Uniaxial magnetic anisotropy in Fe/GaAs(001): Role of magnetoelastic interactions

Abstract

The origin of the in-plane uniaxial magnetic anisotropy of epitaxial $\mathrm{Fe}(001)$ films on $\mathrm{GaAs}(001)$ has been controversially attributed either to a magnetoelastic interaction or to oriented interface bonds. In order to check the relevance of magnetoelastic contributions we performed magneto-optic Kerr effect (MOKE) and magnetoelastic stress measurements on $\mathrm{Fe}(001)$ and ${\mathrm{Fe}}_{32}{\mathrm{Co}}_{68}(001)$ bcc epitaxial films on $\mathrm{GaAs}(001)$ in a thickness range from several monolayers (ML) up to 100 ML. The magnetoelastic coupling coefficient ${B}_{2}$ of 30 ML films is $+(8.4\ifmmode\pm\else\textpm\fi{}1.4)\phantom{\rule{0.16em}{0ex}}{\mathit{MJ}/\mathrm{m}}^{3}$ for $\mathrm{Fe}(001)$ and $\ensuremath{-}(23.2\ifmmode\pm\else\textpm\fi{}3.7)\phantom{\rule{0.16em}{0ex}}{\mathit{MJ}/\mathrm{m}}^{3}$ for ${\mathrm{Fe}}_{32}{\mathrm{Co}}_{68}(001)$, respectively. In spite of the opposite sign of ${B}_{2}$ for $\mathrm{Fe}$ and ${\mathrm{Fe}}_{32}{\mathrm{Co}}_{68}$, the same sign of the uniaxial anisotropy constant ${K}_{U}^{\mathrm{eff}}$ is experimentally observed. It is concluded that the magnetoelastic interaction is not the dominating contribution to the uniaxial magnetic anisotropy in these systems.