Enigmatic 2+6/13 Filling Factor: A Prototype Intermittent Topological State

Abstract

Observation of filling factor 6/13 is one of the surprising fractional quantum Hall states in the second Landau level because, in contrast to the standard wisdom, the fractions ($\hat{I}½<1/2$) with lower numerators, namely 4 and 5, have not yet been observed. We find that a state indeed forms at $\hat{I}½=6/13$ as an intermittent topological state between two prominent states at $\hat{I}½=1/2$ and $\hat{I}½=2/5$ with lower numerators. Also, we predict that a state forms at $\hat{I}½=5/13$ as an intermittent to $\hat{I}½=2/5$ and $\hat{I}½=3/8$. Our proposed wave functions for $\hat{I}½=6/13$ and $5/13$ have excellent overlaps with the corresponding exact ground state wave functions. The Chern-Simons coupling matrices deduced from the form of these wave functions are analyzed to predict the topological properties, which may be experimentally verified.