We study the static dielectric function $\varepsilon \mathrm{}\left(q\right)\mathrm{}$ of two-dimensional electron system with spin-orbit coupling in the frame of the random-phase approximation. We demonstrate that, in addition to the well-known ${2k}_F$-Kohn anomaly, spin-orbit coupling gives rise to the novel anomaly in the dielectric function at small ${q=q}_0\ll k_F,$ where $q_0$ is the distance between two Fermi surfaces. As a result of this anomaly a large-distance behavior of the potential from a point charge exhibits (in addition to the conventional Friedel oscillations) oscillations with a period $2\pi {/q}_0.$ The remarkable feature of these oscillations is that they are not smeared out by the temperature. We show that the small-$q$ anomaly also modifies the indirect exchange interaction of localized magnetic moments (RKKY interaction). In the presense of spin-orbit coupling this interaction acquires a high-temperature component.

• Received 29 September 1998

DOI:https://doi.org/10.1103/PhysRevB.59.5090