Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 33: Spindynamics / Switching III
MA 33.8: Vortrag
Freitag, 30. März 2007, 12:45–13:00, H23
Ultrafast Spin Dynamics in GaMnN — •Nils Janßen1, Tim Thomay1, Markus Beyer1, Ulrich Rüdiger1, Mario Gjukic2, Tobias Graf2, Martin Brandt2, and Rudolf Bratschitsch1 — 1Fachbereich Physik und Centrum für Angewandte Photonik, Universität Konstanz, D-78457 Konstanz, Germany — 2Walter Schottky Institut, Technische Universität München, D-85784 Garching, Germany
We perform time-resolved Faraday rotation measurements on epitaxial GaN layers doped with Manganese in concentrations of the order of 1020 cm−3. Optical absorption and electron spin resonance studies indicate that the majority of Manganese is built into the GaN host crystal either as Mn3+ ions or as "Mn2+ + hole" complexes.
With circularly polarized ultraviolet pump pulses resonant to the fundamental bandgap, we excite spin-polarized electrons and holes. The spin of these carriers precesses in an externally applied transverse magnetic field. The time-dependent magnetization is detected via polarization rotation of a delayed probe pulse transmitted through the sample. By slightly tuning the excitation energy above the absorption edge, we are able to selectively address Mn states, most likely resulting in the formation of "Mn2+ + hole" complexes. These data show a strongly temperature dependent g-factor.