Tailing the Magnetoelectric Properties of 2H-MoS₂ by Engineering Covalently Bonded Mo Self-intercalation: Ferromagnetic Materials

Two-dimensional (2D) intrinsic ferromagnetic (FM) materials play a crucial role in spintronics. Through a systematic research of the 2H-MoS 2 bilayer (BL) with self-intercalation (SI) of Mo atom, we have discovered that SI can introduce a long-range magnetic order, as Mo SI atoms lose electrons. The MoS 2 BLs (Mo m S n ) with self-intercalated Mo (Mo SI ) atoms show antiferromagnetic (AFM) order under a high concentration of Mo SI atoms, where the direct exchange interaction dominates over the superexchange interaction. Mo m S n becomes half-metal (HM) with interlayer FM order after Mo’s self-intercalation, under lower Mo SI atom concentrations, independent of the stacking orders. Mo 9 S 16 -AA exhibits HM with FM order, with a corresponding Curie temperature ( T c ) of 35 K. Mo m S n -AA and AB stackings with a lower concentration of Mo SI atoms transform into half semiconductors (HSCs). Moreover, the magnetic anisotropy energies (MAEs) of Mo 9 S 16 -AA and AB stackings are −0.080 and −1.06 meV/f.u., suggesting that the magnetic easy axis (EA) of Mo m S n tends to the [100] direction, regardless of the stacking orders. However, the MAEs of Mo m S n -AA and AB stackings differ due to variations in the hybridization interaction between Mo’s d orbitals. The formation energies of Mo m S n change with the chemical potential of S (μ s ) and the concentration of Mo SI atoms. Furthermore, the formation energy (ε f ) monotonically increases as the concentration of Mo SI monotonically increases. Additionally, Mo m S n with Mo SI atoms could be synthesized under a higher chemical potential of Mo atom (μ Mo ). The Mo m S n -AB stackings are always more stable than the AA stackings. Self-intercalated Mo m S n exhibits good dynamic and thermal stability at 300 and 600 K, respectively. These findings suggest a promising approach to introducing a modulated long-range FM order and electromagnetic properties into 2H-MoS 2 and other transition metal dichalcogenides (TMDs).