Atomistic theory of spin relaxation in self-assembled In$_{1-x}$Ga$_x$As/GaAs quantum dots at zero magnetic field

TL;DR

This paper provides atomistic calculations of spin relaxation times for electrons and holes in self-assembled InGaAs/GaAs quantum dots at zero magnetic field, highlighting the dominant two-phonon process for holes.

Contribution

It introduces a detailed atomistic model for spin relaxation in quantum dots, emphasizing the role of two-phonon processes at zero magnetic field.

Findings

Electron spin relaxation time: 40-80 seconds at 4.2 K

Hole spin relaxation time: 1-20 milliseconds at 4.2 K

Hole relaxation times agree with recent experiments

Abstract

We present full atomistic calculations of the spin-flip time (T$_{1}$) of electrons and holes mediated by acoustic phonons in self-assembled In$_{1-x}$Ga$_x$As/GaAs quantum dots at zero magnetic field. At low magnetic field, the first-order process is suppressed, and the second-order process becomes dominant. We find that the spin-phonon-interaction induced spin relaxation time is 40 - 80 s for electrons, and 1 - 20 ms for holes at 4.2 K. The calculated hole-spin relaxation times are in good agreement with recent experiments, which suggests that the two-phonon process is the main relaxation mechanism for hole-spin relaxation in the self-assembled quantum dots at zero field. We further clarify the structural and alloy composition effects on the spin relaxation in the quantum dots.