Possible Fractional Quantum Hall Effect in Graphite

TL;DR

This study reports the observation of fractional quantum Hall effect signatures in highly oriented pyrolytic graphite under high magnetic fields, indicating complex electron interactions and phase transitions in this material.

Contribution

It provides experimental evidence of fractional quantum Hall effect signatures in graphite, a material not traditionally associated with this phenomenon.

Findings

Sign change in Hall resistivity indicating electron to hole transition

Enhanced basal plane resistivity suggesting charge density wave or Wigner crystallization

Detection of Hall plateaus consistent with fractional quantum Hall effect

Abstract

Measurements of basal plane longitudinal rho_b(B) and Hall rho_H(B) resistivities were performed on highly oriented pyrolytic graphite (HOPG) samples in pulsed magnetic field up to B = 50 T applied perpendicular to graphene planes, and temperatures 1.5 K < T < 4.2 K. At B > 30 T and for all studied samples, we observed a sign change in rho_H(B) from electron- to hole-like. For our best quality sample, the measurements revealed the enhancement in rho_b(B) for B > 34 T (T = 1.8 K), presumably associated with the field-driven charge density wave or Wigner crystallization transition. Besides, well defined plateaus in rho_H(B) were detected in the ultra-quantum limit revealing the signatures of fractional quantum Hall effect in graphite.