Specific heat and entropy of fractional quantum Hall states in the second Landau level

TL;DR

This study measures the specific heat of fractional quantum Hall states in the second Landau level, revealing activated behavior and entropy consistent with prior thermopower data, and suggests potential for detecting non-Abelian quasiparticle entropy.

Contribution

It introduces a novel method to measure the specific heat of fractional quantum Hall states via electron-phonon thermalization, overcoming background challenges.

Findings

Activated behavior of specific heat at 5/2 and 7/3 states

Entropy measurements align with thermopower data

Technique may detect non-Abelian quasiparticle entropy

Abstract

Specific heat has had an important role in the study of superfluidity and superconductivity, and could provide important information about the fractional quantum Hall effect as well. However, traditional measurements of the specific heat of a two-dimensional electron gas are difficult due to the large background contribution of the phonon bath, even at very low temperatures. Here, we report measurements of the specific heat per electron in the second Landau level by measuring the thermalization time between the electrons and phonons. We observe activated behaviour of the specific heat of the 5/2 and 7/3 fractional quantum Hall states, and extract the entropy by integrating over temperature. Our results are in excellent agreement with previous measurements of the entropy via longitudinal thermopower. Extending the technique to lower temperatures could lead to detection of the non-Abelian entropy predicted for bulk quasiparticles at 5/2 filling