Magnetic anisotropy energy and effective exchange interactions in Co intercalated graphene on Ir(111)

The electronic structure, magnetic moments, effective exchange interaction parameter and the magnetic anisotropy energy of [monolayer Co]/Ir(1 1 1) and Co intercalated graphene on Ir(1 1 1) are studied making use of the first-principles density functional theory calculations. A large positive magnetic anisotropy of 1.24 meV/Co is found for [monolayer Co]/Ir(1 1 1), and a high Curie temperature of 1190 K is estimated. These findings show the Co/Ir(1 1 1) system is a promising candidate for perpendicular ultra-high density magnetic recording applications. The magnetic moments, exchange interactions and the magnetic anisotropy are strongly affected by graphene. Reduction of the magnetic anisotropy and the Curie temperature are found for graphene/[monolayer Co]/Ir(1 1 1). It is shown that for graphene placed in the hollow-hexagonal positions over the monolayer Co, the magnetic anisotropy remains positive, while for the placements with one of the C atoms on the top of Co it becomes negative. These findings may be important for assessing the use of graphene for magnetic recording and magnetoelectronic applications.