Multifunctional spin-valley-topological transport and magneto-optical responses in Janus bimetallic CrMnCF2 monolayer

Two-dimensional Janus magnetic materials provide a platform for coupled spin, valley, and magneto-optical phenomena due to broken inversion symmetry. Here we investigate a Janus CrMnCF 2 monolayer using first-principles calculations and Monte Carlo simulations. The calculated results support the thermodynamic, dynamical, and mechanical stability of the CrMnCF 2 monolayer. It exhibits a ferromagnetic ground state with out-of-plane magnetic anisotropy, where Cr and Mn 3 d states dominate the magnetism and induce strong exchange-driven spin splitting. Including spin–orbit coupling, structural asymmetry and ferromagnetism lift the K/K′ valley degeneracy, producing a robust valley splitting of ∼33 meV under biaxial strain (−5% to +5%). Opposite Berry curvature at the two valleys leads to valley-dependent transport and a sizable intrinsic anomalous Hall conductivity of about −130 S/cm under hole doping. In addition, the system exhibits an intrinsic magneto-optical Kerr effect without an external magnetic field, with a maximum Kerr rotation of approximately 130 mdeg in the ultraviolet region. These results highlight CrMnCF 2 as a multifunctional 2D material for spintronic, valleytronic, and magneto-optical applications.