First-principles study on the atomic and electronic structures of graphene-protected magnetic Fe/Ni(111) thin film

Using the first-principles calculations, we investigated the structure dependent magnetic properties of graphene-adsorbed magnetic fcc Fe/Ni(111) thin film. The adsorption sites of the graphene carbon atoms were switched from the fcc hollow sites to the on top sites of the Fe surface atoms due to the fcc Ni(111) substrate effect. From the calculated perpendicular magnetic anisotropy energies, the 1ML-Fe was found to have stable surface-normal magnetization while 2 and 3 monolayer Fe between graphene and Ni(111) had in-plane magnetization. From the electron density of state analyses, the thickness-dependent magnetic anisotropy energy and magnetization direction were found to originate from the shifting of up-spin and down-spin electrons in 3dyz and 3dzx toward higher and lower levels, respectively.