Tailorable magnetocrystalline anisotropy at the MnPt3(001) surface

Abstract

We report results of the density functional theory and density functional perturbation theory calculations on thermodynamic stability, magnetic structure, and magnetocrystalline anisotropy (MCA) of a ${\mathrm{MnPt}}_{3}(001)$ thin film. It is predicted that the magnetic ground state of the Pt-terminated ${\mathrm{MnPt}}_{3}$(001) thin films is the ferromagnetic as found in its bulk structure, while the MnPt termination favors the A-type antiferromagnetic order at the surface. Even more drastic effect of the surface termination on MCA is revealed; in contrast to an in-plane magnetization preferred for the MnPt termination, the Pt-terminated ${\mathrm{MnPt}}_{3}$(001) thin films exhibit an extremely large perpendicular MCA (PMCA) up to an order of 10 erg/${\mathrm{cm}}^{2}$ regardless of its film thickness. Moreover, from detailed single-particle energy spectra analyses, this magnetization reversal is mainly determined by an interplay between two in-plane orbital states, ${d}_{\text{xy}}$ and ${d}_{{\text{x}}^{2}\ensuremath{-}{\text{y}}^{2}}$ states, of the Pt atom with induced magnetism at the surface, as a result of their energy level changes associated with the Mn $3d\ensuremath{-}\mathrm{Pt}\phantom{\rule{4pt}{0ex}}5d$ hybridization. This reported thin-film system can act as a prototype for the in-depth study of the importance of the surface termination with large perpendicular magnetocrystalline anisotropy in spintronic applications.