Spin conversion rates due to dipolar interactions in mono-isotopic quantum dots at vanishing spin-orbit coupling

TL;DR

This paper investigates how dipolar interactions influence electron spin decay in mono-isotopic quantum dots at very low spin-orbit coupling, highlighting the effects of symmetry and temperature on decay rates.

Contribution

It introduces a symmetry-based method to identify spin decay channels and analyzes the impact of phonon-induced transitions on temperature-dependent spin decay.

Findings

Spin decay channels depend on electron number and quantum dot symmetry.

Rapid increase in spin decay rate occurs at low temperatures due to phonon effects.

Symmetry considerations can suppress certain spin decay pathways.

Abstract

Dipolar interaction between the magnetic moments of electrons is studied as a source for electron spin decay in quantum dots or arrays of quantum dots. This magnetic interaction will govern spin decay, after other sources, such as the coupling to nuclear spins or spin orbit coupling, have been eliminated by a suitable sample design. Electron-electron (Coulomb) interactions, important for magnetic properties, are included. Decomposing the dipolar operator according to the symmetric group of electron permutations allows one to deduce vanishing decay channels as a function of electron number and spatial symmetries of the quantum dot(s). Moreover, we incorporate the possibility of rapid phonon induced spin conserving transitions which crucially affect the temperature dependence of spin decay rates. An interesting result is that a sharp increase of the spin decay rate occurs already at relatively low temperatures.