Spin-phonon coupling in single Mn doped CdTe quantum dot

TL;DR

This paper theoretically investigates the mechanisms of Mn spin relaxation in a laser-driven CdTe quantum dot, highlighting the role of phonon interactions and exciton effects in enabling optical Mn spin polarization.

Contribution

It introduces a comprehensive model of Mn spin dynamics considering phonon coupling, exciton interactions, and optical pumping in single Mn-doped CdTe quantum dots.

Findings

Mn-phonon coupling is enhanced by excitons.

Phonon-induced hole spin relaxation contributes to Mn spin relaxation.

The model successfully explains optically induced Mn spin pumping.

Abstract

The spin dynamics of a single Mn atom in a laser driven CdTe quantum dot is addressed theoretically. Recent experimental results\cite{Le-Gall_PRL_2009,Goryca_PRL_2009,Le-Gall_PRB_2010}show that it is possible to induce Mn spin polarization by means of circularly polarized optical pumping. Pumping is made possible by the faster Mn spin relaxation in the presence of the exciton. Here we discuss different Mn spin relaxation mechanisms. First, Mn-phonon coupling, which is enhanced in the presence of the exciton. Second, phonon-induced hole spin relaxation combined with carrier-Mn spin flip coupling and photon emission results in Mn spin relaxation. We model the Mn spin dynamics under the influence of a pumping laser that injects excitons into the dot, taking into account exciton-Mn exchange and phonon induced spin relaxation of both Mn and holes. Our simulations account for the optically induced Mn spin pumping.