A First-Principles Study on Magnetic Silicene and graphene Quantum Dots

Embedded graphene quantum dots in hydrogenated graphene was found having magnetic characters with triangular and parallelogram. We investigate the magnetic properties of graphene and silicene quantum dots with triangular and parallelogram shapes for both the pure dots and embedded ones in hydrogenated graphene (silicene). It was found that the magnetic properties of the graphene (silicene) dots are determined by the shapes of dots as well as the embedded dots in the hydrogenated graphene. The total magnet moment (in Bohr magneton) of triangular graphene (silicene) dot is nearly root square root of the number of atoms in the dot for both the pure and embedded types. The parallelogram graphene (silicene) dots for both types are antiferromagnetic, except for the graphene dot with eight atoms, it shows as nonmagnetic semiconductor. The HOMO LUMO gap (E_g) of the pure silicene dots is larger than that of embedded ones, nevertheless, oppositely, the E_g of pure graphene dots is about half of that of the embedded one.