Thickness effect on magnetocrystalline anisotropy of MnPt(0 0 1) film

We investigated the magnetocrystalline anisotropy (MCA) of MnPt(0 0 1) film and MnPt/MgO(0 0 1) using ab initio electronic structure calculations. We found that the magnetic ground state of the MnPt film strongly depends on thickness (n). In bulk and in film with n ≥ 7 monolayers; AFM-II is the magnetic ground state. However, as the film thickness reduces, the magnetic ground state shifts from AFM-II to AFM-III. We employ layer-by-layer Heisenberg model to explain thickness dependent ground state transition. AFM-III state in the Mn-terminated film shows large perpendicular MCA(PMCA), which further enhances on a MgO(0 0 1) substrate. We conclude that the interface plays a key role for the enhancement of PMCA on the substrate.