LAUSR

Transition-metal dichalcogenides (TMDCs) stand out with their high chemical stability and the possibility to incorporate a wide range of atoms and molecules between the layers. The behavior of conduction electrons in such $3d$-metal-inserted materials is closely related to their magnetic properties and can be sensitively controlled by external magnetic fields. Here, we study the magnetotransport properties of Mn-inserted $\mathrm{Nb}{\mathrm{S}}_{2}, {\mathrm{Mn}}_{1/4}\mathrm{Nb}{\mathrm{S}}_{2}$, demonstrating a complex behavior of the magnetoresistance and of the ordinary and anomalous Hall resistivity. Application of high pressure as tuning parameter leads to the drastic changes of the magnetotransport properties of ${\mathrm{Mn}}_{1/4}\mathrm{Nb}{\mathrm{S}}_{2}$ exhibiting large negative magnetoresistance up to $\ensuremath{-}65%$ at 7.1 GPa. First-principles electronic structure calculations indicate a pressure-induced transition from a ferromagnetic to antiferromagnetic state. Theoretical calculations accounting for the finite temperature magnetic properties suggest a field-induced metamagnetic ferromagnetic-antiferromagnetic transition as an origin of the large negative magnetoresistance. These results inspire the development of materials for spintronic applications based on $3d$-element-inserted TMDCs with a well controllable metamagnetic transition.