Fractional Quantum Hall Effect at ν=1⁄7

Abstract

Magnetotransport experiments on a high mobility GaAs/AlGaAs heterostructure in magnetic fields up to 27 T and at temperatures down to 20 mK were performed. A structure in ρ_xy which shows the existence of the quantum liquid state at the filling factor ν=1⁄7 in a magnetic field up to 18 T was observed. However, the structure of ρ_xy with ν=1⁄7 at a magnetic field of 25 T was not observed. The possibility of the growth of the charge density wave and the coexistence of the quantum liquid state and CDW state due to the potential fluctuations are discussed in this paper.