Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 31: Quantum dots and wires: Optical properties III

HL 31.7: Talk

Wednesday, March 28, 2007, 16:30–16:45, H17

Spin dynamics of coupled nuclear-electron system over millitesla magnetic fields in n-doped quantum dots — •Thomas Auer¹, Sergey Verbin², Roman Cherbunin², Ruth Oulton³, Dmitri Yakovlev¹, Manfred Bayer¹, Dirk Reuter⁴, and Andreas Wieck⁴ — ¹Experimentelle Physik 2, Otto-Hahn-Strasse 4, 44227 Dortmund — ²V. A. Fock Institute, St. Petersburg State University, 198504 St. Petersburg, Russia — ³University of Sheffield, Hicks Building, Hounsfield Rd, S3 7RH, Sheffield, UK — ⁴Angewandte Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum

The hyperfine interaction between electrons and nuclei in quantum dots has a significant effect on the spin dynamics of both systems. The nuclear system may be polarized by optically pumping with spin polarized electrons, such that the often very large fields generated have a significant effect on the spin dynamics of the electron. In turn, the effective field from the electron (Knight field <1 mT) also strongly influences the spin dynamics of the polarized nuclei. By applying external magnetic fields of the same magnitude (few mT) one may access a rich variety of complex interactions between the two systems. We demonstrate that the Knight field, which is crucial in allowing nuclear polarization to occur at 0T, may be partially compensated by an external field. In addition, we demonstrate that the strongly-coupled electron-nuclear system, which in the absence of applied field forms a stable configuration with a sub-second spin lifetime, is strongly perturbed by the application of mT fields, with the lifetimes dramatically modified depending on field orientation.