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

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 mu(B) per formula unit. A strong magnetocrystalline anisotropy energy (MAE) comparable to that reported to delta-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. (C) 2014 Elsevier By. All rights reserved.