Untersuchungen zu komplexen 3D Grenzschichtablösungen an einem Höhenleitwerksmodell
Final Report Abstract
In the present project we have investigated the full frequency and momentum dependence of the density response matrix function of the two-dimensional electron gas with spin-orbit (SO) coupling. Its components describe a response of the system to external charge and spin density perturbations (local electric and magnetic fields). Due to the momentum dependence of the spin-orbit coupling there emerge new specific features in the system's properties. We have established how the transitions between SO-split subbands affect the polarizability of the system and the properties of the collective charge density oscillations. We have also observed that in the similar way the SO coupling can affect the lifetime of the longitudinal optical phonon. We have investigated the spin-density response to the external charges as well as the reciprocal effect. Both of them become possible in the presence of the SO coupling. The existence of nonvanishing spin-charge off-diagonal term in the matrix response function leads to a formation of nontrivial mixtures of the collective charge and spin density modes. The latter can be visible in the spectral properties of the renormalized susceptibilities. In particular, due to the spin-charge mixing it becomes possible to observe by means of inelastic Raman scattering the sharp plasmon-like peak in the in-plane magnetization, which has no analogies in the absence of spin-orbit coupling. This is a result of the nontrivial interplay of the SO coupling and the exchange interaction. We have established the correct expressions for the charge and spin susceptibilies in the static limit. On their basis we have considered the modifications of the Kohn anomaly and spatial behavior of the effective potential as well as of the RKKY interaction due to the SO coupling. We have also studied the role of impurities and described the crossover from the diffusive to the ballistic regimes in the system's response in the presence of the SO coupling. We have observed a possibility for propagating density modes with spin-resolved dispersions for the case of the SO splitting larger than a disorder broadening. The calculated response functions can serve as a basis for subsequent studies of correlation effects in the two-dimensional electron gas with the SO coupling. The SO-induced damping of the collective modes (plasmons, magnons, phonons) as well as the SO-induced features in the lineshapes of the charge and spin susceptiblities can be verified experimentally.
Publications
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C.J. Kahler, R. Hain, M. Kruse, P. Scholz: Investigation of separation bubbles at low and high Reynolds number with Time-Resolved and Long-Distance Micro-PIV, European Windtunnel Association (EWA), International workshop on advanced measurement techniques in aerodynamics, Rome, 31. March - 02. April 2008
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Kruse, M. Radespiel. R.: " Measurement of a Laminar Separation Bubble on a Swept Horizontal Tailplane using JJPIV", 38th Fluid Dynamics Conference and Exhibit. Seattle, Washington, 23 - 26 June 2008, AIAA 2008-4054
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Kruse, M., Radespiel, R.:, "Windkanaluntersuchung einer laminaren Ablöseblase in Nasenbereich eines Profils mit Hilfe von //PIV bei Re = 660000 ". 15. GALAFachtagung, Rostock, 04-06. Sept. 2007,
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Kruse, M., Radespiel. R., "Fernmikroskopische//-PIV Untersuchungen einer laminaren Ablöseblase am Höhenleitwerie eines Windkanalmodells", 13. DGLR Stab Workshop. Göttingen, Germany, 11. Oct. 2007.
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Kruse, M., Wokoeck, R.. Hain. R.: "Windkanaluntersuchung einer laminaren Ablöseblase in Nasenbereich eines Profils mit Hilfe von //PIV bei Re = 660000", In: Proceedings der 15. GALA-Fachtagung "Lasenmethoden in der Strömungsmesstechnik", 4. - 6. September 2007, Universität Rostock, Hrsg.: Leder, A., Brede, M., Hüttmann, F., Ruck, B., Dopheide. D., ISBN 978-3-86009-007-7
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Probst, A., "Enweiterungen zur statistischen Turt^ulenzmodellierung im DLR TAU Code", DGLR . Braunschweig. Gemiany, 2006. DGLR 2006-230, DGLR Jahrtjuch 2006 Bd. 1
