Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 19: Symposium Spin Effects in Semiconductors of Reduced Dimensionality

HL 19.2: Hauptvortrag

Dienstag, 26. Februar 2008, 11:00–11:30, ER 270

Local spin manipulation in a semiconductor by nanostructured ferromagnets — Patric Hohage, Simon Halm, Jörg Nannen, and •Gerd Bacher — Werkstoffe der Elektrotechnik, Universität Duisburg-Essen, Duisburg, Germany

The ability to locally define and manipulate carrier spin states in a semiconductor is one key issue in spintronics. We use fringe fields provided by tiny ferromagnets with well-defined magnetization to obtain local spin control in an underlying semiconductor.

In a first series of experiments, the fringe field of microstructured Fe/Tb multilayer ferromagnets with out-of-plane magnetization was used to imprint a remanent magnetization into the magnetic ion system of a magnetic semiconductor. This results in a locally varying carrier spin polarization of up to 25 % at zero external fields. We show that the ferromagnetic state can be switched by an intense laser pulse and probe the magneto-optical response of the semiconductor. In a second series of experiments fringe fields stemming from ferromagnets with in-plane magnetization are used to locally modify the coherent spin dynamics of both, electrons and magnetic ions. We demonstrate the ability of a complete reversal of the spin orientation within the spin coherence time of magnetic ions in CdMnZnSe quantum wells with respect to a reference measurement and discuss the potential of locally manipulating coherent spin states in GaAs up to room temperature.

*work done in collaboration with Y. Fan, J. Puls, F. Henneberger (HU Berlin), E. Schuster, W. Keune (U Duisburg-Essen), D. Reuter, A. Wieck, S. Fischer, U. Kunze (U Bochum)