Measurements of anisotropic g-factors for electrons in InSb nanowire quantum dots

TL;DR

This study measures the anisotropic g-factors in InSb nanowire quantum dots, revealing strong spin-orbit interaction effects and providing detailed tensor characterizations crucial for quantum spintronics applications.

Contribution

It presents the first detailed measurement and analysis of the anisotropic g-factor tensor in InSb nanowire quantum dots, including principal values and orientations.

Findings

g-factor tensor is strongly anisotropic and level-dependent

Determined principal values and axes of the g-factor tensor

Estimated spin-orbit interaction strength as approximately 180 μeV

Abstract

We have measured the Zeeman splitting of quantum levels in few-electron quantum dots (QDs) formed in narrow bandgap InSb nanowires via the Schottky barriers at the contacts under application of different spatially orientated magnetic fields. The effective g-factor tensor extracted from the measurements is strongly anisotropic and level-dependent, which can be attributed to the presence of strong spin-orbit interaction (SOI) and asymmetric quantum confinement potentials in the QDs. We have demonstrated a successful determination of the principal values and the principal axis orientations of the g-factor tensors in an InSb nanowire QD by the measurements under rotations of a magnetic field in the three orthogonal planes. We also examine the magnetic-field evolution of the excitation spectra in an InSb nanowire QD and extract a SOI strength of $\Delta_{so}\sim 180$ $\mu$eV from an avoided level crossing between a ground state and its neighboring first excited state in the QD.