Anomalies of the fractional quantum hall effect in a wide ballistic wire

Magnetotransport in a ballistic wire under the conditions of integer and fractional quantization was studied experimentally. A nonlinear magnetic-field dependence of filling factor (ν) of the Landau level was observed; this dependence arises if the self-consistent electrostatic potential of the wire has a specific form. It is assumed that the observed effect results from the influence of interaction between electrons at the partially occupied Landau level on this potential, which brings about a decrease in the electron concentration in the wire as the magnetic field increases in the case of ν<1.