Magnetic structure calculations of Ir0.5Mn0.5 over- and sub-layer at Co(001) surface

Density functional theory calculations are performed to investigate the magnetic structure of Ir0.5Mn0.5 chemically alloyed over- and sub-layer at Co(001) surface. Ir0.5Mn0.5 exhibits ferrimagnetic ordering as the ground state for both systems. Alloyed Ir0.5Mn0.5 chemically ordered monolayer is found to be more stable at the surface rather than the sub-surface of Co(001). The magnetic moments of Mn surface atoms, MnI and MnII, in Ir0.5Mn0.5/Co(001) over-layer system are found to be 3.49 μB and −3.56 μB, respectively with intra-layer antiferromagnetic (AFM) coupling. While the MnI couples ferromagnetically with Co subsurface moment (1.68 μB), MnII couples antiferromagnetically. Ir0.5Mn0.5/Co(001) system exhibits a magnetocrystalline anisotropy energy (MAE) of −2.8 meV/cell (−0.7 meV/Mn atom), in the direction along [001]. The ferrimagnetic surface ordering and the high MAE of Ir0.5Mn0.5/Co(001) are believed to be promising for potential applications in perpendicular recording media.