Collective Edge Excitations In The Quantum Hall Regime: Edge Helicons And Landau-level Structure

Based on a microscopic evaluation of the local current density, a treatment of edge magnetoplasmons (EMP) is presented for confining potentials that allow Landau level (LL) flattening to be neglected. Mode damping due to electron-phonon interaction is evaluated. For nu=1, 2 there exist independent modes spatially symmetric or antisymmetric with respect to the edge. Certain modes, changing shape during propagation, are nearly undamped even for very strong dissipation and are termed edge helicons. For nu > 2 inter-LL Coulomb coupling leads to a strong repulsion of the decoupled LL fundamental modes. The theory agrees well with recent experiments.