Fine Structure of Excitons and the Overhauser Effect in Quantum Dots

We present an experimental and theoretical study of the exciton-nuclear spin system in n-InP quantum dots. The polarised luminescence of an exciton bound to a neutral donor complex reveals anisotropic exchange splitting of optically active and inactive excitons. Optically oriented donor electrons and electrons in excitons polarise the lattice nuclei by hyperfine interaction. In turn, the polarised nuclei create an effective nuclear magnetic field affecting the polarisation of excitons. All nuclei species are polarised in InP islands, with the In nuclei undergoing a strong quadrupole interaction.