AC measurements of the minimum longitudinal resistance of a QHE sample from 10 Hz to 10 kHz

AC measurements of the longitudinal resistance, R/sub xx/, of a quantum Hall effect (QHE) sample have been made in a frequency range from 10 Hz to 10 kHz. The results show no frequency effect on the minimum value of R/sub xx/ corresponding to the quantum numbers i=2 and i=4, within the measurement resolution of 0.5 m/spl Omega/. Therefore, the influence of frequency on the value of the quantized Hall resistance, R/sub H/, should not exceed a few parts in 10/sup 9/. Some unwanted effects detected during the development of the resistance bridge have been pointed out.