Designing a functionalized 2D-TMD (MoX2, X = S, Se) hosting half-metallicity for selective gas-sensing applications: Atomic-scale study

Half metallicity is a desirable property not only for spintronic devices but also for selective gas sensing applications. The scope of the present investigation is to search/design transition-metal TM doped transition-metal dichalcogenide TMD monolayers (MoX2, X = S, Se) that can host half-metallicity. The screening of various TMs, using spin-polarized DFT calculations, yielded positive results on (Mn, Fe, and Ni)-doped MoS2 MLs and (V, Mn, Fe, and Co)-doped MoSe2 to host half-metallicity when smaller samples of sizes 4 x 4, 5 x 5, and 6 x 6 primitive cells (PCs) are considered. The half-metallicity disappears for larger samples. The origin of this phenomenon can be attributed to the existence of ferromagnetic-coupling (FMC) interactions, governing the groundstate, involving the TM-dopant with its six mirror images, formed by the periodic-boundary conditions. The disappearance of half metallicity is also associated with a drastic change in magnetization vertical bar Delta M vertical bar >> 0). The critical length for the existence of FMC is found to be dependent on both the host crystal and the type of magnetic impurity; at the average is of the order of Lc similar to 20 angstrom. Furthermore, we investigated the relevance of half-metallicity to gas-sensing applications (e.g., specifically, MoSe2:Mn ML was taken as an example). In this latter particular case, our results showed the half-metallicity to be a useful property that can be explored for selective gas-sensing of NO2 gas molecules. Our theoretical results are benchmarked to the available data in literature and found to be in good agreement with them.

Automated summary

The aim of this study is to search/design transition-metal TM doped transition-metal dichalcogenide TMD monolayers that can exhibit half-metallicity. The investigation showed positive results on (Mn, Fe, and Ni)-doped MoS2 MLs and (V, Mn, Fe, and Co)-doped MoSe2 in smaller sample sizes of 4 x 4, 5 x 5, and 6 x 6 primitive cells. The disappearance of half metallicity in larger samples can be attributed to the existence of ferromagnetic-coupling interactions and a drastic change in magnetization.