Magnetic properties of graphene/BN/Co(111) and potential spintronics

• The adsorption energy is greatly enhanced due to buckling of supporting BN layer.
• The graphene has a gap only in one spin band.
• The Co shows a half metallic state.
• Due to the gap in graphene and half metallic feature of Co, a high TMR ratio is expected.

Using the Vienna ab initio simulation package (VASP) we have explored structural, adsorption, and magnetic properties of graphene/BN/Co(111) with the help of semi empirical and non-local van der Waals functional methods such as DFT-D2, vdW-DF2, optPBE-vdW, and optB88-vdW. In the most stable optimized structure, one carbon is on top of B atom and the other carbon is on top of hollow site of BN layer. No buckling geometry is found in both graphene and BN layers with vdW-DF2 method. In contrast, all three other approaches show that a buckling feature takes place in BN layer adjacent to Co substrate and due to this buckling an adsorption energy of graphene is significantly enhanced. Very interestingly, the graphene has an energy gap only in one spin band due to the influence of Co and an insulating state in BN layer adjacent to graphene is observed. In addition, the Co layer displays half metallic states as well. This feature suggests that the graphene/BN/Co(111) can be utilized for ideal tunneling magnetoresistance (TMR) structure because a high TMR ratio is expected.