Reversible Tuning of the Ferromagnetic Behavior in Mn-Doped MoS₂ Nanosheets via Interface Charge Transfer

Reversible manipulation of the magnetic behavior of two-dimensional van der Waals crystals is crucial for expanding their applications in spin-based information-processing technologies. However, to date, most experimental approaches to tune the magnetic properties are single way and have very limited practical applications. Here, we report an interface charge-transfer method for obtaining a reversible and air-stable magnetic response at room temperature in Mn-doped MoS₂ nanosheets. By adsorption of benzyl viologen (BV) molecules as the charge donor, the saturation magnetization of Mn-doped MoS₂ nanosheets is enhanced by a magnitude of 60%, and the magnetization can be restored to the original value when the adsorbed BV molecules are removed. This cycle can be repeated many times on the same sample without detectable degradation. Experimental characterizations and first-principles calculations suggest that the enhanced magnetization can be attributed to the increase of Mn magnetic moment because of the enriched electrons transferred from BV molecules. This work shows that interface charge transfer may open up a new pathway for reversibly tuning the exchange interactions in two-dimensional nanostructures.