Understanding ferromagnetism in Ni-doped MoS₂ monolayer from first principles

The electronic and magnetic properties of Ni-doped MoS₂ monolayer have been investigated using the DFT + U method. Two kinds of dopants are considered in the 6 × 6 supercells of MoS₂ monolayer: one Ni substitution for Mo, and two Ni substitutions. Results show that both dopants induce ferromagnetism in MoS₂ monolayer. With a single Ni dopant, the Ni-induced spins on the nearby host atoms are parallel to that on Ni atom through the p-d hybridization, leading to the ferromagnetic (FM) ordering. Two Ni substitutions energetically prefer to cluster together, which makes the FM coupling in the system include (1) the FM p-d hybridization between Ni and neighboring host atoms, and (2) the FM ordering between two Ni atoms due to the Ni(3d)-S(3p)-Ni(3d) superexchange. Efforts have been done to elaborate the favorability for incorporating Ni dopants in MoS₂ monolayer. This work has implications for improving the applications of MoS₂ to spintronic even magneto-optic devices.