  Density functional theory is used to explore the possibility of inducing
impurity band ferromagnetism in monolayers of semiconducting MoS2 by
introducing holes into the narrow Mo 4d band that forms the top of the valence
band. A large out of plane anisotropy is found for unpaired spins bound to the
substitutional acceptor impurities V, Nb and Ta that couple ferromagnetically
for all but the shortest separations. Using the separation dependent exchange
interactions as input to Monte Carlo calculations, we estimate ordering
temperatures as a function of the impurity concentration. For about 9% of V
impurities, Curie temperatures in excess of 160 K are predicted. The singlet
formation at short separations that limits the ordering temperature is
explained and we suggest how it can be circumvented.
