Freiburg 2019 – scientific programme
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FM: Fall Meeting
FM 63: Poster: Enabling Technologies: Quantum Materials, Quantum Dots, Quantum Wires, Point Contacts and Superconducting Systems
FM 63.1: Poster
Wednesday, September 25, 2019, 16:30–18:30, Tents
Light-driven nuclei thermodynamics in bulk GaAs and (In,Ga)As/GaAs quantum dots — •Pavel Sokolov1, Mikhail Petrov2, Kirill Kavokin2, Maria Kuznecova2, Sergey Verbin2, Dirk Reuter3, Andreas D. Wieck4, Dmitri Yakovlev1,5, and Manfred Bayer1,5 — 1Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund, Germany — 2Spin Optics Laboratory, Saint Petersburg State University, 198504 St. Petersburg, Russia — 3Department Physik Universität Paderborn, D-33098 Paderborn, Germany — 4Angewandte Festkörperphysik Ruhr-Universität Bochum, D-44780 Bochum, Germany — 5Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
We study experimentally the optical cooling dynamics of nuclei located inside the donor orbit in n-doped GaAs and (In,Ga)As/GaAs quantum dots and show that at slow modulation of excitation polarization (∼1 s) a noticeable Overhauser field can be observed. The initial cooling rate is strongly dependent on the direction of the external magnetic field with respect to initial electron polarization direction ± S0. The lowest spin temperature in n-GaAs, ΘN=1.5 mK was achieved in this work after cooling for Tmod=1 s. For the microstructure with (In,Ga)As/GaAs quantum dots, the achieved spin temperature is one order of magnitude lower than in n-GaAs: ΘN=0.1 mK. Using the implemented technique allows us to verify the polarization of nuclear spins in the external magnetic field in the desired spin polarization state in two different types of semiconductor microstructures studied in this work.