Energy Gap and Spin Polarization in the 5/2 Fractional Quantum Hall Effect

TL;DR

This paper investigates the nature of the 5/2 fractional quantum Hall effect, focusing on its spin polarization and the effects of parallel magnetic fields, combining experimental data and theoretical analysis.

Contribution

It proposes that the 5/2 FQHE state may not be fully spin-polarized and analyzes how parallel fields influence its stability through disorder and Zeeman effects.

Findings

The 5/2 FQHE state might be partially spin-polarized.

Parallel magnetic fields primarily disrupt the 5/2 FQHE via disorder enhancement.

Zeeman energy significantly affects the FQHE stability.

Abstract

We consider the issue of the appropriate underlying wavefunction describing the enigmatic 5/2 fractional quantum Hall effect (FQHE), the only even denominator FQHE unambiguously observed in a single layer two dimensional (2D) electron system. Using experimental transport data and theoretical analysis, we argue that the possibility of the experimental 5/2 FQH state being not fully spin-polarized cannot be ruled out. We also establish that the parallel field-induced destruction of the 5/2 FQHE arises primarily from the enhancement of effective disorder by the parallel field with the Zeeman energy playing an important quantitative role.