The charge density relaxation propagator of a two dimensional electron system, which is the slope of the imaginary part of the polarization function, exhibits singularities for bosonic momenta having the order of the spin-orbit momentum and depending
on the momentum orientation. We have provided an intuitive understanding for this non-analytic behavior in terms of the inter chirality subband electronic transitions, induced by the combined action of Bychkov-Rashba (BR) and Dresselhaus (D) spin-orbit coupling. It is shown that the regular behavior of the relaxation propagator is recovered in the presence of only one BR or D spin-orbit field or for spin-orbit interaction with equal BR and D coupling strengths. This creates a new possibility to influence carrier relaxation properties by means of an applied electric field.
By exploiting our recently derived exact formula for the Lindhard polarization function in the presence of Bychkov-Rashba (BR) and Dresselhaus (D) spin-orbit interaction (SOI), we show that the interplay of different SOI mechanisms induces highly ani
sotropic modifications of the static dielectric function. We find that under certain circumstances the polarization function exhibits doubly-singular behavior, which leads to an intriguing novel phenomenon, beating of Friedel oscillations. This effect is a general feature of systems with BR+D SOI and should be observed in structures with a sufficiently strong SOI.
Spin-orbit coupling induced anisotropies of plasmon dynamics are investigated in two-dimensional semiconductor structures. The interplay of the linear Bychkov-Rashba and Dresselhaus spin-orbit interactions drastically affects the plasmon spectrum: th
e dynamical structure factor exhibits variations over several decades, prohibiting plasmon propagation in specific directions. While this plasmon filtering makes the presence of spin-orbit coupling in plasmon dynamics observable, it also offers a control tool for plasmonic devices. Remarkably, if the strengths of the two interactions are equal, not only the anisotropy, but all the traces of the linear spin-orbit coupling in the collective response disappear.
We study the spin Coulomb drag in a quasi-two-dimensional electron gas beyond the random phase approximation (RPA). We find that the finite transverse width of the electron gas causes a significant reduction of the spin Coulomb drag. This reduction,
however, is largely compensated by the enhancement coming from the inclusion of many-body local field effects beyond the RPA, thereby restoring good agreement with the experimental observations by C. P. Weber textit{et al.}, Nature, textbf{437}, 1330 (2005).
