Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 21: III-V semiconductors II

HL 21.6: Talk

Tuesday, March 27, 2007, 12:15–12:30, H17

Spin Noise Spectroscopy in GaAs — •Michael Römer, Jens Hübner, and Michael Oestreich — Institute for Solid State Physics, Gottfried Wilhelm Leibniz University of Hannover, Appelstr. 2, 30167 Hannover

We successfully employ spin noise spectroscopy in semiconductor materials as a new sensitive tool to measure the spin-coherence time of electrons and the electron Landé g–factor in n-GaAs nearly interaction free [1]. Our technique avoids common problems like carrier heating and electron spin relaxation due to spin interaction with optically created holes.

Spin noise spectroscopy in semiconductors empowers us to measure extremely long spin coherence times in excess of 200 ns at low temperatures, which may have been masked in the past by effects like those mentioned above.

We furthermore discuss the measured noise power and spin-coherence time in dependence of the probe energy position, sample temperature and doping concentration. The results compare very well with a theory based on Poisson distribution probability.

The spin noise spectrum is measured by below band-gap Faraday-rotation in n-doped GaAs at low temperatures with high frequency spectrum analysis techniques.

[1] M. Oestreich, M. Römer, R. Haug, and D. Hägele, “Spin Noise Spectroscopy in GaAs”, Phys. Rev. Lett. 95, 216603 (2005).