Thermoelectric response of fractional quantized Hall and re-entrant insulating states in the N=1 Landau level

TL;DR

This study measures the thermopower of 2D electrons in the N=1 Landau level, revealing fractional quantum Hall states and re-entrant insulators, and discusses implications for non-abelian quasiparticles.

Contribution

It provides detailed thermopower measurements at fractional quantum Hall states, including at $ u=5/2$, and links thermoelectric behavior to non-abelian quasiparticle theories.

Findings

Observation of fractional quantized Hall states at $ u=5/2$ and 7/3

Abrupt thermopower collapse below 40 mK at re-entrant insulators

Thermopower behavior consistent with non-abelian quasiparticle theories

Abstract

Detailed measurements of the longitudinal thermopower of two-dimensional electrons in the first excited Landau level are reported. Clear signatures of numerous fractional quantized Hall states, including those at $\nu = 5/2$ and 7/3, are observed in the magnetic field and temperature dependence of the thermopower. An abrupt collapse of the thermopower is observed below about $T= 40$ mK at those filling factors where re-entrant insulating electronic states have been observed in conventional resistive transport studies. The thermopower observed at $\nu = 5/2$ is discussed in the context of recent theories which incorporate non-abelian quasiparticle exchange statistics.