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

TL;DR

This paper models how strong spin-orbit coupling in semiconductor nanowires enhances and makes anisotropic the electron Lande factor, with implications for spintronic applications.

Contribution

The study derives a conduction band Hamiltonian linking the Lande factor tensor to Rashba spin-orbit coupling, including orbital effects, and analyzes anisotropy in InSb nanowires.

Findings

Effective Lande factor is significantly enhanced by spin-orbit interaction.

The Lande factor exhibits twofold anisotropy depending on magnetic field direction.

Anisotropy arises from the interplay between envelope function localization and spin polarization.

Abstract

We investigate the effective Lande factor in semiconductor nanowires with strong Rashba spin-orbit coupling. Using the $\mathbf{k}\cdot\mathbf{p}$ theory and the envelope function approach we derive a conduction band Hamiltonian where the tensor $g^*$ is explicitly related to the spin-orbit coupling constant $\alpha_R$. Our model includes orbital effects from the Rashba spin-orbit term, leading to a significant enhancement of the effective Lande 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 Lande 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.