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

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)up arrow|L-x|p(z)down arrow > and < p(y)down arrow|L-x|p(z)up arrow > of Te atom and the couplings of < d(x)(2)-(2)(y)up arrow |L-z|d(xy)up arrow > and < d(x)(2)-(2)(y)down arrow|L-z|d(xy)down arrow > of Mn atom. Besides, the ferromagnetism of the Cr2Ge2Te6 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