Dispersive and localized one-dimensional plasmons in very narrow quantum wires

We report on the Raman scattering determination of the dispersion of electronic excitations of 1D electron gases in deep etched GaAs wires, based on high mobility modulation-doped single-quantum wells. From the observation of well-defined 1D plasmons and of uncorrelated electron–hole pair excitations (or spin density waves, depending on the intepretation scheme), we deduce the electron density and lateral confining potential. We demonstrate the fabrication of high-quality 1D systems in the quantum limit, where a single 1D subband is occupied. We quantitatively analyse the measured dispersions and we discuss the possible roles of exchange-correlation corrections and of image charge effects. We critically discuss the interpretation of our results in terms of the Fermi versus Tomonoga–Lüttinger liquid descriptions.