Formation of a non-magnetic, odd-denominator fractional quantized conductance in a quasi-one-dimensional electron system

We have investigated the transport properties of a two-dimensional electron gas confined to one dimension by voltages applied to a pair of split gates and an additional top gate deposited on the surface of the GaAs/AlGaAs heterostructure. At low carrier concentrations, <5 × 1010 cm−2, in a wide 1D channel (700 nm), with an asymmetric confinement potential, the conductance plateaux in units of e2/h at 1 and 2/3 were observed. In the presence of a fixed in-plane magnetic field of 10 T, additional plateaux at 2/5 and 2/7 appeared with increasing asymmetry in confinement potential. The appearance of odd-denominator fractional states seems to originate from the zigzag formed when electrons are allowed to relax in the second dimension at the boundary of the 1D-2D transition.