Fractional Quantization of the Hall Effect

Magnetotransport of two-dimensional electrons and holes was studied in magnetic fields up to 300 kG and temperatures down to 0. 5 K. In addition to previously reported structures at Landau-level filling factors =13 and 23, new structures were resolved at =43, 53, 25, 35, 45, and 27. The results suggest that fractional quantization of the Hall effect exists in multiple series, each based on the inverse of an odd integer.