Periodic density modulation effects on a correlated two-dimensional composite fermion system

Abstract

We examine theoretically the effects caused by a periodic external potential on the correlated motion of a two-dimensional electron system under strong magnetic fields corresponding to a filling factor $\frac{1}{2}.$ To describe the resulting complex dynamics, we adopt a composite fermion approach and we determine in a two loop approximation the density-response function ${K}_{00}(\mathbf{q},\ensuremath{\omega})$ and the compressibility. We show explicitly that the long-wavelength limit of ${K}_{00}(\mathbf{q},\ensuremath{\omega})$ exhibits substantial anisotropic behavior induced by the modulation, and that the system tends to be incompressible in a direction orthogonal to the modulation as opposed to its response along the modulation.