half-metallicity and large magnetic anisotropy energy (MAE) have been a long-sought goal because of potential applications in high-performance spintronics. In this work, using first-principles calculations, we design, investigate and find that the Mn-alloyed Cr₂Ge₂Te₆ monolayer is a half-metal with a considerable in-plane magnetic anisotropy energy (IMAE, 2.276 meV/unitcell) and a high Phase-Transition temperature (Tc/185 K), which is about 3 times higher than that of Cr₂Ge₂Te₆ monolayer without introducing any carriers. Meanwhile, according to the second-order perturbation theory, the IMAE is revealed mainly origin from the couplings of $〈p_y\uparrow \left(L_x\right)p_z\downarrow 〉$ and $〈p_y\downarrow \left(L_x\right)p_z\uparrow 〉$ of Te atom and the couplings of $〈d_{x^2-y^2}\uparrow \left(L_z\right)d_{xy}\uparrow 〉$ and $〈d_{x^2-y^2}\downarrow \left(L_z\right)d_{xy}\downarrow 〉$ of Mn atom. Besides, the ferromagnetism of the CrMnGe₂Te₆ monolayer can be further improved by tensile strains and hole doping. Our findings suggest this monolayer would be a good candidate for spintronic devices and we would provide a strategy for designing the excellent spintronic materials.