Counter-propagating Fractional Hall states in mirror-symmetric Dirac semi-metals

TL;DR

This paper predicts a new class of counter-propagating fractional quantum Hall states in mirror-symmetric Dirac semi-metals, characterized by a Laughlin-like wavefunction and robust conductance at fractional filling factors.

Contribution

It introduces a novel fractional Hall state in Dirac semi-metals with mirror symmetry, including a specific wavefunction and conductance properties, expanding the understanding of topological states.

Findings

Proposes a Laughlin-like wavefunction at charge neutrality.

Shows the conductance $\sigma_{xx} = 2e^2/(m h)$ is robust.

Identifies counter-propagating fractional Hall states at $| u_{\pm}|=1/m$.

Abstract

The Landau bands of mirror symmetric 2D Dirac semi-metals (for example odd-layers of ABA-graphene) can be identified by their parity with respect to mirror symmetry. This symmetry facilitates a new class of counter-propagating Hall states at opposite but equal electron and hole filling factors $|\nu_{\pm}|=1/m$ ({\it m} odd). Here, we propose a Laughlin-like correlated liquid wavefunction, at the charge neutrality point, that exhibits fractionally charged quasi-particle/hole pair excitation of opposite parity. Using a bosonized one-dimensional edge state theory, we show that the longitudinal conductance of this state, $\sigma_{xx} = 2e^2/(m h)$, is robust to short-ranged inter-mode interactions.