Even-Denominator Fractional Quantum Hall State at Filling Factor {\nu} = 3/4

TL;DR

This paper reports the discovery of a new even-denominator fractional quantum Hall state at filling factor 3/4 in a high-quality 2D hole system, suggesting potential non-Abelian properties in the lowest Landau level.

Contribution

It presents the first observation of an even-denominator FQHS at 3/4 in a 2D hole system within the lowest Landau level, expanding understanding of fractional quantum Hall states.

Findings

Strong resistance minimum at ν=3/4

Hall plateau observed at (h/e2)/(3/4)

Likely a non-Abelian state from composite fermion interactions

Abstract

Fractional quantum Hall states (FQHSs) exemplify exotic phases of low-disorder two-dimensional (2D) electron systems when electron-electron interaction dominates over the thermal and kinetic energies. Particularly intriguing among the FQHSs are those observed at even-denominator Landau level filling factors, as their quasi-particles are generally believed to obey non-Abelian statistics and be of potential use in topological quantum computing. Such states, however, are very rare and fragile, and are typically observed in the excited Landau level of 2D electron systems with the lowest amount of disorder. Here we report the observation of a new and unexpected even-denominator FQHS at filling factor {\nu} = 3/4 in a GaAs 2D hole system with an exceptionally high quality (mobility). Our magneto-transport measurements reveal a strong minimum in the longitudinal resistance at {\nu} = 3/4, accompanied by a developing Hall plateau centered at (h/e2)/(3/4). This even-denominator FQHS is very unusual as it is observed in the lowest Landau level and in a 2D hole system. While its origin is unclear, it is likely a non-Abelian state, emerging from the residual interaction between composite fermions.