Competition Between Fractional Quantum Hall Liquid, Bubble and Wigner Crystal Phases in the Third Landau Level

TL;DR

This study investigates the competition between different quantum phases in the third Landau level of a high-mobility GaAs/AlGaAs quantum well, revealing new fractional quantum Hall states and a quantum phase transition between bubble and Wigner crystal phases.

Contribution

It provides experimental evidence of a fractional quantum Hall liquid forming in the N=2 Landau level and identifies a magnetically driven phase transition between bubble and Wigner crystal phases.

Findings

Discovery of new minima in magnetoresistance at specific filling factors.

Evidence for a fractional quantum Hall liquid in the N=2 Landau level.

Observation of a quantum phase transition between bubble and Wigner crystal phases.

Abstract

Magnetotransport measurements were performed in a ultra-high mobility GaAs/AlGaAs quantum well of density $\sim 3.0 \times 10^{11}$ $cm^{-2}$. The temperature dependence of the magnetoresistance $R_{xx}$ was studied in detail in the vicinity of $\nu={9/2}$. In particular, we discovered new minima in $R_{xx}$ at filling factor $\nu\simeq 4{1/5}$ and $4{4/5}$, but only at intermediate temperatures $80\lesssim T\lesssim 120$ mK. We interpret these as evidence for a fractional quantum Hall liquid forming in the N=2 Landau level and competing with bubble and Wigner crystal phases favored at lower temperatures. Our data suggest that a magnetically driven insulator-insulator quantum phase transition occurs between the bubble and Wigner crystal phases at T=0.