Light-hole exciton mixing and dynamics in Mn-doped quantum dots

TL;DR

This paper theoretically studies how a single Mn atom in CdTe quantum dots influences light-hole exciton and biexciton spectra and dynamics through exchange interactions, revealing exchange-induced exciton mixing and Rabi oscillations.

Contribution

It introduces a detailed theoretical model combining Kohn-Luttinger theory and density matrix approach to analyze exchange effects in Mn-doped quantum dots, highlighting position-dependent exciton mixing.

Findings

Exchange-induced exciton mixing depends on Mn position.

Bright and dark light-hole excitons exhibit Rabi oscillations.

Biexcitons show damped Rabi oscillations due to relaxation processes.

Abstract

We investigate theoretically the spectral and dynamical effects of the short-range exchange interaction between a single manganese (Mn) atom hosted by cylindrical CdTe quantum dots and its light-hole excitons or biexcitons. Our approach is based on the Kohn-Luttinger KP theory and configuration interaction method, the dynamics of the system in the presence of intraband relaxation being derived from the von Neumann-Lindblad equation. The complex structure of the light-hole exciton absorption spectrum reveals the exchange-induced exciton mixing and depends strongly on the Mn position. In particular, if the Mn atom is closer to the edges of the cylinder the bright and dark light-hole excitons are mixed by the hole-Mn exchange alone. Consequently, their populations exhibit exchange-induced Rabi oscillations which can be viewed as optical signatures of light-hole spin reversal. Similar results are obtained for mixed biexcitons, in this case the exchange-induced Rabi oscillations being damped by the intraband hole relaxation processes. The effect of light-hole heavy-hole mixing is also discussed.