Large even-odd spacing and $g$-factor anisotropy in PbTe quantum dots

TL;DR

This study investigates PbTe quantum dots, revealing large even-odd Coulomb peak spacing, highly anisotropic g-factors, and strong spin-orbit interaction, which are promising for topological quantum computing.

Contribution

It provides the first detailed characterization of PbTe quantum dots, highlighting their large Coulomb blockade spacing and highly anisotropic g-factors related to strong spin-orbit coupling.

Findings

Large even-odd Coulomb peak spacing observed.

Highly anisotropic g-factor tensor with principal values from 0.9 to 22.4.

Strong Rashba spin-orbit interaction inferred from results.

Abstract

PbTe is a semiconductor with promising properties for topological quantum computing applications. Here we characterize quantum dots in PbTe nanowires selectively grown on InP. Charge stability diagrams at zero magnetic field reveal large even-odd spacing between Coulomb blockade peaks, charging energies below 140$~\mathrm{\mu eV}$ and Kondo peaks in odd Coulomb diamonds. We attribute the large even-odd spacing to the large dielectric constant and small effective electron mass of PbTe. By studying the Zeeman-induced level and Kondo splitting in finite magnetic fields, we extract the electron $g$-factor as a function of magnetic field direction. We find the $g$-factor tensor to be highly anisotropic, with principal $g$-factors ranging from 0.9 to 22.4, and to depend on the electronic configuration of the devices. These results indicate strong Rashba spin-orbit interaction in our PbTe quantum dots.