Manifestation of the magnetic depopulation of one-dimensional subbands in the optical absorption of acoustic magnetoplasmons in side-gated quantum wires

We have investigated experimentally and theoretically the far-infrared (FIR) absorption of gated, deep-mesa-etched GaAs/Al$_x$Ga$_{1-x}$As quantum wires. To overcome Kohn's theorem we have in particular prepared double-layered wires and studied the acoustic magnetoplasmon branch. We find oscillations in the magnetic-field dispersion of the acoustic plasmon which are traced back to the self-consistently screened density profile in its dependence on the magnetic depopulation of the one-dimensional subbands.