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HL: Fachverband Halbleiterphysik

HL 4: Spintronics: Nanostructures and Optics

HL 4.1: Vortrag

Montag, 7. März 2016, 09:30–09:45, H13

Nuclear spin polarization in the electron spin-flip Raman scattering of singly charged (In,Ga)As/GaAs quantum dots — •Philipp Waldkirch¹, J. Debus¹, D. Kudlacik¹, V. F. Sapega², D. Dunker¹, P. Bohn¹, F. Paßmann¹, D. Braukmann¹, J. Rautert¹, D. R. Yakovlev^1,2, D. Reuter³, A. D. Wieck⁴, and M. Bayer^1,2 — ¹Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany — ²Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia — ³Department Physik, Universität Paderborn, 33098 Paderborn, Germany — ⁴Angewandte Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany

We show that resonant, two-color spin-flip Raman scattering (SFRS) cannot only be used to manipulate carrier spins in a singly charged ensemble of (In,Ga)As QDs [1], but can also sensitively indicate the coupling of carrier spins to the surrounding nuclear spin bath, i.e., to study the central spin problem [2]. This method allows for monitoring the dynamic nuclear spin polarization directly through the Overhauser shift of the electron-SFRS line, while its width is determined by nuclear spin fluctuations. The rapid temporal decay of the Overhauser shift with slightly increasing temperature is caused by phonon-induced electron spin-flips that depolarize the nuclear spin system. The mechanism of the two-color SFRS is discussed together with the electron-nuclear hyperfine interaction and Pauli exclusion principle.

[1] J. Debus et al., Phys. Rev. B 90, 235404 (2014)

[2] J. Debus et al., Phys. Rev. B 92, 195421 (2015)