Terahertz photoresponse of quantum wires in magnetic fields

We have investigated the terahertz photoresponse of quantum wires in high magnetic fields, employing intense far-infrared (FIR) radiation from the UCSB Free-Electron Lasers. Both GaAs-based and InAs-based quantum wires, with widths ranging from 50 nm to 1 μm, were studied. At high FIR power we observed Shubnikov-de Haas type oscillations in photoresponse versus magnetic field, B, resulting from non-resonant electronic heating; the oscillations were much more pronounced than those in resistance versus B. At low FIR power we observed resonant peaks due to magnetoplasmon excitations, whose strength shows strong polarization-dependence and whose energy extrapolates to a finite value at zero B. These results provide a powerful tool for characterizing ID electronic states in quantum wires.