Mn-doped graphene is investigated using first-principles calculations based on the density functional theory （DFT）. The magnetic moment is calculated for systems of various sizes, and the atomic populations and the density of states （DOS） are analyzed in detail. It is found that Mn doped graphene-based diluted magnetic semiconductors （DMS） have strong ferromagnetic properties, the impurity concentration influences the value of the magnetic moment, and the magnetic moment of the 8×8 supercell is greatest for a single impurity. The graphene containing two Mn atoms together is more stable in the 7×7 supercell. The analysis of the total DOS and partial density of states （PDOS） indicates that the magnetic properties of doped graphene originate from the p–d exchange, and the magnetism is given a simple quantum explanation using the Ruderman–Kittel–Kasuya–Yosida （RKKY） exchange theory.
Field-effect transistors （FETs） for logic applications, graphene and MoS2, are discussed. These materials have based on two representative two-dimensional （2D） materials, drastically different properties and require different consider- ations. The unique band structure of graphene necessitates engineering of the Dirac point, including the opening of the bandgap, the doping and the interface, before the graphene can be used in logic applications. On the other hand, MoS2 is a semiconductor, and its electron transport depends heavily on the surface properties, the number of layers, and the carrier density. Finally, we discuss the prospects for the future developments in 2D material transistors.
