Strong edge-induced ferromagnetism in sputtered MoS2 film treated by post-annealing

We report edge-induced ferromagnetism in a sputtered molybdenum disulfide (MoS2) film having a long whole-edge length, with the effects of crystallinity improvement including edge reconstruction by sulfur vapor and argon annealing. Strong edge-induced ferromagnetism was observed by annealing, and its saturation magnetization of 13–26 emu/cc was larger than that of a chemical-vapor deposition sample with edge-induced ferromagnetism, as reported previously. Whereas both the annealing steps improved the crystallinity of the sputtered MoS2 film, argon annealing significantly enhanced the ferromagnetism. We conclude that the difference of the ferromagnetism enhancement between the sulfur and argon annealing steps is attributed to the edge reconstruction shape, which depends on the sulfur chemical potential.