Microscopic Origin of the Next-Generation Fractional Quantum Hall Effect

Most of the fractions observed to date belong to the sequences ν=n/(2pn±1) and ν=1-n/(2pn±1), n and p integers, understood as the familiar integral quantum Hall effect of composite fermions. These sequences fail to accommodate, however, many fractions such as ν=4/11 and 5/13, discovered recently in ultrahigh mobility samples at very low temperatures. We show that these “next generation” fractional quantum Hall states are accurately described as the fractional quantum Hall effect of composite fermions.