Electric-field switching of exciton spin splitting in coupled quantum dots

TL;DR

This paper theoretically demonstrates that electric fields can control exciton spin splitting in coupled quantum dots with magnetic ions, enabling on/off switching and inducing bright-to-dark exciton transitions affecting photoluminescence.

Contribution

It introduces a method to electrically switch exciton spin splitting in coupled quantum dots containing magnetic ions, highlighting the role of hole mixing and bonding-antibonding state transitions.

Findings

Spin splitting can be switched on/off by electric field via sp-d exchange.

Bright-to-dark exciton transition significantly influences photoluminescence.

Ground exciton state transitions are driven by hole mixing effects.

Abstract

We investigate theoretically the spin splitting of the exciton states in semiconductor coupled quantum dots (CQDs) containing a single magnetic ion. We find that the spin splitting can be switched on/off in the CQDs \textit{via} the \textit{sp-d}exchange interaction using the electric field. An interesting bright-to-dark exciton transition can be found and significantly affects the photoluminescence spectrum. This phenonmenon is induced by the transition of the ground exciton state, arising from the hole mixing effect, between the bonding and antibonding states.