Fermi Liquid to Luttinger Liquid Transition at the Edge of a Two-Dimensional Electron Gas

We present experimental results on the tunneling into the edge of a two-dimensional electron gas (2DEG) obtained with a GaAs/AlGaAs cleaved edge overgrown structure. While the 2DEG exhibits typical fractional quantum Hall features of a very high mobility sample, we observe the onset of a nonlinear current-voltage characteristic in the vicinity of ν0ex0ex=0ex0ex1. For filling factor ν<1 the system is consistent with a non-Fermi liquid behavior, such as a Luttinger liquid, whereas for ν>1 we observe an Ohmic tunneling resistance between the edge and a three-dimensional contact, typical for a Fermi liquid. Finally, we show that the Luttinger liquid exponent at a given filling factor is not universal but depends on sample parameters.