Observation of a Fractional Quantum Hall State at $\nu=1/4$ in a Wide GaAs Quantum Well

TL;DR

This study reports the first observation of a fractional quantum Hall state at filling factor 1/4 in a wide GaAs quantum well, revealing new quantum phenomena in high magnetic fields at very low temperatures.

Contribution

The paper presents the experimental discovery of an even-denominator fractional quantum Hall state at ν=1/4 in a 50 nm wide GaAs quantum well, a novel observation in this material system.

Findings

FQH state at ν=1/4 observed at high magnetic fields

Clear Hall resistance plateau at ν=1/4 upon tilting the sample

Strong minimum in diagonal resistance indicating FQH state

Abstract

We report the observation of an even-denominator fractional quantum Hall (FQH) state at $\nu=1/4$ in a high quality, wide GaAs quantum well. The sample has a quantum well width of 50 nm and an electron density of $n_e=2.55\times10^{11}$ cm$^{-2}$. We have performed transport measurements at $T\sim35$ mK in magnetic fields up to 45 T. When the sample is perpendicular to the applied magnetic field, the diagonal resistance displays a kink at $\nu=1/4$. Upon tilting the sample to an angle of $\theta=20.3^o$ a clear FQH state at emerges at $\nu=1/4$ with a plateau in the Hall resistance and a strong minimum in the diagonal resistance.