Strong g-Factor Anisotropy in Hole Quantum Dots Defined in Ge/Si Nanowires

TL;DR

This paper reports the creation of tunable hole quantum dots in Ge/Si nanowires, revealing a highly anisotropic g-factor that depends on magnetic field orientation, advancing quantum dot control in nanostructures.

Contribution

It introduces a method to tune and investigate hole quantum dots in Ge/Si nanowires, highlighting the anisotropic g-factor behavior not previously characterized in detail.

Findings

Demonstrated tunable single and double quantum dots in Ge/Si nanowires.

Observed a strongly anisotropic g-factor with |g_para| ≈ 0.60 and |g_perp| < 0.12.

Revealed magnetic field orientation dependence of the g-factor in hole quantum dots.

Abstract

We demonstrate fully tunable single and double quantum dots in a one-dimensional hole system based on undoped Ge/Si core-shell nanowire heterostructures. The local hole density along the nanowire is controlled by applying voltages to five top gate electrodes with a periodicity of 80 nm, insulated from the wire by a 20 nm-thick HfO_2 dielectric film. Low-temperature transport measurements were used to investigate the magnetic field dependence of Coulomb blockade peaks in a single quantum dot and indicate a strongly anisotropic g-factor with |g_para| = 0.60 +/- 0.03 and |g_perp| < 0.12.