  We study current-induced deterministic magnetization switching and domain
wall motion via polar Kerr microscopy in all-amorphous
W$_{66}$Hf$_{34}$/CoFeB/TaO$_\text{x}$ with perpendicular magnetic anisotropy
and large spin Hall angle. Investigations of magnetization switching as a
function of in-plane assist field and current pulse-width yield switching
current densities as low as $3\times 10^{9}$ A/m$^2$. We accredit this low
switching current density to a low depinning current density, which was
obtained from measurements of domain wall displacements upon current injection.
This correlation is verified by investigations of a Ta/CoFeB/MgO/Ta reference
sample, which showed critical current densities of at least one order of
magnitude larger, respectively.
