Signatures of spin in the n=1/3 Fractional Quantum Hall Effect

TL;DR

This paper investigates how the activation gap at filling factor 1/3 in the fractional quantum Hall effect varies with magnetic field, revealing a transition from spin texture excitations to Coulomb-like behavior.

Contribution

It provides the first detailed measurement of the activation gap across a wide magnetic field range at fixed filling factor 1/3, highlighting a crossover in excitation types.

Findings

Activation gap shows a linear dependence on B at low fields.

At high fields, the gap exhibits Coulomb-like behavior.

The study offers insights into mobility edges in the fractional quantum Hall regime.

Abstract

The activation gap Delta of the fractional quantum Hall state at constant filling n =1/3 is measured in wide range of perpendicular magnetic field B. Despite the full spin polarization of the incompressible ground state, we observe a sharp crossover between a low-field linear dependence of Delta on B associated to spin texture excitations and a Coulomb-like behavior at large B. From the global gap-reduction we get information about the mobility edges in the fractional quantum Hall regime.