Berlin 2018 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 33: Poster Session III
HL 33.20: Poster
Mittwoch, 14. März 2018, 17:30–19:30, Poster F
Subsecond nuclear spin dynamics in n-doped GaAs — •Pavel Sokolov1,2, Mikhail Petrov2, Kirill Kavokin2,3, Maria Kuznetsova2, Sergey Verbin2, Dmitri Yakovlev1,3, and Manfred Bayer1,3 — 1Experimentelle Physik 2, TU Dortmund, Dortmund, Germany — 2Spin Optics Laboratory, Saint Petersburg State University, St. Petersburg, Russia — 3Ioffe Physical Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia
In this work, we report experimental studies of the Nuclear Spin (NS) relaxation in presence of optical excitation in n-doped GaAs (nd=4 · 1015). The time-resolved photoluminescence study allows us to address a fast subsecond NS dynamics. The NS relaxation time, TS, is extracted by the time-of-flight method commonly used for investigation the kinetics of the photoluminescence decays. Extrapolation of the subsecond spin relaxation times a weak power of excitation allows us to conclude on the existence of the fast NS relaxation dynamics, which has not been studied so far. We show, that the process is governed by the dynamic polarization of NSs subject to an external magnetic field a time-dependent Knight field of photo-generated electrons encourage also the warm-up of NS bath and relaxation of the non-equilibrium NS. We find that the spin relaxation time TS is observed in a subsecond time range showing a decrease of TS from 75 ms down to 40 ms with the pumping power varied by an order of magnitude. The experimental results are interpreted within the developed model predicting a drop of the NS polarization when the light helicity modulation rate reaches a characteristic value determined by ratio 1/ √T1 T2.