LAUSR

The two-dimensional electron system in $(110)\phantom{\rule{4pt}{0ex}}{\mathrm{Al}}_{2}{\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}}/{\mathrm{SrTiO}}_{3}$ heterostructures displays anisotropic electronic transport. Largest and lowest conductivity and electron mobility $\ensuremath{\mu}$ are observed along the [001] and $[1\overline{1}0]$ directions, respectively. The anisotropy of the sheet resistance and $\ensuremath{\mu}$ likewise leads to a distinct anisotropic normal magnetotransport (MR) for $Tl30\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. However, at temperatures $Tl5\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ and magnetic field $Bl2\phantom{\rule{0.28em}{0ex}}\mathrm{T}\phantom{\rule{0.28em}{0ex}}\mathrm{MR}$ is dominated by weak antilocalization. Despite the rather strong anisotropy of the Fermi surfaces, the in-plane anisotropic magnetoresistance (AMR) displays twofold noncrystalline anisotropy. However, the AMR amplitude is found to be anisotropic with respect to the current direction, leading to a 60% larger AMR amplitude for current $I$ along the [001] direction compared to $I$ parallel to $[1\overline{1}0]$. Tight-binding calculations evidence an anisotropic Rashba-induced band splitting with dominant linear $k$ dependence. In combination with semiclassical Boltzmann theory, the noncrystalline AMR is well described, despite the anisotropic Fermi surface.