Spin dynamics in electrochemically charged CdSe quantum dots

TL;DR

This study investigates how electrochemical charging affects spin dynamics in colloidal CdSe quantum dots using time-resolved Faraday rotation, revealing changes in g-factors, coherence times, and surface state influences at room temperature.

Contribution

It demonstrates the impact of electrochemical charging on spin properties and coherence in CdSe quantum dots, highlighting the role of surface states and charging levels.

Findings

Disappearance of one Lande g-factor upon filling of the 1Se electron level

Increase in transverse spin coherence time with charging voltage

Spin precession amplitude peaks near half-filling potential

Abstract

We use time-resolved Faraday rotation to measure coherent spin dynamics in colloidal CdSe quantum dots charged in an electrochemical cell at room temperature. Filling of the 1Se electron level is demonstrated by the bleaching of the 1Se-1S3/2 absorption peak. One of the two Lande g-factors observed in uncharged quantum dots disappears upon filling of the 1Se electron state. The transverse spin coherence time, which is over 1 ns and is limited by inhomogeneous dephasing, also appears to increase with charging voltage. The amplitude of the spin precession signal peaks near the half-filling potential. Its evolution at charging potentials without any observable bleaching of the 1Se-1S3/2 transition suggests that the spin dynamics are influenced by low-energy surface states.