Charge-density response function of two-dimensional electron systems in a magnetic field

Abstract

We examine charge density excitations in two-dimensional electron systems in a strong perpendicular magnetic field. Our theoretical framework is the extended random-phase approximation (extended RPA, ERPA), which takes into account all the second-order self-energies of particle-hole propagators. Our results are different from the RPA response functions qualitatively, and are consistent with recent empirical findings. We explain our results in detail in connection with two-particle-two-hole degrees of freedom and the Kohn theorem.