Indirect exchange interaction between magnetic adatoms in a monolayer MoS2

We study the Ruderman-Kittle-Kasuya-Yosida (RKKY) interaction in a monolayer MoS${}_2$. We show that the rotation of the itinerant electron spin due to the spin-orbit coupling causes a twisted interaction between two magnetic adatoms which consists of different RKKY coupling terms, the Heisenberg, Dzyaloshinsky-Moriya and Ising interactions. We find that the interaction terms are very sensitive to the Fermi energy values and change dramatically from doped to undoped systems. A finite doping causes that all parts of the interaction oscillate with the distance of two magnetic impurities, $R$ and the interaction behaves like $R^{-2}$ for the long distance between two localized spins. We explore a beating pattern of oscillations of the RKKY interaction which occurs for the doped system.