We have studied the far-infrared response of GaAs/AlxGa1-xAs quantum-wire arrays of 200- and 300-nm periods, realized by biasing a periodic surface-grating gate structure below the two-dimensional electron-gas conduction threshold. We find that in our samples, which have substantially smaller periods than those in previous work, the resonance is observed at a frequency ωr much smaller than that of the depolarization-shifted subband resonance and that the 200-nm-period wires have a smaller ωr than the 300-nm-period wires of the same carrier densities. The experiment demonstrates mode softening in coupled quantum wires. We also present a theoretical model, based on the generalized Kohn theorem, to take into account the mode softening. Our model can quantitatively describe the observed mode softening and explain the experimental results.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics