Enhancement and anisotropy of electron Landé factor due to spin-orbit interaction in semiconductor nanowires

We investigate the effective Landé factor in semiconductor nanowires with strong Rashba spin-orbit coupling. Using the $k·p$ theory and the envelope function approach we derive a conduction band Hamiltonian where $g^{*}$ is explicitly related to the spin-orbit coupling constants ${\alpha }_R$. Our model includes orbital effects from the Rashba spin-orbit term, leading to a significant enhancement of the effective Landé factor which is naturally anisotropic. For nanowires based on the low-gap, high spin-orbit coupled material InSb, we investigate the anisotropy of the effective Landé factor with respect to the magnetic field direction, exposing a twofold symmetry for the bottom gate architecture. The anisotropy results from the competition between the localization of the envelope function and the spin polarization of the electronic state, both determined by the magnetic field direction.