Dynamic nuclear polarization of a single charge-tunable InAs ∕ GaAs quantum dot

• Published in: Physical review. B, Condensed matter and materials physics Vol. 74; no. 8
• Main Authors: Eble, B., Krebs, O., Lemaître, A., Kowalik, K., Kudelski, A., Voisin, P., Urbaszek, B., Marie, X., Amand, T.
• Format: Journal Article
• Language: English
• Published: American Physical Society 01-08-2006
• Subjects: Condensed Matter; Other; Physics; quantum dot; optical orientation; Nuclear polarization; trion
• ISSN: 1098-0121; 1550-235X
• DOI: 10.1103/PhysRevB.74.081306

We report on the dynamic nuclear polarization of a single charge-tunable self-assembled InAs/GaAs quantum dot in a longitudinal magnetic field of $\sim$0.2T. The hyperfine interaction between the optically oriented electron and nuclei spins leads to the polarization of the quantum dot nuclei measured by the Overhauser-shift of the singly-charged excitons ($X^{+}$ and $X^{-}$). When going from $X^{+}$ to $X^{-}$, we observe a reversal of this shift which reflects the average electron spin optically written down in the quantum dot either in the $X^{+}$ state or in the final state of $X^{-}$ recombination. We discuss a theoretical model which indicates an efficient depolarization mechanism for the nuclei limiting their polarization to ~10%.