Highly Enhanced robust room temperature ferromagnetism in CVD-grown nano-dimensional MoS2 flakes by modifying edges and defect engineering

Abstract: The alterations in the magnetic properties and electronic structure of chemical vapor deposition (CVD) grown nano-dimensional molybdenum disulfide (MoS2) after low energy ion irradiation are thoroughly investigated. The formation of pure hexagonal 2-H phase has been identified by Raman spectroscopy and X-ray diffraction (XRD). The pristine samples are irradiated by Argon (Ar) ions with low energy at different fluences. A comprehensive analysis of Raman spectroscopy data manifests the formation of lattice defects like S-vacancies across the samples after irradiation. Triangular-flake formation in the pristine sample is confirmed by field emission scanning electron microscopy (FESEM) images. After increasing irradiation fluences the big flakes commenced to fragment into smaller ones enhancing the number of edge-terminated structures. The electron probe microanalyzer (EPMA) analysis verifies the absence of any magnetic impurity. Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS) study confirm the formation of S-vacancies after irradiation. The pristine sample exhibits diamagnetic behavior at room temperature. The saturation magnetization value increases with increasing the ion irradiation fluences, and the sample irradiated with 1e15 ions/cm2 demonstrates the highest magnetization value of 4.18 emu/g. The impact of edge-terminated structure and point defects like S-vacancies to induce room-temperature ferromagnetism (RTFM) is thoroughly examined.