Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 25: Spin controlled transport I
HL 25.5: Vortrag
Dienstag, 26. Februar 2008, 15:15–15:30, EW 202
Micro coils for spin manipulation in semiconductors — •Chen Yuansen1, Simon Halm1, Tilmar Kümmell1, Gerd Bacher1, Tomasz Wojtowicz2, Grzegorz Karczewski2, and Wiater Maciej2 — 1Werkstoffe der Elektrotechnik,Universtät Duisburg-Essen, BismarckStr.81,47057,Duisburg,Germany — 2Institute of Physics, Polish Academy of Science, Al.Lotnikow 32/46 02-668 Warsasw, Poland
In the research field of spintronics, local spin manipulation in semiconductors is one of the main goals. We used micro-structured aluminum coils to generate a switchable magnetic field in a CdMnTe/CdMgTe diluted magnetic semiconductor (DMS) quantum well (QW). As the effective g factor in a DMS QW is large (~200 at 4K), carrier spin states can efficiently be manipulated even with low magnetic fields. Inside the coil area a magnetic field of several 10mT is obtained which allows to partly align the Mn2+ ions spins, and, via the sp-d exchange interaction, to polarize the spins of optically generated excitons. We investigated the spin polarization inside the micro coils by means of micro-photoluminescence spectroscopy. Without the need of an external magnetic field, we observed a spin polarization of up to +/-1.5% at 4K by introducing a positive or negative current, respectively. By applying current pulses, the spin polarization could be switched and measured with 100 ns time resolution. The current induced spin polarization is observed up to 40K. It was found that heat produced by the current disorders the Mn2+ spins and thus competes with the ordering achieved by the current-induced magnetic field.