Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 31: Quantum dots and wires: Optical properties III

HL 31.5: Talk

Wednesday, March 28, 2007, 15:45–16:00, H17

Reliable parallel electrical initialization of spin-polarized electrons in InGaAs/GaAs quantum dots — W. Löffler, C. Mauser, J. Lupaca-Schomber, S. Li, T. Passow, H. Reimer, C. Klingshirn, M. Hetterich, and •H. Kalt — Institut für Angewandte Physik and DFG Center for Functional Nanostructures (CFN), Universität Karlsruhe (TH), 76128 Karlsruhe, Germany

We show that electron spins can be initialized electrically with near 100% fidelity in InGaAs/GaAs quantum dots. This is done by injecting spin-polarized electrons from a semimagnetic spin-aligner layer (ZnMnSe) into the quantum dots. At a moderate external magnetic field (3-6 Tesla), we observe only emission from one of the Zeeman doublet states in the quantum dot. That means the initialization error is below our experimental resolution of about one percent. This result is surprising as the polarization of quantum dot ensembles is far below unity. To reveal the origin of this discrepancy, statistical analysis of the electron spin in many different quantum dots has been done.