Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 52: Quantum dots and wires: Optical properties IV

HL 52.2: Talk

Friday, March 31, 2006, 11:15–11:30, POT 151

Co-dependence of electron and nuclear spin systems and ultra-long spin lifetimes in self-assembled QDs — •Ruth Oulton¹, A. Greilich¹, S. Verbin^1,2, R.V Cherbunin^1,2, I.V. Ignatiev^1,2, D.R. Yakovlev¹, M. Bayer¹, I. Merkulov³, V. Stavarache⁴, D. Reuter⁴, and A. Wieck⁴ — ¹Experimentelle Physik II, Universität Dortmund, 44221 Dortmund, Germany — ²Institute of Physics, St.Petersburg State University, St.Petersburg, Russia — ³A.F. Ioffe Physico-Technical Institute, RAS, St.Petersburg, 194021, Russia — ⁴Angewandte Festkörperphysik, Ruhr-Universität Bochum, Germany

The hyperfine interaction between electrons and randomly orientated nuclei in QDs is predicted to lead to fast electron spin decoherence over a timescale of nanoseconds. An aligned nuclear and electron spin system, however, is predicted to be ultra-stable, with spin lifetimes much larger than that of either the electron or the nuclei in isolation. We demonstrate an accumulation of PL polarization and subsequent preservation of spin memory in n-doped QDs over a millisecond timescale, indicative of a strong co-dependence of the resident electron and nuclear spins. Application of small (10 -100microT) external fields demonstrate that the weak effective electronic magnetic field on the nuclei is the key to achieving and maintaining the co-aligned system.