Ferromagnetic Weyl semimetals and Quantum Anomalous Hall effect in 2D half-metallic Mn2NT2

Using the first-principles calculations, we predict the 2D monolayer MXene Mn2NT2 (T=-OH, -F, =O) is a half-metallic Weyl semimetal. Without spin–orbit coupling, multiple types Weyl fermions and Fermi arc edge state are observed, and there are abundant topological phases under biaxial strain in the a–b plane. Considering the spin–orbit coupling, the Weyl points are gapped, and the quantum anomalous Hall effect is observed, which is also proved by the chiral edge state in the gap and Chern number. In addition, a tight-binding model is applied to understand the origin of the non-trivial electronic properties of the quantum anomalous Hall phase. Finally, we calculate the Berry curvature and abnormal Hall conductivity of Mn2NT2, and find that they are a non-zero energy point near the Fermi level. Our results indicate that monolayer Mn2NT2 have a potential application in magnetoelectronic devices.