Interface bonding versus strain-induced magnetic anisotropy in epitaxial Fe/semiconductor structures

Abstract

We report measurements of perpendicular magnetic anisotropies of epitaxial Fe/InAs(100) $4\ifmmode\times\else\texttimes\fi{}2$ and Fe/GaAs(100) $4\ifmmode\times\else\texttimes\fi{}6$ films using the polar magneto-optic Kerr effect (MOKE) and of the in-plane magnetic anisotropy, magnetization and g-factor using Brillouin light scattering (BLS). The magnetization is very close to the bulk value in all samples, demonstrating a lack of As intermixing. Both Fe/GaAs and Fe/InAs show large out-of-plane uniaxial surface anisotropy. Both show large in-plane fourfold surface anisotropies which oppose the bulk fourfold anisotropy. Fe/GaAs shows the well known in-plane uniaxial surface anisotropy which is attributed here to interface bonding. However, Fe/InAs shows almost no in-plane uniaxial surface anisotropy, despite the large strain of 5.4% compared to $\ensuremath{-}1.2%$ for Fe/GaAs. The small in-plane uniaxial volume anisotropy which is observed for Fe/InAs is ascribed, due to the thickness dependence, to a magneto-elastic effect.