Electric-field dependent g-factor anisotropy in Ge-Si core-shell nanowire quantum dots

TL;DR

This study investigates how the effective g-factor in Ge-Si core-shell nanowire quantum dots varies with magnetic field orientation, revealing anisotropic behavior linked to spin-orbit interactions, which could enable electric control of spin qubits.

Contribution

The paper provides experimental evidence of angle-dependent g-factor anisotropy in Ge-Si nanowire quantum dots, confirming theoretical predictions about Rashba-type spin-orbit effects.

Findings

g* is maximized when magnetic field is perpendicular to nanowire and electric field

g* is significantly reduced when magnetic field aligns with electric field

g* is nearly quenched when magnetic field aligns with nanowire axis

Abstract

We present angle-dependent measurements of the effective g-factor g* in a Ge-Si core-shell nanowire quantum dot. g* is found to be maximum when the magnetic field is pointing perpendicular to both the nanowire and the electric field induced by local gates. Alignment of the magnetic field with the electric field reduces g* significantly. g* is almost completely quenched when the magnetic field is aligned with the nanowire axis. These findings confirm recent calculations, where the obtained anisotropy is attributed to a Rashba-type spin-orbit interaction induced by heavy-hole light-hole mixing. In principle, this facilitates manipulation of spin-orbit qubits by means of a continuous high-frequency electric field.