COLLECTIVE EDGE EXCITATIONS IN THE QUANTUM HALL REGIME - EDGE HELICONS AND LANDAU-LEVELS

Based on a microscopic evaluation of the local current density, a trea tment of edge magnetoplasmons is presented for confining potentials th at allow Landau level (LL) flattening to be neglected. Mode damping du e to electron-phonon interaction is evaluated. For v = 1,2 there exist independent modes that are either spatially symmetric or antisymmetri c with respect to the edge. Certain modes that change shape during pro pagation are nearly undamped even for very strong dissipation and are termed ''edge helicons.'' For v > 2 inter-LL Coulomb coupling leads to a strong repulsion of the decoupled LL fundamental modes. The theory agrees well with recent experiments.