Room temperature ferromagnetism in Mn-doped silicon carbide from first-principles calculations

Using density functional theory ab initio calculations, we study magnetic moments and ordering temperatures of Mn-doped 3C and 4H polytypes of silicon carbide (SiC) with the Mn impurities substituting at different lattice sites. For an improved accuracy of the Curie temperature (T(C)) and magnetic moment estimations, compared to earlier studies, the computational approach includes calculations of the equilibrium atomic positions, i.e. accounts for impurity-substitution-caused crystal lattice relaxation, individually for both the ferromagnetic and antiferromagnetic states of SiC-Mn. Additionally, for the various supercell configurations studied, the total energy calculations are done using optimized equilibrium supercell volumes, corresponding to the minima of the total energy-supercell volume relationships. Calculations show that the Curie temperature is expected to be above room temperature in most of the supercell configurations studied. Dependence of T(C) on the distance between Mn atoms is shown to be nonmonotonic, depending strongly on the spatial distribution of Mn electronic orbitals for substitution at the different sites. The results allow us to suggest that SiC-Mn diluted magnetic semiconductors are a promising choice for room temperature spintronics applications.