Topological phase transition between composite-fermion and Pfaffian daughter states near {\nu} = 1/2 FQHS

TL;DR

This study reports the observation of a potential topological phase transition near filling factor 1/2 in GaAs quantum wells, indicating a transition from Jain states to Pfaffian daughter states, with implications for understanding non-Abelian quantum Hall states.

Contribution

The paper provides experimental evidence for a topological phase transition between composite-fermion and Pfaffian states near ν=1/2, supporting the existence of a non-Abelian Pfaffian state in wide quantum wells.

Findings

Observation of strong 1/2 FQHS with large energy gaps.

Sudden emergence of 8/17 and 7/13 FQHSs as the 1/2 FQHS strengthens.

Data suggest a transition from Jain states to Pfaffian daughter states.

Abstract

$\nu$=1/2 is among the most enigmatic many-body phases in two-dimensional electron systems as it appears in the ground-state rather than an excited Landau level. It is observed in wide quantum wells where the electrons have a bilayer charge distribution with finite tunneling. Whether this 1/2 FQHS is two-component (Abelian) or one-component (non-Abelian) has been debated since its experimental discovery over 30 years ago. Here, we report strong 1/2 FQHSs in ultrahigh-quality, wide, GaAs quantum wells, with transport energy gaps up to $\simeq$4K, among the largest gaps reported for any even-denominator FQHS. The 1/2 FQHS is flanked by numerous, Jain-sequence FQHSs at $\nu$=$p$/(2$p$$\pm$1) up to $\nu$=8/17 and 9/17. Remarkably, as we raise the density and strengthen the 1/2 FQHS, the 8/17 and 7/13 FQHSs suddenly become strong, much stronger than their neighboring high-order FQHSs. Insofar as FQHSs at $\nu$=8/17 and 7/13 are precisely the theoretically-predicted, simplest, daughter states of the one-component Pfaffian 1/2 FQHS, our data suggest a topological phase-transition of 8/17 and 7/13 FQHSs from the Jain-states to the daughter states of the Pfaffian, and that the parent 1/2 FQHS we observe is the Pfaffian state.