Role of hyperfine interaction on electron spin optical orientation in charge‐controlled InAs–GaAs single quantum dots

We report on electron spin physics in a single charge‐tunable self‐assembled InAs/GaAs quantum dot. The hyperfine interaction between the optically oriented electron and nuclear spins leads to the polarization of the quantum dot nuclei. The sign of the resulting Overhauser‐shift depends on the trion state X + or X – , and remarkably its strength does not vanish in zero magnetic field. This explains the quenching of X + spin relaxation under steady‐state excitation polarization. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)