Prediction of two-dimensional Dirac materials with intrinsic magnetism, quantum anomalous Hall effect and high Curie temperature

The intrinsic functionality of two-dimensional (2D) materials is crucial for both fundamental studies and practical applications in information processing and storage. In particular, 2D ferromagnets have emerged as a major research field, bringing in new concepts, physical effects, and device designs. More competitive ferromagnetic materials in 2D systems with the quantum anomalous Hall (QAH) state and room-temperature ferromagnetism are much desired. Herein, we predicted stable XC6 (X = V, Nb, and Cu) monolayers through first-principles calculations. Novel topological properties, including the gapless edge state, anomalous hall conductance, Chern number and Berry curvature, were systematically investigated. Without spin-orbit coupling, both VC6 and NbC6 monolayers are ferromagnetic Dirac half-metals, while CuC6 monolayers is a nonmagnetic Dirac semimetal. With spin-orbit coupling, both VC6 and NbC6 monolayers exhibit intrinsic QAH insulators with large out-of-plane magnetocrystalline anisotropy energy and a high Curie temperature of 425 K and 520 K, respectively, and the CuC6 monolayer is a quantum spin Hall (QSH) insulator. Our results provide a promising platform for realizing the QAH and QSH phases and the fantastic integration of Dirac physics, spintronics, and valleytronics. Monolayer NbC6withdouble Dirac points in two different spin channels with and without SOC.