Highly Non-linear Excitonic Zeeman Spin-Splitting in Composition-Engineered Artificial Atoms

TL;DR

This paper reports the observation and explanation of highly non-linear Zeeman splitting in engineered quantum dots, highlighting how composition and size influence magnetic properties for potential quantum applications.

Contribution

It provides a microscopic explanation for non-linear Zeeman splitting in quantum dots using eight-band k.p simulations based on realistic structural parameters.

Findings

Non-linear Zeeman splitting observed in InGaAs quantum dots.

Quadratic Zeeman energy contribution from heavy-light hole mixing.

Large lateral size and dilute In composition enhance non-linearities.

Abstract

Non-linear Zeeman splitting of neutral excitons is observed in composition engineered In(x)Ga(1-x)As self-assembled quantum dots and its microscopic origin is explained. Eight-band k.p simulations, performed using realistic dot parameters extracted from cross-sectional scanning tunneling microscopy, reveal that a quadratic contribution to the Zeeman energy originates from a spin dependent mixing of heavy and light hole orbital states in the dot. The dilute In-composition (x<0.35) and large lateral size (40-50 nm) of the quantum dots investigated is shown to strongly enhance the non-linear excitonic Zeeman gap, providing a blueprint to enhance such magnetic non-linearities via growth engineering.