We measure the Hall conductivity, σxy, on a Corbino geometry sample
of a high-mobility AlGaAs/GaAs heterostructure in a pulsed magnetic field. At a
bath temperature about 80 mK, we observe well expressed plateaux in
σxy at integer filling factors. In the pulsed magnetic field, the
Laughlin condition of the phase coherence of the electron wave functions is
strongly violated and, hence, is not crucial for σxy quantization.Comment: 4 pages, 4 figures, submitted to PR