Anisotropic plasmon dispersion in a lateral quantum-wire superlattice

Plasmon excitations for a lateral superlattice of quantum wires in a modulation-doped GaAs/(AlGa)As multiple-quantum-well system have been investigated by resonant inelastic light scattering. The Raman spectra exhibit a set of resonances with a strongly anisotropic dispersion. For momentum transfer parallel to the wires, a significant dispersion is observed; perpendicular to the wires, the dispersion is nearly flat. This is an experimental proof that Coulomb interaction between neighboring wires is weak and that the excitations represent confined plasmons of the individual wires. They provide a direct measure of the width of the electron channels.