On the nature of tunable hole g-factors in quantum dots

TL;DR

This paper demonstrates a giant, electrically tunable hole g-factor in SiGe nanocrystals, revealing a novel orbital effect mechanism that modulates the g-factor through electric field-induced wave function displacement.

Contribution

It introduces a new mechanism for g-factor control in quantum dots based on orbital effects and wave function displacement, previously overlooked in literature.

Findings

Giant modulation of hole g-factor observed under electric field.

Orbital effect of magnetic field influences g-factor via wave function mixing.

Non-monotonic g-factor behavior linked to wave function displacement.

Abstract

Electrically tunable g-factors in quantum dots are highly desirable for applications in quantum computing and spintronics. We report giant modulation of the hole g-factor in a SiGe nanocrystal when an electric field is applied to the nanocrystal along its growth direction. We derive a contribution to the g-factor that stems from an orbital effect of the magnetic field, which lifts the Kramers degeneracy in the nanocrystal by altering the mixing between the heavy and the light holes. We show that the relative displacement between the heavy- and light-hole wave functions, occurring upon application of the electric field, has an effect on the mixing strength and leads to a strong non-monotonic modulation of the g-factor. Despite intensive studies of the g-factor since the late 50's, this mechanism of g-factor control has been largely overlooked in the literature.