Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 48: Focus Session: Spintronics (jointly with MA)

HL 48.7: Talk

Wednesday, March 28, 2012, 11:45–12:00, EW 201

Time-resolved electrical detection of optically triggered spin coherence in InGaAs — •Ivan Stepanov¹, Stefan Göbbels¹, Tobias Wenz¹, Gernot Güntherodt¹, Mihail Lepsa², and Bernd Beschoten¹ — ¹II. Physikalisches Institut, RWTH Aachen University, Germany — ²Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich GmbH, Germany

Direct conversion of electron spin precession into a detectable electrical voltage plays an important role in many spintronic concepts. In previous experiments spin-dependent photocurrents were observed in DC measurements on 2DEGs and QWs and could be explained by the spin-galvanic effect (SGE) [1].

Here we report on the first time-resolved electrical measurement of the spin-dependent photo-voltage in n-InGaAs. Phase triggering of electron spin coherence is achieved by circularly polarized picosecond laser pulses. Electron spin precession in a transverse external magnetic field can be directly monitored as photo-voltage oscillations using a phase-triggered sampling oscilloscope as a probe. The magnetic field dependence of phase and amplitude of the photo-voltage along [110] agree well with the predictions of the SGE. Time-resolved Faraday rotation (TRFR) measurements on the same sample under identical experimental conditions show good agreement between the measured spin dephasing times and the g-factor in the photo-voltage probes and the TRFR.

This Work has been supported by DFG through FOR 912

[1] S.D. Ganichev et al., Nature 417, p. 153 (2002)