Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 10: Spinelectronics/Spininjection in Heterostructures
MA 10.5: Vortrag
Montag, 26. März 2007, 16:15–16:30, H23
Ultrafast spin and magnetization dynamics in diluted magnetic semiconductors — •Klaus Schmalbuch1, Johannes Bongers1, Bernd Beschoten1, Gernot Güntherodt1, Nicoleta Kaluza2, Hilde Hardtdegen2, Thomas Schäpers2, Mariana Ungureanu3, and Heidemarie Schmidt3 — 1II. Physikalisches Institut, RWTH Aachen and Virtuelles Institut für Spinelektronik VISel, Templergraben 55, 52056 Aachen — 2Institut für Bio- und Nanosysteme IBN-1, Forschungszentrum Jülich, 52425 Jülich — 3Institut für Experimentelle Physik II, Universität Leipzig, Linnéstraße 5, 04103 Leipzig
GaN and ZnO are promising material systems for applications in spinelectronics, since they provide extended electron spin coherence times because of their weak spin-orbit coupling. Furthermore these materials might become room temperature ferromagnets upon magnetic doping. To explore the influence of magnetic dopants on the ultrafast spin and magnetization dynamics in these semiconductors, we performed optical fs-pump-probe measurements on Cr-doped GaN and Gd-doped ZnO samples.
The results for the magnetically doped samples are qualitatively different in both systems: electron spin coherence in GaN is not affected by doping Cr at low concentrations. In ZnO:Gd dephasing times of conduction electrons are reduced compared to undoped ZnO. In addition we observe high frequency coherence at ps time scales which arises from the coherent sp-d exchange interaction between the local Gd moments and the conduction electrons. Work supported by HGF