Spin dynamics of an individual Cr atom in a semiconductor quantum dot under optical excitation

TL;DR

This study investigates the spin dynamics of a single Cr atom in a quantum dot using photon correlation, revealing spin fluctuation timescales around 10 ns and insights into spin relaxation mechanisms.

Contribution

It provides the first detailed analysis of individual Cr atom spin dynamics in quantum dots under optical excitation, highlighting exciton-Cr interactions.

Findings

Spin fluctuations occur on a 10 ns timescale.

Transfer time between Cr spin states is quantitatively measured.

Intrinsic Cr spin relaxation time is at least 20 ns.

Abstract

We studied the spin dynamics of a Cr atom incorporated in a II-VI semiconductor quantum dot using photon correlation techniques. We used recently developed singly Cr-doped CdTe/ZnTe quantum dots (A. Lafuente-Sampietro {\it et al.}, [1]) to access the spin of an individual magnetic atom. Auto-correlation of the photons emitted by the quantum dot under continuous wave optical excitation reveals fluctuations of the localized spin with a timescale in the 10 ns range. Cross-correlation gives quantitative transfer time between Cr spin states. A calculation of the time dependence of the spin levels population in Cr-doped quantum dots shows that the observed spin dynamics is controlled by the exciton-Cr interaction. These measurements also provide a lower bound in the 20 ns range for the intrinsic Cr spin relaxation time.