Strain-induced magnetic anisotropies in Co films on Mo(110)

Abstract

$\mathrm{Mo}∕\mathrm{Co}(0001)∕\mathrm{Mo}(110)$ epitaxial films were grown by molecular beam epitaxy in ultrahigh vacuum on $(11\overline{2}0)$ oriented $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ substrates. Co grows on Mo(110) in the Nishiyama-Wassermann orientation, i.e., $[1\overline{1}00]\mathrm{Co}\ensuremath{\Vert}[1\overline{1}0]\mathrm{Mo}$. Low energy electron diffraction reveals a lateral expansive strain of the Co film independent of the thickness. Magnetic anisotropies were obtained from hard-axis magnetization loops measured by Kerr magnetometry in longitudinal and polar geometry. Magnetic interface anisotropies are very small $(<0.04\phantom{\rule{0.3em}{0ex}}\mathrm{mJ}∕{\mathrm{m}}^{2})$. Deviations of the volume-type in-plane $({K}_{v,p}=0.79\phantom{\rule{0.3em}{0ex}}\mathrm{MJ}∕{\mathrm{m}}^{3})$ and out-of-plane $({K}_{v}=\ensuremath{-}9.5\phantom{\rule{0.3em}{0ex}}\mathrm{MJ}∕{\mathrm{m}}^{3})$ anisotropies from bulk values for hexagonal-close-packed Co are attributed to magnetoelastic anisotropies.