Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 26: III-V semiconductors I
HL 26.6: Vortrag
Dienstag, 26. Februar 2008, 17:00–17:15, EW 202
Current pulse induced coherence of spin packets injected across a Fe/GaAs interface — •C. Schwark1,5, J. Moritz1,5, L. Schreiber1,5, B. Beschoten1,5, G. Güntherodt1,5, M. Lepsa2,5, C. Adelmann3, C. Palmstrøm3, and P. Crowell4 — 1II. Physikalisches Institut, RWTH Aachen, Templergraben 55, 52056 Aachen — 2Institut für Bio- und Nanosysteme IBN-1, Forschungszentrum Jülich, 52425 Jülich — 3Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA — 4School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA — 5Virtuelles Institut für Spinelektronik (VISel), Aachen-Jülich-Göttingen
Efficient electrical spin injection from a ferromagnet into a semiconductor has been demonstrated for various material systems by steady-state experiments. We introduce a novel time-resolved technique based on electrical pumping and optical probing. As a pump we apply ultrafast current pulses (≥ 200ps) to electrically inject spin packets from an iron layer through a reverse biased Schottky barrier into a 5 µm thick n-GaAs layer, which exhibits spin dephasing times exceeding 50 ns at 20 K. Probing the electrically injected spin packets by time-resolved Faraday rotation using a pulsed probe laser beam, we observe up to 10 lamor precessions and resonant spin amplification [1] in a transverse magnetic field. This evidences that the current pulses trigger the phase coherence of the electrically injected spin packets.
Work supported by BMBF, DFG, and HGF.
[1] J. M. Kikkawa et al., Phys. Rev. Lett. 80 (1998)