Plasmons and magnetoplasmons in partially bounded two-layer electron systems

We have analytically studied plasmons in an electron system comprised of two spatially separated layers -- an infinite two-dimensional electron system (2DES) and a 2D strip. Our analysis reveals the existence of plasmon modes that are localized near and propagate along the strip. These modes are characterized by the wave vector in the direction of the strip, as well as the number of charge density nodes, N, across the strip. In the long-wavelength limit, the fundamental mode N=0 is found to have gapless linear dispersion. When the external perpendicular magnetic field is applied, this mode remains gapless and exhibits peculiar magnetodispersion. We analyze the correlation between our findings and the previously established results on plasmons in gated and partially gated 2DESs.