Effect of external magnetic field on electron spin dephasing induced by hyperfine interaction in quantum dots

TL;DR

This paper studies how an external magnetic field affects electron spin dephasing in quantum dots caused by hyperfine interactions, revealing that magnetic fields can suppress spin polarization loss.

Contribution

It provides a detailed analysis of magnetic field effects on hyperfine-induced spin dephasing, highlighting the potential to control spin coherence in quantum dots.

Findings

Dephasing rate is linked to nuclear field dispersion.

External magnetic field can suppress spin polarization loss.

Hyperfine interaction does not fully depolarize electron spins.

Abstract

We investigate the influence of an external magnetic field on spin phase relaxation of single electrons in semiconductor quantum dots induced by the hyperfine interaction. The basic decay mechanism is attributed to the dispersion of local effective nuclear fields over the ensemble of quantum dots. The characteristics of electron spin dephasing is analyzed by taking an average over the nuclear spin distribution. We find that the dephasing rate can be estimated as a spin precession frequency caused primarily by the mean value of the local nuclear magnetic field. Furthermore, it is shown that the hyperfine interaction does not fully depolarize electron spin. The loss of initial spin polarization during the dephasing process depends strongly on the external magnetic field, leading to the possibility of effective suppression of this mechanism.