Helical Edge Transport in the \nu = 0 Quantum Hall Ferromagnetic State of an Organic Dirac Fermion System

TL;DR

This study experimentally confirms the presence of helical edge states in the u=0 quantum Hall ferromagnetic state of an organic Dirac fermion system, demonstrating edge transport properties distinct from bulk effects.

Contribution

It provides the first experimental evidence of helical edge transport in a layered organic Dirac system's quantum Hall ferromagnetic state.

Findings

Saturation of interlayer magnetoresistance occurs when magnetic field is along the side surface.

Angle dependence of magnetoresistance is absent in Corbino geometry.

Results rule out chiral magnetic effect as the cause of observed phenomena.

Abstract

We experimentally confirm the \nu = 0 quantum Hall ferromagnetic (QHF) state, accompanied by helical edge states, in the layered organic Dirac-fermion system \alpha-(ET)2I3 by demonstrating helical edge transport in multilayers. The saturation of interlayer magnetoresistance (MR) in the high-magnetic-field quantum limit does not scale with the sample cross-sectional area and appears when the magnetic field is oriented along the side surface. The in-plane MR exhibits a similar angle dependence, whereas this feature disappears in the Corbino geometry where no edge channels are present. These results are consistent with helical edge transport in the multilayer QHF state. They also rule out the possibility that the observed angle-dependent MR arises from the chiral magnetic effect expected for a 3D Dirac or Weyl semimetal.