Optically Induced Nuclear Spin Polarization in the Quantum Hall Regime: The Effect of Electron Spin Polarization through Exciton and Trion Excitations (1412.5941v3)

Abstract: We study nuclear spin polarization in the quantum Hall regime through the optically pumped electron spin polarization in the lowest Landau level. The nuclear spin polarization is measured as a nuclear magnetic field $B_N$ by means of the sensitive resistive detection. We find the dependence of $B_N$ on filling factor unmonotonous. The comprehensive measurements of $B_N$ with the help of the circularly polarized photoluminescence measurements indicate the participation of the photo-excited complexes i.e., the exciton and trion (charged exciton), in nuclear spin polarization. On the basis of a novel estimation method of the equilibrium electron spin polarization, we analyze the experimental data and conclude that the filling factor dependence of $B_N$ is understood by the effect of electron spin polarization through excitons and trions.