Nuclear spin effects in negatively charged InP quantum dots

Effects of both the dynamic nuclear polarization (DNP) created by circularly polarized light and the fluctuations of average nuclear spin in a quantum dot (QD) on the electron spin orientation are studied for singly negatively charged InP QDs. From the dependence of the negative circular polarization of photoluminescence on the applied longitudinal magnetic field, the hyperfine field B_N of a few mT appearing due to DNP and the effective magnetic field B_f of a few tens of mT arising from nuclear spin fluctuations (NSF) are estimated. A lifetime of about 1 microsecond is estimated for NSF.