Structures and Magnetic Properties of MoS2 Grain Boundaries with Antisite Defects

Monolayer molybdenum disulfide (MoS2), a two-dimensional semiconductor, possesses extraordinary physical properties and holds great promise for electronics,optoelectronics, and optics. However, the synthetic MoS2 samples usually comprise substantial structural defects, which greatly affect the device performance. Herein we comprehensively explore the atomic structures, energetic stability, and electronic and magnetic properties of grain boundaries (GBs) in monolayer MoS2 as well as the GBs decorated by antisite defects by first principles calculations. Eighteen types of GBs each carrying five kinds of antisite defects (a total of 108 defective systems) are constructed. The stability and magnetic properties of these defective monolayers are closely related, to the type and number of homoelemental bonds. The GBs dominated by one type of homoelemental bond are ferromagnetic and have intrinsic magnetic moments up to 1.10 mu(B)/nm. The GBs with equal number of defect rings that involve Mo-Mo and S-S bonds can exhibit antiferromagnetic behavior. Formation of antisite defects on the MoS2 GBs is much more favored than that in perfect monolayer, and the antisite defects do not severely affect the magnetic properties of the GB systems. Our theoretical results provide vital, guidance for modulating the magnetic properties of monolayer transition metal dichalcogenides by defect engineering.