Enhanced Room-Temperature Ferromagnetism in Nanostructured\nMoS<sub>2</sub> Flakes by Hydrogen Post-Treatment: Combined Experimental\nand First-Principles Based Studies

We\nmeticulously studied the individual effects of hydrogen irradiation\nand annealing on the electronic structure and magnetic properties\nof nanostructured MoS<sub>2</sub> thin films grown through chemical\nvapor deposition (CVD). The role of the edge-terminated structure\nand point defects to induce room-temperature ferromagnetism (RTFM)\nis thoroughly investigated. The nanostructured pristine MoS<sub>2</sub> thin films show the formation of a pure 2-H MoS<sub>2</sub> phase,\nconfirmed by X-ray diffraction (XRD) and Raman spectroscopy. Pristine\nMoS<sub>2</sub> thin films are independently annealed in a reducing\nhydrogen environment and irradiated with low-energy hydrogen ions\nto study the significance of point defects such as sulfur vacancies.\nRTFM with a saturation magnetization value (<i>M</i><sub>s</sub>: 1.66 emu/g) has been observed in the pristine film. Magnetization\nincreases after irradiation and annealing processes. However, hydrogen\nannealing at a temperature of 200 °C exhibits a maximum <i>M</i><sub>s</sub> value of 2.7 emu/g at room temperature. The\nincrease in ferromagnetism is attributed to an increment in sulfur\nvacancies, hydrogen adsorption with sulfur, and modification in edges,\nwhich is confirmed by the analysis of an electron probe microanalyzer\n(EPMA), X-ray photoelectron spectroscopy (XPS), and field emission\nscanning electron microscopy (FESEM) measurements. The density functional\ntheory (DFT) calculations have demonstrated that the edge-oriented\nstructure of MoS<sub>2</sub> exhibits a magnetization value of 3.2\nμB. Additionally, introducing an S vacancy and H adsorption\nin a parallel position to the sulfur further enhances the magnetization\nvalue to 3.85 and 3.43 μB, respectively. These findings align\nbroadly with our experimental results.