Single Dirac-Cone State and Quantum Hall Effects in Honeycomb Structure

TL;DR

This paper introduces the single Dirac-cone state in honeycomb lattices, analyzing its quantum Hall effects and topological properties, revealing potential for large spin-Chern numbers in magnetic fields.

Contribution

It proposes a novel single Dirac-cone state in honeycomb structures and explores its quantum Hall effects and topological characteristics, expanding understanding of topological phases.

Findings

Unconventional quantum Hall effects linked to the single Dirac-cone state.

Potential for arbitrarily large spin-Chern numbers in magnetic fields.

Identification of physical systems where this state can be realized.

Abstract

A honeycomb lattice system has four types of Dirac electrons corresponding to the spin and valley degrees of freedom. We consider a state that contains only one type of massless electrons and three types of massive ones, which we call the single Dirac-cone state. We analyze quantum Hall (QH) effects in this state. We make a detailed investigation of the Chern and spin-Chern numbers. We make clear the origin of unconventional QH effects discovered in graphene. We also show that the single Dirac-cone state may have arbitrary large spin-Chern numbers in magnetic field. Such a state will be generated in antiferromagnetic transition-metal oxides under electric field or silicene with antiferromagnetic order under electric field.