Structural and magnetic properties of Fe-membranes embedded in hexagonal graphene nanoholes

Abstract

The structure and magnetism of Fe-doped hexagonal graphene nanoholes (h-GNHs) were studied on the basis of density-functional theory. The nonzero magnetic moment of carbon in zigzag edge can be greatly reduced in Fe-doped h-GNHs due to the local CFe interaction. The reduced magnetic moment is almost zero, and its direction is opposite to that of iron atoms. Therefore, Fe-adsorption may be used to destroy the spin polarization of graphene zigzag edge. In Fe-doped h-GNHs, iron atom would prefer to adsorb on graphene armchair edge and form five-member (1Fe + 4C) ring. In stable Fe-doped h-GNHs, the bond length of CFe is about 1.9 Å. And in the most stable Fe-membrane embedded h-GNH with the largest binding energy, the average FeFe bond length is about 2.36 Å. Besides, the mean magnetic moment induced by iron atoms changes greatly from 1.45 μB per iron atom to 3.46 μB per iron atom in Fe-doped h-GNHs. The magnetism of iron seems to be sophisticated. It is related to the type of graphene edge, the size of GNH and the number of iron atoms.