Correlation between tetragonal zinc-blende structure and magnetocrystalline anisotropy of MnGa epilayers on GaAs(111)

Abstract MnGa films of few nanometer thickness with tetragonal zinc-blende (TZB) structure were grown by molecular beam epitaxy on GaAs(111) substrates. These ultrathin films have high magnetization at room temperature with magnetic moment as high as 3.2 μ B per formula unit. A strong magnetocrystalline anisotropy energy (MAE) comparable to that reported to δ -MnGa films with body-centered tetragonal (BCT) structure with similar c / a =1.1 is observed. Electronic structure calculations using density functional theory (DFT) reveal a robust ferrimagnetic ground state at room temperature and confirm that zinc-blende structure with tetragonal distortion has a metastable character. The strong MAE is associated with anisotropy of orbital magnetic moment which is described by the symmetry of the spin-polarized charge density along the crystallographic axes.