Influence of metastable states of two-dimensional electrons on the electronic properties of composite fermions

Sweeping the magnetic field at low temperatures can result in metastable states of the system of two-dimensional electrons in GaAs/${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As. These nonequilibrium states are stable in the range of filling factors 1/3<ν<1, but can be changed by an extremely small variation of magnetic field around ν≳1, which is accompanied by a drastic change in magnetoresistivity. We used this phenomenon to vary the disorder and to study its influence on the electronic properties of two-dimensional electrons in the regime of the fractional quantum Hall effect and, especially, in the vicinity of ν=1/2.