Magnetoplasmons at boundaries between two-dimensional electron systems

Magnetoplasmons localized at the boundary between two classical two-dimensional electron systems with different electron densities are observed and described in detail for the first time. In high magnetic fields the frequency of these interedge magnetoplasmons is proportional to the difference in electron density, dn, on either side of the boundary and inversely proportional to the magnetic field. The direction of propagation is determined by the sign of dn. A coupling between interedge modes and conventional edge modes at small spatial separation is observed