Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 63: III-V Semiconductors
HL 63.10: Vortrag
Freitag, 26. März 2010, 12:45–13:00, H13
GHz Spin Noise Spectroscopy in n-Doped Bulk GaAs — •Georg Müller, Michael Römer, Jens Hübner, and Michael Oestreich — Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstr. 2, 30167 Hannover, Germany
We advance spin noise spectroscopy (SNS) to GHz frequencies in order to resolve high frequency spin dynamics in n-doped bulk GaAs [1]. SNS relies on the statistical imbalance of electron spins in thermodynamical equilibrium, which is detected by below band gap Faraday rotation. Hence, SNS is an ideal experimental tool to deliver intrinsic spin lifetimes. In the past, these advantages could not be exploited to full extend since the bandwidth of the detection system (≲ 1 GHz) has capped SNS to slow spin dynamics at relatively low frequencies. In the advanced experimental method of GHz SNS, ps laser pulses are utilized as probe light. The spin dynamics in the sample at the Larmor frequency is sampled by the repetition rate of the laser such that spin noise at frequencies above 10 GHz can be detected without any loss of sensitivity. With this new measurement technique at hand, we study the magnetic field dependence up to 3 T of the electron Landé-g-factor g∗ and the spin dephasing time T2∗ of two n-doped bulk GaAs samples at and above the metal-to-insulator transition (MIT). Our findings reveal in conjecture with high aperture SNS, which allows depth resolved SNS measurements, that the observed inhomogeneous broadening of the spin dephasing rate at the MIT originates from a local g-factor variation in the sample due to surface electron depletion.
[1] G. M. Müller et al., arXiv:0909.3406 (2009).