Chong Long CAO's Thesis Defense : "Modelling of the spin dynamics of an individual magnetic atom in a quantum dot"

Friday 13 January 2012 at 2pm

Room D420 - Institut Néel -Building D

CNRS Polygone scientifique

25 rue des martyrs, 38000 Grenoble

Chong Long CAO (Institut Néel)  

Thesis supervisor: Lucien BESOMBES & Joaquin FERNANDEZ-ROSSIER

We have studied the spin dynamics of an individual Mn atom embedded a CdTe quantum dot. Our results show that the Mn spin relaxation is faster when the quantum dot contains an exciton. This can result in an optical orientation of the Mn spin. The valence band mixing is the critical parameter for the fast relaxation rates of the Mn spin in the exchange field of the exciton. This valence band mixing is controlled by the shape and strain of the quantum dot. The influence of these parameters on the optical pumping dynamics were analyzed in detail. Our simulation of optical pumping are in good agreement with experiments. The coherent dynamics of an individual Mn spin was also investigated. We discussed the influence of the coherent dynamics of the coupled electronic and nuclear spins on the optical pumping. We have shown that optically controlled coupling between electronic and nuclear spins could be used for Mn spin switching. We finally demonstrated that the combination of resonant laser and microwave fields can be used to optically detect the magnetic resonance of a Mn spin in a CdTe quantum dot.