Suppression of nuclear spin diffusion at a GaAs/AlGaAs interface measured with a single quantum dot nano-probe

TL;DR

This study measures nuclear spin polarization dynamics in GaAs/AlGaAs quantum dots, revealing suppressed spin diffusion at the interface with decay times around a minute and a significantly reduced diffusion coefficient compared to bulk GaAs.

Contribution

It provides the first direct measurement of nuclear spin diffusion suppression at a GaAs/AlGaAs interface using a single quantum dot nano-probe.

Findings

Nuclear polarization decay time ~1 minute

Spin diffusion coefficient two orders lower than bulk GaAs

Inefficient nuclear spin diffusion at the interface

Abstract

Nuclear spin polarization dynamics are measured in optically pumped individual GaAs/AlGaAs interface quantum dots by detecting the time-dependence of the Overhauser shift in photoluminescence (PL) spectra. Long nuclear polarization decay times of ~ 1 minute have been found indicating inefficient nuclear spin diffusion from the GaAs dot into the surrounding AlGaAs matrix in externally applied magnetic field. A spin diffusion coefficient two orders lower than that previously found in bulk GaAs is deduced.