Tuning quantum anomalous Hall effect in ferromagnetic 1T-CrX2 (X = Bi, Sb) monolayers

In this work, we have investigated the emergence of quantum anomalous Hall (QAH) effect in 1T-CrX2 (X = Bi, Sb) monolayers. Using a combination of first-principles and tight-binding methods, we demonstrate that the topological phase is a result of biaxial tensile strain, many-electron effects, and spin–orbit coupling. Both two-dimensional structures are ferromagnetic under strain and the phase transition from trivial to QAH is identified by nonvanishing Berry curvature with a Chern number C=2. The many-electron effects, expressed here by an effective Coulomb U parameter, play an important role in the magnetic anisotropy energy, affecting the QAH phase. Our results show that the 1T-CrX2 monolayers support large deformations, up to 25% of biaxial tensile strain, keeping their electronic, magnetic, and topological properties. This large elasticity combined with the bulk-boundary topological states, makes these 2D magnetic structures feasible to adhere on distinct surfaces being potential for spintronic applications.