Orbital contributions to the electron g-factor in semiconductor nanowires

TL;DR

This paper investigates how orbital effects significantly enhance the electron g-factor in semiconductor nanowires, explaining recent experimental observations of unexpectedly large g-factors.

Contribution

It demonstrates that orbital contributions and LS coupling in higher subbands can greatly increase the g-factor, supported by simulations for InAs and InSb nanowires.

Findings

Orbital effects can enhance the g-factor by an order of magnitude.

The enhancement persists even with broken cylindrical symmetry.

Large anisotropy in g-factor under magnetic field rotation is predicted.

Abstract

Recent experiments on Majorana fermions in semiconductor nanowires [Albrecht et al., Nat. 531, 206 (2016)] revealed a surprisingly large electronic Land\'e g-factor, several times larger than the bulk value - contrary to the expectation that confinement reduces the g-factor. Here we assess the role of orbital contributions to the electron g-factor in nanowires and quantum dots. We show that an LS coupling in higher subbands leads to an enhancement of the g-factor of an order of magnitude or more for small effective mass semiconductors. We validate our theoretical finding with simulations of InAs and InSb, showing that the effect persists even if cylindrical symmetry is broken. A huge anisotropy of the enhanced g-factors under magnetic field rotation allows for a straightforward experimental test of this theory.