Efficient spin injection and giant magnetoresistance in Fe/MoS${}_2$/Fe junctions

We demonstrate giant magnetoresistance in Fe/MoS${}_2$/Fe junctions by means of $\mathit{\text{ab-initio}}$ transport calculations. We show that junctions incorporating either a mono- or a bi-layer of MoS${}_2$ are metallic and that Fe acts as an efficient spin injector into MoS${}_2$ with an efficiency of about 45%. This is the result of the strong coupling between the Fe and S atoms at the interface. For junctions of greater thickness a maximum magnetoresistance of $\sim$300% is obtained, which remains robust with the applied bias as long as transport is in the tunneling limit. A general recipe for improving the magnetoresistance in spin valves incorporating layered transition metal dichalcogenides is proposed.