Tuning the Magnetic Anisotropy Energy of MoS₂-supported Mn₁₂ complexes by Electric Field: A First-Principles Study

In this work, we examine low-energy adsorption configurations of four dodecanuclear manganese single-molecule magnets [Mn₁₂O₁₂(O₂CR)₁₆(H₂O)₄] (Mn₁₂), where the ligand R being H, CH₃, CHCl₂ or C₆H₅, on a molybdenum disulfide (MoS₂) monolayer using force field and density functional theory calculations. The van der Waals interaction is shown to be crucial for determining the adsorption energy. Some electrons transfer from the substrate to the molecules upon surface adsorption, resulting in a reduction of the magnetic anisotropy energy of Mn₁₂. Since the lowest unoccupied molecular orbital of Mn₁₂ is close to the valence band of MoS₂, a negative electric field is more effective in modulating charge transfer and energy band alignment, and thus altering the magnetic anisotropy energy, compared with a positive electric field. A significant increase in the magnetic anisotropy energy of Mn₁₂ with the ligand R=CHCl₂ or R=C₆H₅ under a sufficiently high electric field has been predicted. Our calculations show that the molecules remain intact on the surface both before and after the electric field is applied. Finally, a two-level system formed by different adsorption configurations is evaluated, and the tunability of its energy barrier under an electric field is demonstrated. Our study sheds light on tuning the properties of single-molecule magnets using an electric field, when the molecules are supported on a surface.