Particle-hole Asymmetry of Fractional Quantum Hall States in the Second Landau Level of a Two-dimensional Hole System

TL;DR

This study reports the first observation of a fractional quantum Hall state at filling factor 8/3 in a two-dimensional hole system, revealing particle-hole asymmetry likely caused by Landau level mixing.

Contribution

It provides the first unambiguous detection of the 8/3 fractional quantum Hall state in a hole system and highlights the asymmetry with the 7/3 state due to Landau level mixing.

Findings

Observation of the 8/3 state with a 40 mK energy gap.

The 7/3 state does not develop down to 6.9 mK, contrary to electron systems.

Evidence suggests Landau level mixing causes particle-hole asymmetry.

Abstract

We report the first unambiguous observation of a fractional quantum Hall state in the Landau level of a two-dimensional hole sample at the filling factor $\nu=8/3$. We identified this state by a quantized Hall resistance and an activated temperature dependence of the longitudinal resistance and found an energy gap of 40 mK. To our surprise the particle-hole conjugate state at filling factor $\nu=7/3$ in our sample does not develop down to 6.9 mK. This observation is contrary to that in electron samples in which the 7/3 state is typically more stable than the 8/3 state. We present evidence that the asymmetry between the 7/3 and 8/3 states in our hole sample is due to Landau level mixing.