Edge magnetoplasma excitations in quantum wire arrays

We report the low-temperature microwave properties of edge magneto-plasma excitations in quantum-wire arrays, fabricated from a two-dimensional electron gas in a GaAs/AlGaAs heterostructure and embedded in the slots of a 50-Ω meandering coplanar waveguide. The plot of frequency versus Landau level filling factors with strong absorption gives a series of barn-shaped curves with tops being centered in the quantum Hall effect plateaus and following a straight line through the origin. Away from the plateau center, the absorption dip becomes weaker and disappears near the plateau–plateau transition regime, qualitatively following the magneto hydrodynamic model. At frequencies above this barn-shaped part, however, we also observed unexpected resonant dips.