Electronic structure of substitutionally Mn-doped graphene

The electronic structure and magnetism of manganese (Mn)-doped graphene has been studied using the density functional theory. It was found that the electronic structure was sensitive to the value of the on-site energy for the Mn 3d orbital. Thus, it was crucial to accurately account for the electron correlation in the calculation. By using the self-consistent U method, we were able to determine the specific U value in this chemical environment to be 5.39 eV, and we found that the system is a charge transfer insulator with a bandgap of about 0.2 eV. The Mn strongly binds with the carbon atoms, causing the localization of the pi orbital near the Fermi level. The crystal field splits the Mn d orbitals and leads to 3.00 mu(B) magnetic moment at the ground state. The Mn-doped graphene acquires macroscopic antiferromagnetism when the doping density reaches a threshold between 3 and 5%.