Controllable Antiferromagnetic-Ferromagnetic phase transition in monolayer MnPSe3 via atomic adsorption of Li, O, and F

Abstract: The engineering of magnetic order and electronic states in two-dimensional (2D) materials is pivotal for advanced spintronic technologies. Despite their potential, the scarcity of intrinsic 2D ferromagnets remains a critical challenge. Here, we employ density functional theory with Hubbard-U corrections to systematically investigate adsorbate-driven magnetic transitions in monolayer MnPSe3. While pristine MnPSe3 exhibits antiferromagnetic (AFM) ordering with a semiconducting gap, Li, O, and F adatom adsorption induces an AFM-to-ferromagnetic (AFM-FM) phase transition across large coverage ranges. Our calculations reveal enhanced thermodynamic stability at elevated coverages, with full-coverage configurations (Li0.5MnPSe3, MnPSe3O0.5, MnPSe3F0.5) favored energetically. Hybrid functional (HSE06) calculations show that F adsorption drives a semiconductor-to-half-metal transition, whereas Li and O adsorption preserves semiconductivity. Moreover, Li adsorption induces a valley splitting of 20.3 meV at the K1 and K2 points in the band structure of the monolayer MnPSe3. Magnetic anisotropy analysis reveals adsorbate-dependent easy-axis reorientation: Li (electron doping) switches the easy-axis from in-plane to out-of-plane, while O/F (hole doping) stabilizes in-plane easy-axis, consistent with carrier-density-modulation simulations. Crucially, carrier doping results indicate that once the electron doping concentration reaches critical concentration, the magnetic easy axis of monolayer MnPSe3 transitions from in-plane to out-of-plane. This work establishes atomic adsorption as a robust strategy for tailoring 2D magnetism, resolving discrepancies through rigorous treatment of exchange-correlation effects and configurational diversity.