# Spin dynamics of quadrupole nuclei in InGaAs quantum dots

## TL;DR

This study investigates the spin dynamics of quadrupole nuclei in InGaAs quantum dots through photoluminescence polarization under varying magnetic fields and modulation frequencies, revealing distinct relaxation times for different nuclear spin states.

## Contribution

It introduces a phenomenological model that distinguishes the dynamics of nuclear fields associated with different nuclear spin states in quantum dots, highlighting the unique behavior of quadrupole nuclei.

## Key findings

- Nuclear field BNd relaxes in about 0.5 seconds.
- Nuclear field BNq relaxes approximately 1000 times faster.
- Hanle curves are significantly affected by modulation period variations.

## Abstract

Photoluminescence polarization is experimentally studied for samples with (In,Ga)As/GaAs selfassembled quantum dots in transverse magnetic field (Hanle effect) under slow modulation of the excitation light polarization from fractions of Hz to tens of kHz. The polarization reflects the evolution of strongly coupled electron-nuclear spin system in the quantum dots. Strong modification of the Hanle curves under variation of the modulation period is attributed to the peculiarities of the spin dynamics of quadrupole nuclei, which states are split due to deformation of the crystal lattice in the quantum dots. Analysis of the Hanle curves is fulfilled in the framework of a phenomenological model considering a separate dynamics of a nuclear field BNd determined by the +/- 12 nuclear spin states and of a nuclear field BNq determined by the split-off states +/- 3/2, +/- 5/2, etc. It is found that the characteristic relaxation time for the nuclear field BNd is of order of 0.5 s, while the relaxation of the field BNq is faster by three orders of magnitude.