Repulsion of fundamental edge magnetoplasmons at integer filling factors and nonlocal responses

A microscopic treatment of edge magnetoplasmons (EMPs) is presented for strong magnetic fields, low temperatures, integer filling factors ν, and confining potentials that allow Landau-level (LL) flattening to be neglected. Local and nonlocal contributions to the current density are included. The effect of nonlocality on the fundamental EMPs is weak while other modes can be substantially affected. For $\nu=1,2$ nonlocal responses result in a dipole mode with dispersion relation $\omega\sim q_x^3$. For $\nu=4, 6$, inter-LL Coulomb coupling leads to a strong repulsion of the uncoupled, fundamental LL modes